This post covers concrete finishes that can be used in a healthy home.
Low and zero-VOC stains, dyes, and sealants can be used to provide color and sealing on concrete floors.
Many of these can be used on brick, concrete walls, and concrete countertops as well.
For those with chemical sensitivities, concrete floors can be a great non-toxic flooring option. To provide protection from stains or to create a more decorative look there are many finishes that are safe options.
This article contains affiliate links, upon purchase I earn a commission at no extra cost to you.
Polished Concrete Floors
Types of Polished Concrete
Grind & Seal
The first type of traditional polished concrete is “grind and seal”. In this method, the concrete is mechanically polished and then finished with a topical sealer whether it’s water-based, poly, or epoxy. The sealer provides the gloss/sheen.
This type of polished concrete is less expensive. The sealers can hide defects in the concrete.
Diamond Grind
Diamond Grind relies mostly on mechanical polishing. All of the sheen comes from the polishing – from matte to gloss sheen.
A penetrating densifier (also known as liquid glass – sodium, potassium, and lithium silicate) is used. The densifiers are very benign and safe products. (If you have ever used Radon Seal that is a liquid glass).
The concrete is very durable and difficult to scratch. Some companies also offer a topic sealer on top of that. But the least toxic option is certainly diamond grind with a densifier.
It is more susceptible to staining. This may not work on an existing slab, but it could.
You can change the color of the concrete by adding the oxides (pigments) discussed more in their own section below, to the concrete mix. You can also alter the color with the type of sand and aggregate used. You can get darker colors, browns, or whites.
Finishes for Polished Concrete
Cream polish (burnished) – the surface is polished but no stone is exposed.
Partial stone exposure (is also called hit and miss or salt and pepper) – This takes 1-3 mm off the top and shows some variation in the aggregate.
Full stone exposure – You can see the aggregate. This can take off 5-10 mm.
(You can see what they look like here)
Types of Coatings for Grind and Seal
Surface Coating
Types of surface coatings include epoxy, polyurethane, acrylic, and silanes.
Silanes are silicones and are usually solvent-based (and too harsh for those avoiding toxins).
Solvent-based sealers may not be breathable. Some water-based sealers that are acrylic-based are partially breathable.
Acrylic and polyurethane can both be quite tolerable for the chemically sensitive. I list more brands that are acrylic and polyurethane-based in the section on stains.
Epoxies are a two-part system that is certainly difficult to tolerate when wet. In an ideal world, the two parts perfectly combine and chemically react. The product will eventually cure and become safe.
If you are sensitive to chemicals, have a sample piece made up so that you know how long it takes to cure fully.
Many can be labeled zero-VOC. I’m not a fan of epoxy because of this initial harsh offgassing. It also normally needs maintenance every 2-5 years.
Brands for the chemically sensitive:
- Vocomp 25 is an acrylic sealer recommended by Paula Baker Laporte.
- Earth Paint NanoTech Floor Stain/Sealer – works on concrete as well as wood. This is an acrylic and polyurethane sealer. No silicones. The VOCs are listed at 95.86 g/l. I tested this product in my post on wood floor sealers.
- ECOS Solid Concrete Sealer and Semi-Transparent Concrete Sealer – These are acrylic coatings/stains. Though they do contain a PFAS (Perfluorylalkyl Ethanol).
- BioShield Aqua Resin Floor Finish – (I tested this very low-odor finish on wood floors.)
- AFM MexeSeal can be used on brick floors, certain tiles, and concrete.
Partial Penetrating/Partial Surface
Siloxanes are usually used in a sealer that is partially penetrating, and the solvent based versions are not usually safe for folks avoiding toxins/the chemically sensitive.
There are other formulas below.
Brands for the chemically sensitive:
- AFM makes a water-based acrylic blend called AFM Watershield for brick walls, natural stone showers, and concrete. This doesn’t react with the concrete to seal. It partially penetrates. It’s not for floors.
- Acri-Soy is a bio-acrylic (an acrylic made from natural soy oils). They claim this is a partial penetrating sealer. We don’t know anything more about its composition. It can be used on concrete floors, concrete countertops, brick, and concrete board. The odor when wet is similar to other acrylic products. It does not contain PFAS.
- GBS Concrete Sealer – this one claims to be a waterborne polyester polymer and polyurethane sealer that penetrates and becomes part of the concrete or brick.
Natural Oil Sealers
Tung oil is a non-conventional sealer for concrete. You would need to work with your concrete polisher to work on which stage you should add tung oil and if it’s compatible with the densifier.
I have seen it successfully used to coat unsealed concrete. You can see the process in a video here. It has been used on concrete countertops and smaller concrete objects.
If you use liquid glass first it might not penetrate. It all depends on how well/much the liquid glass was applied. To test if a surface is porous and will accept the tung oil, do a water test. If it absorbs, then the tung oil can be used. If it beads up and doesn’t absorb, then more than likely the tung oil wouldn’t work well.
Although it’s all-natural, it’s not without naturally occurring VOCs.
Linseed oil is not recommended on concrete (Paul Guyer).
