Last Updated on August 30, 2023 by Ernest Godia
How often do you remain with leftover stains after finishing your wood projects and wonder what to do with them? Do you store them or throw them away? If you decide to store them, for how long can you do so?
Wood stains can last as long as decades when stored under the right conditions. As a DIY woodworker, you may have some leftover stain in the garage and wonder, does wood stain go bad?
If you’re in this situation, read on to understand the conditions that can make your wood stain go bad and how you can store it properly for longer shelf life.
Does Wood Stain Go Bad?
Yes, wood stain goes bad if it stays too long and if kept under conditions that make it vulnerable. Some conditions that make the wood stain go bad include exposure to air, moisture, bacteria, and extreme temperatures.
Wood stain goes bad faster when opened than when it remains unopened. Always consider storing stains under air-tight containers to prevent them from going bad fast.
Does Wood Stain Go Bad in The Can?
Yes, canned wood stain can go bad if it reaches its expiry. If your wood stain stays enclosed in the can for three to five years without being used, it may expire and become unfit for use.
Note that canned stains that have been opened before can go bad faster than unopened ones. Opening the can exposes the stain to bacteria, air, and moisture, which lowers its shelf-life.
It is, therefore, advisable to carefully reseal any opened stain cans so that they are airtight to make them last longer.
What Makes Canned Wood Stain Go Bad?
Canned wood stain often goes bad due to improper storage conditions such as exposure to moisture and unfavorable temperatures. Opening a can and not properly resealing it allows moisture, air, and bacteria to enter and render the stain useless.
If you read the storage instructions on stain cans, you’ll find that most manufacturers instruct you to store your stain in a cool and dry place. This is because moisture or humidity is not friendly to wood stains.
Storing canned stains in a moist place reduces their shelf life by diluting the stain pigments. Even though an unopened stain has a longer shelf-life than an opened stain, you can make it stay for as long as 20 years by storing it in a moisture-free area.
Canned wood stains should not be stored in an area of extremely low or high temperatures. Extreme temperature conditions affect the shelf life of wood stains, even if the can is unopened.
Water-based stains are more affected by these conditions compared to oil-based stains. When stored in a room that’s too cold, the water in water-based stains tends to freeze, causing the stain to harden.
On the other hand, oil-based stains only get thicker when stored under low temperatures.
What’s the Shelf Life of Wood Stain?
Most wood stain manufacturers suggest a shelf-life of three years. However, they can stay longer when stored under optimum conditions, and the can remains tightly closed.
Different types of stains also have different shelf lives as follows:
1. Oil-based Wood Stain Shelf Life
The estimated shelf-life of oil-based stains is three years. However, a new, unopened stain can last six months before starting to go bad. Once the can is open, the stain absorbs air, and its shelf-life significantly reduces.
Oil-based stains have metallic salts and thickening agents, which accelerate oxidation when the stain comes into contact with air.
2. Water-based Wood Stain Shelf Life
Like oil-based stains, water-based stains have a shelf-life of three years when new. These stains are more affected by environmental conditions and can’t last so long after opening.
They are also highly volatile and do not have binders, making them vulnerable to high temperatures.
However, don’t throw your water-based stains away just because they’ve stayed for three years. Often, they are still in good condition one year after the expiry date.
3. Varnish Stains Shelf Life
Varnish stains have a resin binding agent and an oil base. These stains, therefore, exhibit a longer lifespan than oil-based or water-based stains. They can go for as long as a decade or two without going bad.
However, when the can is open, the stain components break down faster, reducing the lifespan of varnish stains.
The table below shows the estimated shelf lives of other types of wood stain
|Type of Stain||Shelf-life|
|Gel stain||3 years|
|Oil-based stain + Poly||5 years|
|Water-based stain + Poly||3 years|
How to Find Wood Stain Shelf Life
The easiest way to determine the shelf life of wood stains and finishes is to check the technical data sheets (TDS) that come with the product. The technical data sheet is a document with all relevant information regarding a product like wood stains and finishes that the manufacturer provides with the product.
Because technical data sheets list all the relevant information about a product, they are the ideal place to look for the shelf life of the respective wood stain or finish.
Your product’s TDS should include its composition, typical applications, methods of use, operating requirements, relevant warnings, and illustrative pictures.
You can also find the information on the manufacturer’s website, as some companies (such as General Finishes) post their technical data sheets on their websites. For such brands, you can get copies of each product’s technical data sheet online.
Recommended read: Best stain for outdoor furniture.
What Makes Open Wood Stain Go Bad?
Once your wood stain can is opened, the stain is more likely to go bad than the unopened one. Opening the can exposes the stain to environmental factors, which accelerate degradation.
