Oil-based stain can be kept for 1 year if the cans have been opened, but unopened cans will last 2 - 3 yrs. Water-based stain will last 1 year, if opened, and 2 years, if unopened. Oil-based varnishes will be good for 1 year, opened or unopened.
But staining is scary because it is permanent, so you have to be careful.
Stain Application Frequency
Exterior deck stains last longest when they cover the most wood grain. Sunshine, specifically UV rays, and rain wear down a protective stain. Although some stains may last longer, in general, you'll need to re-stain your deck every 2 or 3 years.
Types of Stains
Semi-opaque stains hide much of the wood grain beneath wood pigment; however, these last longer and should be reapplied every 3-4 years. Solid or opaque stains have the riches color and hide the grain the most. These last the longest, needing reapplication about every 4-5 years.
Many, probably most, store-bought stains are made with both dye and pigment. If wood stained with these stains is exposed to sunlight or fluorescent light for a while, the dye color will fade away, but the pigment color will remain.
Colgate® Optic White® Pro Series Whitening Toothpaste can remove up to 15 years of stains, when users brush twice daily for 2 weeks.
The age of the stain often determines whether it's removable or not. If treated quickly enough, in the hands of a trained professional, almost any stain can be removed from almost any fabric. Unfortunately, the opposite is true. Given enough time, an otherwise removable stain can cause permanent damage to the fabric.
The Cons of Staining Wood
While some stains can last up to five years, postponing re-staining a wood surface for too long can cause the job to become more complex and labour intensive. Even decks that are stripped and re-stained will still require maintenance every couple of years.
To properly answer your question of “Do you have to seal stained wood?”, the answer is no. However, if you want to protect your wood and give it a polished finish, it's smart to do so. It's worth taking the extra steps and applying a wood stain sealer.
Staining over stain is easy and works beautifully if you're applying a dark stain over a lighter stain on the wood. Remember, it's the same principle as dying your hair! This rule applies to oil-based stains, water-based stains, and gel stains.
A change in texture is the biggest visible sign that something has gone wrong. Traditional wood stain should still be a liquid. Gel stain should still be a pudding-like texture. Any indication that the stain has separated, turned stringy, dried up, or had any other change in texture is a sign that it's gone bad.
Wood stain won't adhere well to damp wood and can crack and peel. Apply stain to dry wood when it hasn't rained for several days and the forecast calls for at least two days of dry weather between 50° F and 90° F.
Typically, homeowners should restain horizontal surfaces such as decks every two to three years.
Paint sits on top of the wood and can hide imperfections better than stain can. This means if the wood on your home is old or not attractive, the paint will help cover it up. No paint is perfect, though – if your wood needs replacing, paint cannot make it look new.
Outdoor wood stains are water repellant, so they make the wood waterproof, that is protecting it against water and, as a result, against mold. The only problem is that it is a short-term protection. As the stain wears out, the water easily finds a tiny crack to penetrate the wood.
Sand out the stain
If you are looking to save some time, then a much easier option is to use an orbital or belt sander. Once you've finished machine sanding, we recommend you sand by hand with the grain of the wood using the same grit sandpaper you were using in the machine. This will erase any machine marks.
A polyurethane top coat protects the wood from scratches, stains and water damage. A Spar Varnish should be used on outdoor wood to protect it from weather damage and UV rays.
We always recommend two coats of stain for any wood project, but you should only apply as much stain as the wood can absorb. Extremely dense hardwoods may only be able to absorb one coat of wood stain. The general rule of thumb is to apply only as much deck stain as the wood can absorb.
Water-based stains need to be stripped off before you apply a new finish, while oil-based stains can be recoated after you use a deck cleaner. To test the stain: Apply a small amount of deck stripper to a small area on your deck. Let it sit for about 15 minutes, then wipe it off with a cleaning rag.
With staining, you'll know if you've over-applied your deck stain because there will be sticky patches or puddles that just aren't drying—the wood has absorbed all it can, so the remaining stain has nowhere to go.
It is better to stain your deck if you want a natural look and paint your deck if you want to add color. Stain is easier to apply and easier on the wood, but painting gives a more protective barrier and lasts longer.
Oil-based wood stains are the most popular choice when it comes to choosing a stain, due to their durability and deep penetration.
Make a paste using equal parts baking soda and hydrogen peroxide. Cover the stain and let it sit for over an hour in direct sunlight. At this point, check your progress to see how much of a dent you've made in the stain. Continue to let sit, then hand wash or launder according to care instructions.
The longer a stain is left untreated, the less likely it is to be removed. When a spill first occurs, it sits on the surface of the fabric, but over time, that spill can start to react with the fabric causing the fabric to actually change colors.
Curry Stain
Turmeric in curry powder is the key culprit that can cause your soft furnishing to be permanently stained if curry gravy is spilled.