Brands:
- Real Milk Paint Tung Oil – my post on linseed and tung oil goes into more detail on these natural oils.
Stains/Dyes/Pigments for Concrete Floors
You can use dyes alone as a primary coloring agent or in conjunction with acid stains, or integral color.
Concrete Dyes
A dye means there is no chemical reaction.
Solvent-Based Dyes
In solvent-based dyes, acetone is the main solvent. Usually, these would be avoided by the chemically sensitive.
Water-Based Dyes
Water-based dyes are a great option if you are concerned with health and being eco-friendly. Compared to solvent-based dyes, these are safer.
Always check out the individual brands to see what is in it and test a sample if you are chemically sensitive.
Water-based dyes will not create rich colors or hide imperfections in the concrete as well as solvent-based dyes. Though most dyes are micronized pigments that can be built up to get a good color brightness.
Water-based dyes typically come ready to use (no mixing). When polishing you can apply water-based dye. Often the densifier is applied first. Definitely discuss this early on with the contractor.
They are usually zero or low VOC.
There are some “two in ones” which are both dyes and densifiers.
Conventional Brands:
- Colors Direct Acetone Dye
- BEHR Concrete Water-Based Dye (low VOC)
Concrete Stains
Film-Forming Finishes
These are more like a paint than a dye. Film-forming stains produce a clear or pigmented coating on top of a concrete surface to add protection and color.
Because these are not integral, they can become worn down over time.
Brands for the Chemically Sensitive:
- Earth Paint NanoTech Floor Stain/Sealer – works on concrete as well as wood. This is an acrylic and polyurethane sealer. No silicones. The VOCs are listed at 95.86 g/l. I tested this product in my post on wood floor sealers. This can be used on concrete and wood countertops as well as floors.
- ECOS Solid Concrete Sealer and Semi-Transparent Concrete Sealer – These are acrylic coatings/stains. They contain PFAS.
- BioShield Aqua Resin Floor Finish – works on concrete floors as well as wood. I tested this low-odor finish on wood floors. It’s not meant for other concrete applications like countertops.
Penetrating Stains
This type of stain uses pigments that penetrate a little deeper into the concrete and bond to it.
Penetrating stains are water-based polymers that are low-VOC. They can create light translucent colors as well as bright and bold solid colors. They do not hide surface defects or flaws. They are usually acrylic.
Stains require a sealer on top if it’s not already integrated as a two-in-one product.
Brands for the Chemically Sensitive:
- SoyCrete – this soy bio-based non-toxic concrete stain is a penetrating semi-transparent non-film-forming decorative concrete stain that integrally bonds and colors porous concrete and masonry surfaces. The company claims this product is breathable. The stain creates natural and variegated effects without the use of acid stains. The odor even when wet was mild. (Top coat would be AcriSoy penetrating sealer or their Eco Poly). They do not contain PFAS.
- ColorWave – a conventional company Colors Direct, makes this penetrating water-based stain. It uses ultra-fine pigment to stain the concrete’s surface. It requires a topcoat. It’s not acrylic (I’m not sure what it is). It’s low-VOC.
Acid Stains
Acid stains chemically react with the minerals in concrete and physically etch the surface. Acid stains create mottled color tones.
Acid stains are a little more expensive than other types of stains. And although the final product is safe for the health of the occupants, the application requires more safety precautions and experience than film-forming and penetrating stains.
The acid is usually hydrochloric/muriatic acid. While this is chemically reacting the fumes are toxic. TSP is usually used at the end of the process to neutralize it. That is usually tolerated by the chemically sensitive.
The final product has no VOCs and is generally safe for the chemically sensitive. Though those in the extreme category should proceed with caution.
Ingredients in acid stains can include copper and iron oxide. The acid burns through the concrete and metallic salts cause the color change.
You still need a sealer on top.
Brands for the Chemically Sensitive:
- Lithochrome Acid Stain
Lithochrome Chemstain is a penetrating reactive acid stain that chemically combines with cured concrete to produce permanent, variegated, or translucent color effects. It is no VOC.
It works well on interior floors.
Chemstain produces concrete floors permanent weathered appearance. Like all acid stains, it colors and enhances, but will not hide the unique surface blemishes in the concrete.
- Kemiko
Kemiko Stone Tone Concrete Stain is a single component acid reactive stain.
Available in ten colors, it will not chip, fade or peel. It is low-VOC.
Kemiko also makes a low-VOC acrylic urethane sealer, Stone Tone II, to go on top. This provides protection from water, alkali, acids, UV light, and staining. It comes in gloss and satin and is non-yellowing.
Available at Green Design Center and Amazon.
Integral Pigments for Concrete
Pigments are used as integral colors mixed into the concrete while it’s still wet.
The pigments used to color concrete can be synthetic or natural mineral and metal oxides.
Metal oxides are mostly considered safe, especially since they will be in solid form once the concrete cures.
They can come in powder form or they might be mixed into a liquid.
High-quality mineral pigments should be specified.
White concrete is made from white cement, white sand, and white aggregate.
