Whether you need a grout sealer depends very much on the situation. A grout sealer could actually do more harm than good.
For that reason, I will list out the non-toxic sealer options by application and then by type of sealer.
The densifiers are the most tolerable least toxic option, they are a very benign product. Topcoats of acrylic or polyurethane do have some odor and offgassing at first, but the offgassing comes to completion in a short time.
There is also the possibility of going with a natural product, some natural penetrating oils can be used on concrete grout.
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1. To Seal Grout in Tiled Showers
In wet areas, you generally want to use a breathable sealer if one at all.
Both Mike Holmes and Cheryl Ciecko recommend not sealing the grout so that it is breathable and allows water to dry out to the inside. Your waterproofing is done behind the tile.
You can keep the grout unsealed. If you must seal it, use a “liquid glass” densifier sealer which still allows some breathability.
AFM Grout Sealer is one option, It’s zero-VOC and is one of AFM’s most tolerated products. It has almost no odor at all even when wet. This is a potassium silicate product also known as a liquid glass densifier. It does not change the look of the grout at all.
A densifier makes it easier to clean and less likely for dirt, grime, and mold to get embedded. It’s not intended to be waterproof.
You could use a DIY/homemade option by buying liquid glass and applying this. However, I would caution against that because it’s easy to end up with a white film if you buy just any liquid glass. I would buy AFM Grout Sealer, or another brand made for grout, and follow their instructions so you get a even (and invisible) finish.
2. To Seal Grout on Tiled Floors
If your tiled floor is on a concrete slab (on grade or below grade) then Cheryl Ciecko and Mike Holmes also recommend keeping that breathable so that the concrete can dry to the inside. It’s nest not to seal it.
You can use AFM Grout Sealer which is breathable and a no VOC product that does not change the look of concrete-based grout at all.
If your tiled floor is on an upper level of a house or apartment building and the floor below is the same temperature (more or less) as your space then it’s less risky to use tile sealer that blocks moisture. (If your tiled floor is a bathroom floor then it should be left without a sealer for maximum breathability).
You can still use a densifier but you can also use:
ECOS Stone Sealer
ECOS, a well-liked brand, has a stone sealer that is used on grout. They do not disclose any of the ingredients in this product so it’s not possible to know how breathable it is exactly. It is zero VOC.
AFM Safeseal is an acrylic coating that can be mixed into a dry mix concrete grout (with the water) instead of adding a topical grout sealer.
For a strong topcoat sealer, you can also use a water-based polyurethane like Earthpaint Nanotech.
You can also use a natural oil on concrete-based grout. I have been experimenting with 100% natural tung oil and have so far have liked the effect. It certainly darkens the concrete by quite a bit.
3. To Seal Tile on a Backsplash
You don’t necessarily need to seal grout on a backsplash since it doesn’t usually get that damaged. But if you do want to seal it that can provide some stain proofing.
If your tiled wall is on an exterior wall and you use AC inside the wall should be kept breathable, and don’t seal it.
Use AFM Grout Sealer.
Acrylic and Polyurethane Sealers
If your tiled wall is not on an exterior wall, or you don’t use AC inside you could use a densifier or something that blocks more moisture like ECOS Stone Sealer, Safeseal mixed into the dry powder at the time of application, or Earthpaint Nanotech.
All Natural Sealer
You can also use a natural oil on concrete-based grout. 100% natural tung oil leaves the grout partially breathable (similar to densifiers) but darkens the look quite a bit. It takes some time to fully cure but provides good protection against stains, especially oil stains.
4. To Seal Tiles on a Countertop
In this scenario, use a dark colored group. Mike Holmes recommends not sealing even on a countertop. However it is the least risky place to seal.
If you can, mix an integral sealer like AFM Safeseal into the dry mix grout and follow that with a topical coating like Earthpaint Nanotech. If that is not possible use AFM Grout Sealer first, followed by Nanotech.
The Natural Option
You can also go all natural with pure tung oil. This darkens the look of the concrete-based grout and will certainly give you particularly good protection from oil-based stains. Tung oil is really quite durable for a natural choice. You cannot use a synthetic sealer over this, and it likely won’t work over a synthetic sealer since it needs to soak in to work.
Choosing non-toxic grout and mortar
Non-toxic waterproofing in bathrooms
Corinne Segura is a Building Biologist Practitioner with 8 years of experience helping others create healthy homes.
CAROLE J ROSEN says
Thank you so much for all the great work you are doing! SO helpful! Much appreciated.
I am searching with little luck for a bathroom floor tile colorant and sealer in white which is non toxic. The guy cleaning the floors uses Ultra Care Grout Refresh, Universal Grout Colorant and Sealer (WHITE) which is advertised as “eco friendly” on Amazon but if you read their SDS it is full of toxins and carcinogens. Any suggestions ?- He insists on white colorant not clear. I have found non toxic replacements for pretty much everything during this home renovation but this one is stumping me! Carole
bathroom tile grout should not be sealed according to mike Holmes, Cheryl ciecko and me. It needs to retain its ability to dry out. As for the SDS I don’t see any real life hazards there, titanium dioxide needs to be inhaled or injested, and silica or quartz need to be inhaled to be a hazard and this is a liquid product. It’s not ultra low VOC and verges on not being low VOC so that will be up to you.
John Dallmus says
I used a tile grout that is not agreeing with me. It is in a bedroom. What sealer do you suggest when the intent is to seal the grout from off-gassing?
John Dallmus says
I should have noted that the tile is ceramic.
what kind of grout is it? find out the exact kind and ask the manufacturer if it can be sealed first.
if it’s a concrete based grout you can use Earthpaint Nanotech. I would only seal grout if there is no chance of the tiles getting very wet since grout usually needs to stay breathable to let water dry back up.
Mary Torres says
You mention that AFM Safe Seal could be added to dry grout along with the water to help make the grout more waterproof and more stain proof. Could you suggest how much seal to add to a 10 pound bag of dry grout?
Rachel Quigley says
I think I found another good stone, tile, and grout sealer that you might want to add to the list. Do you know anything about it? No VOCs, solvents, flurochemicals, etc. Small family company. I have not tried it yet. I’m choosing between this and AFM Grout Sealer.
I see on the TileLab Grout Sealer Safety Data Sheet that there appears to be at least some flurochemicals which are highly toxic.
That one doesn’t say what is in it though. Maybe you have to email them for a SDS. In almost all cases AFM is what you want to use to keep it breathable.
Rachel Quigley says
They would not send me their SDS until I told them the government requires them to provide it to the public! It’s a little vague, like I wish they named the actual active chemical. They told me it bonds completely to the grout or stone and is food-safe for countertops. I’ll let you decide if it’s worth including it on your list. I give them credit for no odor or flurochemicals. Oh, I don’t see a way to attach a document, but I can email it to you if you are interested.
P.S. If you need a payment to answer my question I posted about the kitchen cabinet finish called Gemini, I will be happy to pay you because I need to know the answer. Thanks!
HI Corrine, Is the Vinyl Legends of Cali Bamboo one of your recommendations? I do not know how to interpret the test results, and I am concerned about the chemicals in this LVP..
I have a post on vinyl plank flooring