This article digs into non-toxic and natural options for staining and sealing wood decks as well as most outdoor wood like fences, furniture, windows, doors, play gyms, and planters.
This post covers both water-based sealants and natural oil-based options that are either zero or low-VOC and have been vetted by the chemically sensitive.
Penetrating sealers require that older decks and outdoor wood be sanded all the way down, but the film-forming options can be applied to lightly sanded older wood.
The water-based finishes don’t work over oily dense tropical woods like Ipe, Teak, and Mahogany but the natural oil-based stains and the hybrid work well over these woods.
If you are working with pressure-treated wood, all stains require that the wood has time to dry out first which can take anywhere from 3 months to a year.
If you would like to look at wood types and other decking materials that do not require a finish like composites and even aluminum, see my post on deck materials.
- Top water-based option: Vermont Natural Coatings PolyWhey Exterior Penetrating Wood Stain
- Top oil-based option: Outdoor Defense Oil or Rubio Monocoat Hybrid Exterior
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Non-Toxic Sealants and Stains for Decks, Fences, Outdoor Furniture, Play Sets & Planters
1. Vermont Natural Coatings & Böhme – Terra Plus Exterior Deck Stain
What is it: This is a natural oil / waterborne hybrid penetrating stain. The colors are semi-transparent. It is a waterproofer with UV protection. It has better UV protection than the other options by this company.
Where to use it: On exterior decks and stairs.
Types of wood: Use on new or properly prepared decks. You can use it on Ipe, Mahogany, and Teak as well as non-tropical deck woods (be sure to talk to the company for direction). You only need a light sanding on a previously coated deck because it’s a film-forming sealant.
Specs: Low VOC. One person who was super sensitive thought this was better than PolyWhey. The company describes the smell as a sunflower or pumpkin odor, not a linseed odor.
Where to buy: Through the Vermont Natural Coatings website; sometimes on Amazon.
2. Penetrating Water Proofer Infused With Juniper
What is it: This is a water-based penetrating sealer. It does not form a film and the wood looks totally bare after applying it. The only purpose of this sealant is to provide waterproofing. It does not provide any UV or abrasion resistance. The wood will gray out naturally.
Where to use it: It is used on decks, railings, shake roofs, siding, fencing, indoor/outdoor play gyms, the exterior of planters/raised garden beds, outdoor furniture, and animal hutches/pens. It is not suitable for subterranean or submerged wood. It can be used indoors as well as outdoors. It cannot go over or under another product.
Types of wood: It can be used on new, or weather wood as well as pressure-treated wood. For pressure-treated wood allow 6-12 months before application. It can work on Teak and other oily woods and it is a good choice for cedar, pine, spruce, and fir.
Specs: It is zero-VOC and contains no solvents, dyes, biocides, or fungicides.
3. PolyWhey Exterior Penetrating Wood Stain
What is it: This is one of the most durable water-based non-toxic deck stain/sealers that I know of. This is a semi-transparent stain and topcoat sealer in one. It is a waterproofer with some UV resistance (more UV resistance the darker you go in stain color).
Where to use it: Wood siding, decks, fences, outdoor furniture, log cabins, exterior wood doors, play gyms, swing sets, beehives (it’s well-known for this application), pet hutches, barns, chicken coops, and other outdoor wood surfaces. This coating is great for the exterior of raised garden beds with AFM Dynoseal for waterproofing on the interior.
Types of wood: It can be used on new, pressure-treated, and weathered wood. Like with all deck stains, pressure-treated wood needs to dry out for 6 months to a year before application. Not for use on exotic super dense woods such as Teak, Ipe, or Garapa/Brazilian Ash.
It can be applied over older oil-based stains or finish, as well as other water-based finishes if it’s been fully sanded first so that it can penetrate into the wood. No product can go over top of this in exterior applications.
Specs: It is non-toxic, low odor, low-VOC, and contains no biocides, fungicides, or anti-microbial agents. The pigments act as natural UV inhibitors.
The folks at Green Building Supply have tested the non-toxic options on fences and found this to be as durable as oil-based stains and more conventional toxic stains/sealers.