Additives to Avoid
You should specify no fly ash in your concrete mix since that often contains mercury and other harmful metals.
The percent of fly ash is often increased when the slab is expected to be polished since it darkens and hardens the slab.
Lithochrome Color Hardener is an integral pigment that contains fly ash, listed as “pozzolans, coal-ash”.
Some pigments can contain lead, arsenic, cadmium, hexavalent chromium, and aniline-based colors, which are not safe and suitable in a healthy home.
Synthetic Versus Natural Pigments
Synthetic iron oxide pigments are manufactured by using a known metal and oxidizing it in controlled conditions.
Natural iron oxides come from naturally occurring ore deposits that are mined. These ores are dried, separated, and pulverized.
Natural iron oxides come in reds, browns, black, white, and yellow ochres.
Chromium oxide is used to color concrete green. Cobalt oxide creates blue pigments. Titanium oxide is a white pigment that lightens.
The Safety of Pigments
The safety of pigments is not related to whether it’s natural or synthetic per se, but each mineral or metal should be looked at individually if you are concerned about health issues.
The metals contained in some pigments can be harmful in dry mix form (if inhaled or ingested), or in their disposal. Some may be unsafe for the environment (especially marine life) when disposed of.
Pigments can come in powder, liquid (powder mixed with water), or granular (not usually used in residential homes).
Brands for the Chemically Sensitive:
- Davis Colors – Davis Colors makes thousands of colored pigments: synthetic red, yellow, orange, brown, and black iron oxides, carbon blacks, cobalt blues, and chromium oxide greens. I tested them in already made-up concrete samples and they seemed great to me.
- US Pigments – they claim these are high-quality synthetic iron oxide pigments. Recommended for coloring ready-mix concrete and other masonry products including concrete blocks, pavement, and bricks. Use in bagged concrete, overlays, stucco, pottery, and other cementitious materials.
- Walttools – this is another brand making pigment to mix into the concrete either in the ready-mix truck or by hand. They claim they use pure natural and synthetic metal oxide pigments. It contains no fillers or extenders.
- DirectColors – sells both inorganic (iron oxides – earth tones, Tio2 – white, chrome oxide – bright green) and organic pigments (their blues for example).
Concrete-Based Terrazzo Floor
DM Terrazzo is one brand I know that uses no resin or epoxy in their terrazzo. It’s cement-based – a thin-set terrazzo installed over a slab. It’s essentially a thin layer of the concrete-based product that is then polished.
You can finish it with “grind and seal” or diamond polished, the same options as with polished concrete.
Concrete terrazzo is the traditional type of terrazzo. You can put this in an existing home because it doesn’t add too much height to the floor.
Resin-based terrazzo looks more like synthetic paint and has more components that need to offgas.
You can put a full concrete topping slab on a slab but you need 50 mm and you need to add steel. That’s a huge job. So doing a thin-set of terrazzo is a good idea if you need to cover the slab with something that doesn’t add a lot of height.
For concrete paints, including paints you can use on the floor, see my dedicated post on the topic.
Corinne Segura is an InterNACHI-certified Healthy Homes Inspector with certifications in Building Biology, Healthier Materials and Sustainable Buildings, and more. She has 10 years of experience helping others create healthy homes. You can book a consult here.
Join the top Substack on healing from MCS and mold!
Kate
Thank you for your very informative blog. What is your opinion on polyurea flooring versus epoxy? We’re finishing our basement, which is a flood risk. I’m chemically sensitive and we’ve got a kid and cats!
Corinne Segura, Building Biologist
I would not recommend either. I talk about this more in the substack article called mold preventative flooring
Kate
I found it! Unfortunately, it’s behind a paywall. We’re in an environment that doesn’t really get mold and it flooded only when our sump pump failed– are mold concerns that your only qualm with polyurea?
Robin Radillo
Hi. We are looking for a concrete sealer that is low VOC with no PFAS, not because we are chemically sensitive but because we just want as chemically free as we can get at home.
This is to prevent cat pee odors penetrating the cement in my
daughter’s bedroom before we lay carpet down. The carpet will be taped down with tape for this specific type of carpet.
Do you have any recommendations for a sealer that is not for aesthetic purposes and won’t prevent tape adhesion?
I hope this makes sense as I’m not able to scroll to review my question! Thank you, Robin
Paula Bailey
Hello, we have poured a concrete floor in a room that was “sunken” as a design feature as it consistently flooded. It is about 4 inches. It dried for a couple of months. We plan to tile in the future but not now as we will tile the whole house in a couple of years. I am having health reactions to the concrete- an asthma like reaction – lung inflammation/irritation. We have painted the floor now with Kilz paint but no improvement. You can still smell the concrete clearly. Can you recommend the next step? To get the concrete smell contained? A sealer of some kind? Thank you for your work.
Corinne Segura, Building Biologist
correct the source of the water that is entering that slab
Alex Zervo
Thanks for all the comprehensive information. I have an existing concrete basement floor that at times gets damp in spots after bad storms. I pulled up old vinyl flooring and was considering epoxy floor but after reading this article, I am worried about toxicity. I will look into polished concrete. It appears that a moisture barrier would need to be applied before concrete- should I be concerned about toxicity of the densifier and penetrating sealers used in process or moisture barrier used. I have child very sensitive to toxins and mold at home and am worried. Maybe, I should go for ceramic tiles as they do not have any of these additives?