Some of the factors that make opened wood stain go bad fast include:
- Air: If you used your stain but did not close the can tightly, the leftover stain may go bad after some time. This is because it continuously absorbs air, and oxidation takes place, degrading the stain components. To increase the shelf-life of your stain, always reseal the can carefully to make it air-tight and avoid oxygen sipping into your stain.
- Bacteria: Exposing your opened wood stain to bacteria can make it go bad. This typically happens if you open the seal and don’t replace it properly. Bacteria slowly find their way into the container and contaminate the stain, making it unfit for use.
- Temperature: Open wood stains are significantly affected by extreme temperatures. Since the stain is no longer full, the space above it makes it vulnerable to temperature changes. For instance, too low temperatures can make the stain form crystals or a gel coat on top, which lowers its shelf life. It’s therefore advisable to store opened stains in a room with average and fairly constant temperatures.
- Moisture: Improperly sealed container lids can also expose your stain to moisture from the surrounding environment, lowering its shelf-life. Moisture tends to dilute the stain components and increase the chances of growing microorganisms. Once you open the can, always reseal it and store it in a cool and dry place to avoid moisture creeping in and cutting its shelf life.
- Light: Some stains are sensitive to light and degrade when exposed. Such stains must be stored in opaque containers and in dim-lit rooms to make them stay long before going bad.
How Can I Know If My Stain Is Bad?
Sometimes, you may not be able to tell whether your stain is still fit for use or if you need to throw it away.
Here are the three common tell-tale signs:
a) The Smell is different
Does the stain smell the same way it did when you first opened it? If it has developed a new strange smell, it’s probably time to throw it away.
Oil-based stains that are fit for use should still have the original strong smell, while water-based stains shouldn’t smell as strong. A foul smell on your stain will tell you it has gone bad.
b) The Texture has changed
A change in the texture of your stain can tell you it has gone bad. Try to stir the stain and check if it has lost its consistency. Has it separated, dried up, or turned stringy?
If it doesn’t mix properly or regain its consistency on stirring, the stain has probably gone bad and needs to be disposed of.
c) The Drying Time is too long
You can also test if your stain has gone bad by using it to stain a scrap piece of wood and see if it dries properly. Stir the stain first to mix any sunk pigments, then apply it to the scrap wood and let it sit for five minutes.
Wipe the excess and let the stain dry for 24 hours. If it dries out properly, it’s still fit for use. However, if the wood still feels wet after 24 hours or the stain sticks on your hand when you touch it, it may be time to throw it away.
If these three signs show something is wrong with your stain, don’t use it on your wood, as you may mess up your furniture or wood project. Do yourself the favor of buying a new can of stain for your staining project.
How Can I Keep Wood Stains from Going Bad?
Now that you know what makes stains go bad, here are the best practices for keeping wood stains sound for longer:
1. Get a Tight Seal
Most of the factors that make the wood stain go bad revolve around poor sealing. To prolong the lifespan of your stain, always use an air-tight seal that keeps it from absorbing moisture, air, or bacteria.
To test if the seal is tight, press the sides of the can and listen for any sound of air seeping out. If you hear no sound, the can is tightly sealed and safe for storage.
2. Store Under Steady Temperatures
Always store your stains in an area of steady temperatures to make them stay longer without going bad.
A cool room with moderate temperatures keeps stains safe and extends their shelf life. If you stay in an area that experiences extreme temperatures, you can use an A.C. to control the temperature of the room where you store your wood stains.
3. Carefully Choose Your Storage Space
Carefully choose where you store your stains to keep them away from hazards like fire. Note that wood stains are highly flammable and can easily catch fire when exposed to combustible materials.
You should also keep them away from the reach of both children and pets.
How Do I Dispose of Bad Wood Stains?
Bad wood stains can be toxic and should not be thrown in the trash. While you can dispose of a good stain by simply letting it dry, a stain that has gone bad does not dry easily. The best way to get rid of it is to drop it at your local hazardous waste disposal center.
Can You Revive Wood Stain Hardened in a Can?
No. You can’t revive hardened wood stain if all the stain has dried in the can. However, if it only dries at the top and forms a hard crust, you can revive it by adding a stain solvent. Usually, it’s the solvent-exposed to air that evaporates to form the top crust.
Add a small amount of solvent to the crust and let it sit for one hour. Use a mixing stick to mix and stir it thoroughly until the top crust dissolves and the solvent mixes with the thick stain beneath.
This should restore the stain’s texture, making it usable again.
How to Tell If Your Old Deck Stain Is Still Usable
You’ll know your old deck stain is still usable when you open it, and it smells the same way it did when new. It should also have the same original consistency and dry up well when tested on a scrap piece of wood.
Final Thoughts: Does Wood Stain Go Bad?
As a DIY woodworker, you may want to save money by storing your leftover wood stain for future use. However, wood stains go bad if not properly stored. Use the tips in this article to store your leftover stains properly and keep them from going bad fast.
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