4. AFM Safecoat EXT Exterior Polyureseal
What is it: A clear acrylic urethane coating for exterior use on wood and concrete. This is a water-resistant coating with good abrasion and UV resistance.
Where to use it: On walkways, decks, fences, floors, patios, doors, and pet cages. It can be applied to raw wood or wood stained with AFM Safecoat wood stains, as well as concrete or previously painted (with water-based paint) surfaces.
For abrasion resistance on outdoor tables, a paint and sealer combo would work well: AFM Safecoat All Purpose Exterior Satin and then AFM Safecoat EXT Exterior Polyureseal. (And if you really wanted a painted deck, this would be the only non-toxic combo to achieve that look).
Types of wood: Use on dry and absorbent wood. It can be applied to raw wood or wood stained with Safecoat DuroTone, concrete, and previously painted surfaces that are properly prepared. This product can not be used over oil-based coatings.
Specs: Low-VOC, it also can function to seal in offgassing of hazardous chemicals.
Where to buy: Through Green Design Center/Building for Health.
5. Milk Paint Outdoor Defense Oil
What is it: An all-natural oil sealer made from pure tung oil, pine oil, and zinc. Out of the natural penetrating oils, tung oil is the most durable (and also the most difficult to apply).
Where to use it: On outdoor wood like picnic tables, wooden Adirondack chairs, wood furniture, decks, siding, wood fencing, front porches, concrete patios, park benches, wooden storage sheds, wood doors, and windows. You can use it on beehives with a full 30 day cure. This is the all-natural option for sealing raised garden beds (both inside and out).
You can also use this over Milk Paint to protect it from the elements or you can mix (some) pigments into the tung oil.
Types of wood: You can use this on all wood types. Extremely dense woods such as Teak, Ipe, etc may require thinning with more (natural) solvent. Not for use over new oil-based sealers/stains or other finishes. You can use it over aged penetrating oil finishes (like aged linseed oil).
Specs: No metallic driers. Full ingredient disclosure: pure tung oil, pine oil (which acts as a solvent), and zinc. Some highly chemically sensitive folks have preferred these natural oil coatings to synthetic coatings like PolyWhey (others would find the opposite preferable). Always test for your own tolerance and I would recommend not using or being exposed to these natural solvents when they are wet if you are sensitive. My in-depth look at tung and linseed oils goes into more detail.
Where to buy: Through the Real Milk Company’s website. You can use code mychemicalfreehouse for 10% off.
6. Monocoat Hybrid Exterior Wood Protector
What is it: A modified linseed oil and wax penetrating oil finish that is applied with just one coat. It provides protection from water and UV (except for the color “Pure” which has no UV protection).
Where to use it: Wooden decks, façades, patios, shutters, portals, garden furniture, pontoons, windows, doors, etc.
Types of wood: Works well over almost all wood types including oily exotic woods (Ipe, Teak etc).
Specs: Solvent-free, technically 0-VOC because it’s a natural product. Though see my in-depth review of Rubio Monocoat and other linseed oils for information on naturally occurring VOCs. Rubio Monocoat is preferred to plain linseed oil in many ways because it’s lower in odor. You need a part B accelerator, be sure to test that out as well.
Where to buy: Directly through their website.
Cleaning and Reviving Your Wood Deck
To remove green algae, moss, dirt stains, and graying from wood prior to staining and sealing your deck or other outdoor wood you can use Rubio Exterior Wood Cleaner.
Use this before applying water-based stains like Vermont Natural Coatings PolyWhey Exterior Penetrating Stain or oil-based finishes like Monocoat Hybrid Exterior Protector.
One sensitive person described the feel as a light soap but with almost no odor.
Looking for non-toxic exterior paints? This post goes over the options.
For a review of deck materials – alternatives to pressure-treated wood, low odor woods, wood that doesn’t need a sealant, and non-wood alternatives, see this post on decking materials.
Corinne Segura is a Building Biologist Practitioner with 7 years of experience helping others create healthy homes.
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