Aoife
Hi again Corinne,
I am in Ireland and preparing my home’s concrete ground-floor for painting. It will be flat and even but rough, which I don’t mind because it will be covered in thick cotton rugs anyway. I lost the bulk of my budget through learning how toxic laminate is, so need to keep costs very low.
I have been through all paint options you recommend and wanted linseed, but it is way beyond my budget.
Would a plant-based wall-paint covered in a sealant work? If yes, can you tell me what is the technical name of the sealant I should be looking for? Liquid glass? Acrylic polyurethane?
I have found these two and would appreciate your thoughts.
Paint: https://www.ecologicalbuildingsystems.com/product/classic-wall-ceiling-paint-321-white
Sealer: https://www.smartseal.ie/internal-surfaces/concrete/concrete-sealer-internal-25-litre.htm
Thank you
Corinne Segura, Building Biologist
i would use a floor paint
Jennifer M
Thank you for all you do to keep us healthy! I really appreciate it!
I’m in the process of selecting a vendor to install concrete overlays (a thin layer of concrete over the existing concrete subfloor). One vendor recommended Xcel Surfaces THIN-SECTION OVERLAYMENT, which consists of the following.
What is the best way to determine if this is healthy? Thank you!
TEXTURE MIX- A very fine blend of silica sands, cement and special additives. Used as the scratch coat and texture coat.
2.2. ACRYLIC ADDITIVE- A 100% acrylic liquid polymer admixture for use as a bond coat and additive for Texture Mix.
2.3. DRY COLOUR- Dry colored pigment for use when integrally coloring Texture Mix.
2.4. TOP COAT- A low sheen, high-solids opaque colorant used with THIN-SECTION
OVERLAYMENT, typically seen on knockdown textures around swimming pools.
2.5. EFF-FACTOR- A specialty hybrid emulsion designed to be used as an efflorescence
inhibitor; can be used as a bond coat or sealer.
2.6. AQUA STAIN- A waterborne, translucent colorant designed for use on Xcel Surfaces overlayments and concrete surfaces
Daniel
Thanks for all you do!
FYI — The ECOS sealers (and so many others!) use PFAS.
Also wondering if you can elaborate on why siloxanes and silanes are a no-go. I haven’t been able to find any good info on why they’re problematic from a toxin perspective. As silicones, or silicone adjacent molecules, I had thought they were relatively safe?
Corinne Segura, Building Biologist
thanks just added that info to the ECOS listing. siloxanes and silanes usually solvent based
Cathy Cooke
Great article thank you! Do you have a recommendation for a garage floor? All options here appear look like smooth finishes which might be hazardous if the floor gets wet, as a garage floor might. Anything with flecks to help with grip and slipping hazards?
Corinne Segura, Building Biologist
I would not use epoxy personally, I would only use the finishes that can dry to the inside, especially in a garage floor which doesnt have the usual water proofing underneath
Ree
Hi! Thank you for the post. I have an old fireplace that is all brick. I want to do a change or at least bring it back to life. Maybe a shiner sealer, stain or white wash. What would you recommend? I want something breathable and non toxic. Thank you
Corinne Segura
Check out the article on breathable paints for the paint options. This article has the sealers.
Dropper Smith
I would just add that the claims that RadonSeal is providing any significant benefit for reducing vapor drive is suspect and should not be relied on. Read about sodium silicate sealers – the evidence is not there.
Choose a product that has test data that proves it works for the intended purpose.
Corinne Segura
I recommend it because silicates allow drying to the inside
Rob
Is there any reason I cant just leave the concrete bare, so, not sealed? I live in a slab on grade house built in the 70’s and want to rip out the carpet in the bedrooms and actually dont mind the look of bare concrete and I also kind of dont feeling like doing a bunch of work (reflooring or sealing). thanks!
Corinne
concrete dust
rob
So if I use the radon seal would that eliminate concrete dust? or what would you recommend as the least involved process? (ive got 2 kids and three jobs, so hardly any spare time 🙂 )
thanks
Corinne
you should talk to a contractor because that depends on the condition of your slab.
Lois
Corrine
GREAT website & info.
I am very chemically Sensitive & only allow Non-Toxic Environment Sensitive Products to be utilized in my Home.
I also live in a 1970’s Built Home & this Winter the Rains increased the Water Levels & I have Moisture Intrusion thru a Crack in the Slab Foundation. Some of my Beautiful Cork Tile Flooring was damaged & needs to be removed & the Concrete needs to be Sealed before any new Cork Tile Flooring can be installed.
I have been informed that the ‘Crack’ in the Concrete must be Sealed & after that Concrete Crack is Repaired, the Concrete Slab also needs to be Sealed.
