Urethane can be stored for a long time as long as its kept dry and sealed tightly. You will know that its been contaminated or moisture got in if, when you open it, it looks like cottage cheese.
Once the finish starts curing, as it has in your case, its best to just throw it away. But, if you are feeling especially frugal, feel free to strain out the chunks and test the remaining finish on scrap. If it cures properly and seems to bind strongly to the wood, you can probably get another use out of it.
Existing polyurethane is rather famous for being impossible to repair, invisibly at least. While that exaggerates the case somewhat the fact is that once you get actual losses -- where you're back to bare wood -- there is nearly no option but to strip and refinish.
Appearance. Water-based polyurethane begins milky-white in the can but dries clear. Very little, if any, color is imparted by the water-based polyurethane.
Under normal use and regular wear and tear, we can expect a lifespan of: 50+ years for building insulation. 25+ years for refrigerators. 20+ years for car bumpers.
PU foams deteriorate rapidly; visible consequences of degradation can appear after 20–30 years of natural degradation. The main visual signs of degradation are discoloration, loss of flexibility, and crumbling, which occur under influence of moisture, heat, and light.
The Short Answer: All polyurethane will yellow over time. While modern technology has extended the amount of time it takes to yellow and reduced the extent it can yellow by, ALL polyurethane (including polyacrylics) will yellow.
Make sure to sand the polyurethane between coats. Sanding removes drips, bubbles and other uneven spots in each coat. Dry the first coat for a full 24 hours. If the coat feels tacky or sticky after that, let dry until it feels completely dry.
COLOR: Oil based poly has an amber hue, whereas water based poly is clear. An oil based polyurethane will continue to amber and darken over time, while water based poly will remain clear for the lifetime of the hardwood floor.
Here are some of the main ones: Exposure to weathering: Prolonged exposure to the sun's UV radiation, temperature variations, humidity, weathering and other atmospheric agents can affect the durability of polyurethanes.
Water-based polyurethane requires at least two hours of dry time between coats, and you should only apply two coats in a day. It's important to remember that drying time is affected by temperature and humidity.
The ideal temperature range for applying polyurethane is between 70°F and 80°F. Temperatures below 65°F can significantly extend drying time, and below 55°F, the finish may remain tacky for an extended period.
The Taber test involves two abrasive wheels that are lowered onto the specimen, and as the platform rotates, the test material begins to abrade away, and wear marks become visible. Taber abrasion is measured in mg loss. Wheel, load, and cycles to make comparisons should be noted.
Gloss oil-based varnish, polyurethane and Danish oil can last 10 or 20 years, though satin finishes and stains may fail sooner as pigments and flattening agents disable the driers. Water-based coatings and paints can also be viable longer than three years. Shellac, though, can go bad in under a year.
2️⃣ Sanding: If the cloudiness is due to improper adhesion, lightly sand the affected area with fine-grit sandpaper. This will help smooth out the surface and promote better adhesion. 3️⃣ Recoating: Apply a fresh coat of water-based polyurethane, ensuring proper mixing and application techniques.
Waterborne polyurethanes usually require a minimum of 3-4 coats to be effective. Although there is some evidence that too many coats can result in a plastic-like finish, waterborne polyesters are thinner than other types and therefore require several more coats to provide the same protection for hardwood floors.
Prepare the polyurethane by reducing it about 10 percent with mineral spirits, unless you're using water-based polyurethane, which doesn't need thinning. Thinning the polyurethane makes it flow on more smoothly and reduces brush marks. Quick Tip!
No. Urethane-based product must be sanded before anything goes on top of it. Since it is essentially plastic it requires a mechanical bond between coats.
Bubbles and streaks can ruin the smooth finish of your polyurethane floor. To avoid bubbles, make sure to stir the polyurethane gently and avoid shaking the can. When applying, use a high-quality brush or roller and apply thin, even coats.
Vinegar should never be used on polyurethane floors, for example. Because it's an acid, vinegar can eat away at hard finishes like polyurethane and wax. Use only white vinegar, diluted with water, on soft floors that are finished with an oil-based coating.
Polyurethane materials are sensitive to UV radiation, temperature and humidity, and photothermal oxidation, hydrolysis and degradation caused by heat and light accelerate the yellowing of polyurethane products.
There is no difference between the terms urethane and polyurethane. That might seem confusing, so here's a quick explanation. Polyurethane is a polymer. A polymer consists of repeating units that are chemically linked in a particular pattern.
Natural polyurethanes vary from a light tan (almost yellow) to a medium-dark amber (almost greenish). This variation is noticed from supplier to supplier, and even within a given supplier's production. Black or other colored (pigmented) polyurethanes do not typically exhibit this variability in color.
An increasingly important performance value for coated fabrics is ultraviolet (UV) light resistance. It is known that polyurethane and vinyl materials used for both interior and exterior applications are subject to photo-degradation when exposed to ultraviolet light.