My questions:
Do you have Recommendations for:
1. A Safe ‘Indoor Concrete Glue or Sealer’ for the Cracked Concrete?
2. A Safe ‘Indoor Concrete Moisture Barrier/Sealer’ for the expanse of my Concrete Floor prior to the New Replacement Cork Tiles are installed?
Thanx so much.
Blessings
Lois
Corinne Segura, Building Biologist
I haven’t written about those products yet
Kate
I didn’t see Green Building supply concrete sealer, would this be a safe option if I just want to keep my basement concrete slab as unfinished as we need to? Thank you so much!
Kate
*their penetrating concrete sealer
Corinne Segura, Building Biologist
it is in the article
Winona
Hi Corine, thank you for the great info! If remodelling a room to remove the carpet, can RadonSeal be safely used on the concrete slab floor and left as the flooring surface without any further grinding or treatments?
(aesthetics are not important, only sealing the concrete slab to be used as the flooring, so is the diamond grinding necessary before using the RadonSeal?)
Do you have any experience with RadonSeal and the amount of time it takes to cure/offgas and be tolerable for a chemically sensitive person?
Is RadonSeal the best silicate densifier for sensitive people, or do you know of better options?
Thanks!
Winona
Corinne
1) maybe, prob depends on how smooth the floor is, consult with an in person contractor
2) there is nothing to offgass
3) yes go with radon seal
Winona
Thanks so much!
Winona
Quick follow up question – is there a minimum amount of time after applying Radon Seal before the room can be lived in safely by a sensitive person?
Is the curing process known to take a particular amount of time before it (or purged contaminants) would be safe to be around?
I see these instructions on Radon Seal’s website:
‘Similarly to concrete, RadonSeal continues to react and slowly cure. The seal is about 50% effective against gases several days after application and it reaches its full strength in 60 to 90 days.’
‘ As RadonSeal begins to react and expand inside the concrete it may purge dirt, loose minerals, salts, and efflorescence to the surface for several days after application. Clean purged contaminents and efflorescence by mechanical or chemical means when necessary.’
If attempting to ready a room quickly for a sensitive person (within a few weeksif possible, is it still a feasible option to use RadonSeal and leave the surface as-is, or is a different type of flooring or sealant, or simply leaving the concrete uncoated, better to use?)
Thanks!
–
Winona
Laura A.
Hi Corrine,
I have a peripheral question, but it sounds like you of anyone can help! I am pouring concrete stairs, and am putting an incised inscription into one of the risers.
I have 3D MDF letters that will be attached to the inside of the form board. I plan to coat the form board and letters with “concrete release” before pouring.
However, I understand MDF is very absorptive and the concrete release solution might just soak into the letters.
So what I need to do is SEAL THE MDF and form board with something that does not react chemically with freshly poured concrete. Then at the last minute, I will apply the concrete release liquid.
I’m hoping to seal with something easy, like a Varathane Polyurethane spray sealant, or a quick-dry varnish product. But I need something non-reactive.
The question is: What is a good sealant for MDF that will not react to or bond with freshly poured concrete?
Thanks in advance!
Corinne
You should ask the contractor what the conventional product would be and then you can look for the non toxic alternative.
Genevieve
Hi Corinne,
Thanks for all your hard work in putting together this great website.
I have a concrete basement floor that has some existing paint on it. We are trying to sell our house tater quickly. I would like to be able to simply paint over it. (Not grind it off etc.) I have a 2 year old. Can you recommend product options?
Thanks so much,
Genevieve
Violetta Sur
I finally found a concrete polishing company I’d like to go with. They sent me the SDS sheet for the densifier. It is lithium silicate based, but my only concern is this statement:
“contain Lithium silicate nanopartical technology.”
Should I be concerned about the nano particles in this densifier product?
Violetta Sur
Is anyone able to help me out with the questions about the nano based lithium silicate as well as the sealant ingredients (my question below)? I’d love to know if there are any health risks here after the product has set/cured? I intend to start this work soon but am so torn on whether this is safe in the long term. Thanks!
Violetta Sur
I’m looking at a concrete polishing company who uses this as the finishing/sealing product. Are you able to tell me if this is safe? I don’t know anything about the ingredients used. My biggest concern is using anything that will offgas and with any carcinogenic ingredients. I have a 4 year old and don’t want to take any chances, even though we aren’t really chemically sensitive in the family. Thoughts?
https://www.mapei.com/ca/en-ca/products-and-solutions/products/detail/mapecrete-protector-ff
Jason Trihey
Violetta,
I am a concrete polishing contractor in MN. As far as the LS (Lithium silicate) densifier goes- Nano particle technology is just fancy marketing for small molecule size. This is useful so the product can penetrate deeper into the concrete pore structure. Every LS densifier I have ever seen is no voc.
The Mapecrete-protector you asked about. If you go to the link you posted, find the Safety data sheet download link, you can view any potential toxic substances required to be listed and google them. In this case it has one, 2,4,7,9-tetramethyl-5-decyne-4,7-diol. Every chemical product has an msds. This technique will empower you to research and make the best choices for you and your family.
Cheers,
Jason
Dapper Surfaces llc
nicole
Hi Corinne could you recommend a product to use for patching minor holes/cracks in concrete prior to application of one of these products please?
Corinne
I have to write a post on this. It’s not that simple because it depends on the size, debth of the crack, where it is, if there is moisture coming in and what is going over it (ie if it’s a floor, what kind of floor).
I’ve only tested Red Devil 0645 Pre-Mixed Concrete Patch which was good.
Denise
Corinne,
Hoping you may have some informed advise on a shower floor in our newly built home. We purchased this house in the late stages of build so this floor was in already. It is some type of concrete, different shades of stones are visible and it does not have a shiny finish, but flat/matte appearance. We had the builder return and put another coat of ?some kind of sealer on it a few months ago because it appeared to be holding moisture, taking days to look uniformly dry. However, it seems to be doing the same thing again. It is also ‘holding’ the pinkish/orange stain of our iron rich well water especially near the drain where the H20 sits the longest. ( a photo may be more helpful than my description-not sure if I can attach here). Anyway, I am highly concerned about the possibility of mold (suffered mycotoxin illness a few years back from mold in wall of our condo). Can you recommend a nontoxic sealant? I don’t care about the look-just want it sealed correctly. Thank you for your time.
Violet
I just renovated my basement completely and poured brand new concrete. We now want to do the diamond grind with densifier to get a polished, high gloss look. Does this ensure the safest, chemical free option? I have a 4 year old and I want to make it as close to 100% non toxic in that basement floor as possible. What can I ask companies/contractors that do this type of work to ensure that, and is this in fact the best non toxic option for a basement floor (I also want to ensure nothing off gasses/releases any toxins or chemicals in the future, including any concrete dust/particles into the air)?
Corinne
yes that is the best option. ask them if they are doing a topcoat.
Tara
Thanks for all of this great information. We are looking to do microtopping application for our floor and walls. What would you say is less toxic as a sealer? Water-based polyurethane or epoxy resin?
Corinne
Water based polyurethane in a low or ideally 0 voc formula is definitely less toxic than epoxy which is always harsh when wet and takes time to fully react and become benign.
Jen
Hi Corinne!
Thank you so much for this creating this site of valuable information, especially for us sensitive folks!
Regarding leaving a concrete slab plain, after a carpet is removed. Would you advise not sleeping in the room at all until this Radon seal is applied? Is the concrete dust that much of a concern, or is it more so over time, it can be an issue? I did read that plain concrete is hard to keep clean and will easily collect dust dirt etc. Will applying Radonseal help to minimize some of the challenges with dust, dirt collecting on concrete?
We have a complicated issue bc we are in Florida, and the house does tend to have some moisture issues. We are finally having 25 year old carpet removed, as I know this has been contributing to my sinus issues. My mom wants to keep the concrete slabs for now in the 2 bedrooms which I use. She wants to re-do all the floors in 1-2 years, and would like to avoid laying temporary flooring, if possible. Also, we would like to assess the concrete slabs to see if they develop any moisture issues, as we would like to know if that is one of the reasons it gets more humid in those 2 rooms. The carpets have felt moist off and on, during very humid times and if doors were closed and if an item was plastic and/or heavy, it would sometimes be moist underneath. One possibility people have said is that they never laid the vapor barrier under the cement slab. If moisture does show on the cement, we will need to figure out what to do to avoid having continued moisture issues, which could lead to mold. I see you don’t usually recommend doing a vapor barrier or epoxy?
Looks like this radonSeal may be a good option to start with that over the concrete?
Thank you for any guidance you may have.
Jen
Corinne Segura
concrete dust is a problem. you can use radon seal and that will work well if your slab is in good condition and smooth already. There are may variables to this including concrete flaws, overwatering, and laitance layers. Generally speaking, RadonSeal will eliminating dust and harden the surface. A harder surface is less prone to dusting.
if your radon seal is not enough you need a polyurethane/polyester coating on top.
Jen
Thank you so much Corinne!
After researching this class of concrete sealers “densifiers” similar to radon seal. I came across this one called “Bone Dry”, curious if you have heard of it or think it’s safe to use for sensitive people.
They state it’s “zero VOC’s, orderless, non-toxic “.
Description :
A water-based, penetrating concrete sealer, Bone Dry Pro formula penetrates through the concrete surface, fills the capillaries in the slab, and produces a barrier within the concrete. The result is a permanent waterproof barrier protecting the floor coverings from moisture damage. Properly applied, Bone Dry prevents moisture-based failures with its 20 year warranty.
https://www.bonedryproducts.com
This one has “anti microbial” properties https://www.bonedryproducts.com/P/22/AntimicrobialSealer
We are working with a contractor, and working to address outdoor moisture, as that may be part if the issue. So we were looking for something effective at hopefully repairing some of the moisture issues. This one also can be done in one day. You can prep with their primer called etch a Crete which apparently kind of exfoliates and preps the concrete for the sealer immediately after.
Thanks for any feedback you may have!
Concrete is complex lol!
Corinne Segura, Building Biologist
if its sodium silicate and or potassium silicate then it’s totally safe
Jen
Hi Corinne! Thanks to your advice, I have kept examining the concrete slab & had contractors assess, and it does appear there is more moisture in the slab then there should be, so far mostly showing under a piece of plastic duct taped to the concrete. We are hoping it’s just wicking and not hydrostatic pressure. We are exploring how to address the root cause via drainage, exterior waterproofing etc., but In the meantime, we are having the carpets removed due to mold (not black mold) in these two problem rooms (where the slab appears to get moist under some conditions) & we are having remediation done by professionals. My main concern is if there is moisture in the slab will the penetrating concrete sealers be successful or will we have issues with it bonding? We think we will try the bone dry product first and see what happens. Will polyurethane be okay to layer over that if needed, even if there is still some moisture wicking? If both of those fail, what would be your backup until we can get the moisture fully resolved, so that hopefully the room is okay enough to sleep in, Since unsealed concrete is not safe. Would “self-leveling “ cement be needed or helpful in this situation? Or some type of waterproof flooring with a floating floor? Thank you so much.
Corinne Segura, Building Biologist
whether you can use a topcial coating like polyurethane depends on the exact moisture content measurement of your floor. i would stick to the polishing the floor with the silicates to keep it the most breathable possible
Scott
Hi Corrine, what is the most viable option for grinding to remove an existing (poorly done) epoxy coating on a residential garage floor? Grind and reseal with a topical option, or grind and add a penetrating densifier? Any concerns of residual epoxy dust? Thank you!
Concrete Sealing Bay Area SF
Thank you for sharing this informative article about concrete sealing. I hope there are a lot of concrete contractors who could read this and be guided accordingly.
Ali
Hi Corrine,
We want to grind down existing concrete floors and either add an overlay + sealant or just sealant, depending on cracks. For a sealer we are looking at AFM Safecoat or Westcoat Sealer. Both matte. For an overlay we are looking at Maipai Novoplan 2 Plus. We want as non toxic as possible. We have researched the ingredients and all appear ok but would love your thoughts. Thanks!
Lucia Fischer
Hi Corinne,
Thanks so much for this post! I found it very informative and helpful. We sealed the concrete floor in our house with tung oil when we built three years ago but have unfortunately been unhappy with the results. We have had issues with rising damp and the floor feels damp and tacky during wet weather periods. My husband, who is also our builder, thinks we should seal it properly with a solvent sealer. I couldn’t see any recommendations for solvent sealers in the article. Would you happen to have any? My husband has found a product he wants to use, it’s called TOTALLY DEFEND ‐ TDISE, but I am extra weary of it as our young family will be living in the house while it is being used. Thanks so much for your help.
Corinne
ah, well rising moisture will destroy almost any finish. I would fix that if you can from the exterior, if it cant be fixed because the problem is under the slab I would still want to keep that breathable though some would go in with the most watertight option transferring the moisture problem to another level.
Paul
Thanks for this article. Trying to choose a concrete sealer for the garage floor. I called AFM Safecoat but none of their sealers are suitable for use on a floor used for vehicle storage. I can ventilate the space well and it should be air sealed from the house, but I’d still like to use an environmentally friendly product low in VOCs. Any suggestions? Thank you
Lauren
Hi Corinne,
We’re looking at concrete sealers for exposed concrete slab flooring we’re getting done (having vinyl removed and the slab grinded in our 1970s house in Perth Australia). Looking for a sealer you can still ground through as per unsealed concrete (i.e. connecting to the earths energy). And one that is also low tox and environmentally friendly. We’ve found this one which we know we have to regularly reapply:
https://www.bauwerk.com.au/au/concrete-sealer
Wondering if you have any thoughts on it.
We’re also looking at which I don’t think you need to reapply as much:
https://www.livos.com.au/products/product/kunos-natural-oil-sealer-244
If you have any thoughts or know of any other sealers that allow grounding through concrete and are low tox/environmentally friendly that’d be great.
Thanks,
Lauren
Corinne
I think a natural oil is a good idea. I like tung.
Jason
Any thoughts on concrete patch products? What should one do if patch work is needed inside for a concrete slab?
Corinne
I have to write a post on this. It’s not that simple because it depends on the size, debth of the crack, where it is, if there is moisture coming in and what is going over it (ie if it’s a floor, what kind of floor).
Julie
Yes, I cannot find a safe concrete patch, please advise.
Corinne
I’ve only tested Red Devil 0645 Pre-Mixed Concrete Patch which was good. But it’s complicated as I mentioned in the comment above.
Lisa
We are about to start building our house and my contractor told me that the city requires a pre-treatment insecticide before pouring the concrete slab. We are planning on having polished and sealed concrete floors throughout. Will the sealer contain and keep those chemicals from seeping into the house through the concrete?? I’m worried about that smell getting in.
Mary
Hi! Can you tell me anything about Diamatic Ultraflor Flor-Sil and Flor-Finish? I have a local concrete polisher using these and said they are “non toxic”. Any help would so helpful! Thank you so much for all the information you provide.
Jules
Hi Corrine,
Any tips/recommended (UK) products for dealing with decades old suspected VOC off-gassing concrete floor with cement screed, short of excavating? Several coats of ‘Deodourising Satin – Molecular Sieve Paint’ has been suggested as one blocking and absorption option, but perhaps there’s something else that should be used instead/in combination (e.g. penetrating densifier/sealer).
Thank you for your time, and for all your hard work on this excellent website!
Corinne
I haven’t seen anything that is offgassng from a concrete floor for that long. What is it that is offgassing there?
Jules
Not sure, but suspect it’s the screed. Any thoughts greatly appreciated if you have any related knowledge/experience. Thank you.
neetu
I bought a new construction house, and it smells pathetic in there.
The paint, unsealed wood floors, cabinet stains, uhhh.
I need help with quick offgassing as we are moving soon.
What can I do after moving regarding the wood floors and cabinets.
Also, I am keen on sealing the garage or making it even better, but cant seem to find anything nontoxic in stores closeby. Acrylic sealers you mentioned in your posts, are not recommended for garage.
I see some low VOC epoxy, but cant be purchased locally.
any suggestions on any home depot or lowes brands ?
Corinne
Hi, here is a post on offgassing new homes https://www.mychemicalfreehouse.net/2019/05/mitigating-sealing-remediating.html
I wouldn’t use epoxy on a concrete slab as they block too much moisture.
Antonio
Hi Corinne,
Thanks for your great article. In your guide to Non-toxic flooring you talk about the Retroplate system, but in this one you don’t mention it, is it a system that you recommend? As I probably could get it in Portugal. I am about to start the build of a new home in Portugal and I plan to use polished concrete flooring throughout the Kitchen and Living room. We want to achieve a beige tonality, what do you recommend in terms of sealer and pigment?
Thanks so much.
Corinne
It’s just one example of a brand that using the silicates for polishing. Often a topcoat is added on top and pigments can be added to the cement. Those are listed here too.
Sara
I am also in Portugal looking into this option. Are you satisfied with it? did they add an extra sealer because to protect from the water in the kitchen?
thanks
Sara
Corinne Segura, Building Biologist
the topcoat is more to protect from oils
Patti
Hi,
I am wondering what you might suggest to seal concrete candle vessels. Is there a product that is non- flammable, heat resistant and does not emit toxins? I’ve been searching for awhile and haven’t found much luck. In searching for a natural product, linseed and kerosene come up, both flammable. Any suggestions would be greatly appreciated!
Patti
Peter
hi Patty, I am dealing with the same problem. Would love to hear any suggestions on non- flammable, heat resistant and toxins free sealent.
Corinne
The drying oils are fine once they are totally cured. Tung oil could work well but test it for the look that it gives on concrete and of course make sure it’s totally cured before using the candle.
Dine
Hi good day,got your luck to find the sealer for concrete vessel for the candle?EARTH AND SAFE FINISHES,is on viral now,but unfortunately is not available here in my location,
Jason Trihey
Corinne,
I own a concrete polishing/staining business in MN. I strive to be near Zero VOC in all of my product offerings. I really liked your article! You must have really done your research or consulted with someone in the industry. So many articles I read online about concrete floor finishes are extremely outdated or factually inaccurate and only further reinforce common misconceptions about them. Your article was overall very accurate.
Corinne
Thanks jason, tonne of research for this one! I would love to talk to someone directly with practical hands on experience if you are up for it!
Jason Trihey
Sorry for not replying sooner. I’m more than happy to share my experience or answer any questions you may have. Look me up
Dapper Surfaces, Rochester, MN
Robin Schwartz
Hi. Can you recommend a densifier with 0 VOC?
Corinne
I believe Radon Seal has no additives.
Robin Schwartz
Thank you
Jason Trihey
All concrete densifiers are 0 VOC unless they are a dual purpose product that contains a combination of 0 voc densifier + some other formulation such as an acrylic emulsion, silane, silicone, siloxane, etc… Reference technical data sheet (TDS) and or safety data sheet (SDS) to confirm.
Jason Trihey
All densifiers are 0 VOC. They are simply aqueous silicate solutions. They are highly alkaline though so you should wear gloves and safety glasses if you are going to apply them.
Nancy Ross
I am sealing the floor in my basement storage area. Which of your choices would be best? Was wondering if you ever researched Trojan Masonary and Concrete sealer.
Also we are doing polished concrete in the remaining living area of our basement. Trying to keep our home healthy as possible,
Corinne
I haven’t tested that one, looks very non-toxic though. I would ask about the perm rating or see if you can find it in the specs.
Carly Swift
Hi,
I’m needing to remove peeling paint from my basement and am trying to decide on what to do after. We do not have good ventilation in our basement. I need to reseal it too because of cracks from ground pressure. I was concerned about resealants. Is that what the tung oil or water based sealants can be used as a resealant?
Thanks for your post
Corinne
Yes, I like many of these water based sealants I have tested most of them and they were low odor and quick to cure.
Kristine Deininger
When you say “these” in the post above, what is being referenced? I might have missed the link…
Corinne
I don’t think there are any links missing but I’m also not sure which sentence you are referring to.