All About Polyurethane

A base coat is two parts of polyurethane to one part of paint thinner. The second and third coats are applied at full strength. Polycrylic is a water-based protective finish made by Minwax. It’s ready for light handling after about three hours but needs at least 24 hours before it’s ready for “normal use”. We need to be careful during this time because it can scratch or dent before it’s fully cured.

If you wait past the window all you need to do is a light sanding with 320 grit sand paper to provide enough “tooth” for the second coat to adhere. Since a scuff sanding isn’t a bad idea anyway to keep the dust nibs and other “artifacts” at bay it’s not very important to stay within the “window”. Below, we’ve arranged these finish types with durability increasing from beginning to end.

View The Best Polyurethane, Below

Each layer must be left to dry completely before another can be applied. You can use heat or increased airflow in order to speed up the drying process between coats. Your tool must have a tip between 1 and 5 inches wide, as this is the best size for not only polyurethane but many other finishes as well.

Like spotting land after a long passage, were glad to say that the end of our long-term exterior wood finishes test is finally on the horizon. I just put 3 coats of spar urethane on a outdoor barn quilt and it is now yellow instead of white. What it all comes down to is protecting wood, and for exterior applications, spar varnish does a better job of it plain and simple. Just like you need the right tool for the right job you also need the right varnish for the right application.

Polyurethane Dos & Don’ts

The only concern with the varnish option is it tends to be a bit softer in the direct sun/heat. It may stick to your pants slightly or retain an imprint of the fabric. Based on your non-marine need, I would recommend urethane. The main goal is to protect your wooden paddle or vessel from water and weather and both of these products could help you do that. Some reviewers have remarked on the good coverage offered by this product.

Polyurethane, on the other hand, has a greater tendency to promote ultraviolet light so it will discolor your furniture. Nitrogen is vital because it will help you protect the finish from chipping, while isocyanates will create additional thickness. Here are some supplies and tools we find essential in our everyday work around the shop. We may receive a commission from sales referred by our links; however, we have carefully selected these products for their usefulness and quality. Oil-based poly will be slightly more resistant to scratches, moisture and heat when compared with water-based poly. The five-hour wait between coats and 12-hour wait after the last coat will put a bedroom out of commission for a few days.

(The table color looks dead, while the leaves are alive.) The chairs have discolored as well. I assume that one needs to first remove the epoxy coat. Hi, I have 22 exterior doors that bake in the Arizona sun. The door are made of fiberglass with a wood grain pattern molded into them.

• Le Tonkinois is the next product I intend to use if I need to finish an outdoor project.
• With a water based poly, you have unlimited coats available.
• Without describing the characteristics of lacquer and polyurethane again, let’s see how they compare with our winner.
• At the same time, this low drying time can be a problem at certain times.
• I am recommended to use a water based polyurethane to transfer a laser printed poster onto a wood.
• It is very protective and will keep your doors, floors, and furnishings in good quality for years to come.
• If you don’t like the color of the spar varathane, I’d say skip it all together.
• Another thing to keep in mind is that you generally need a lot more of Minwax’s products to complete your project.

I had a cedar deck and gazebo put in 2 years ago and gave it one coat of Sikkens SDR as it was less than 2 feet high in spots. The SDR on the horizontal surfaces exposed to sun and snow turned gray and started to crack this year so I resanded and reapplied the SDR. I would like to put something stronger that would last longer than 2 years. Are there marine products available in Canada that I could use that would not be too shiny?

This is where polyurethane comes in as it provides a clear protective coating to all of your wood furnishings and surfaces. Varnish is a mixture of a resin and a drying oil that is mixed together and then heated until it becomes a new compound called varnish. Anyway, protection isn’t the only thing to look for when chosing a finish. How it looks, how easily it applies, and how easily it can be repaired if damaged, are all quite important. In my opinion, it is the marketing hype that has pushed “poly” into dominence in the consumer market.

Its purpose is providing a protective barrier against air moisture and water exposure that would otherwise, in time, damage wood. My dilemma with choosing a finish is being caught between two conflicting interests. I desire hardness but also a little bit of UV protection. I now know that marine spar is softer to deal with the constant expansion and contraction of a boat’s life on the sea but has pretty darn good UV inhibition .

Emtech top coats are too slippery/fast, and do not meet the anti-slip properties required. Working from a separate container prevents the dust and other particles picked up by the brush from contaminating the finish in the can. Wax isn’t durable and will interfere with any subsequent coats. Thinning doesn’t improve adhesion, and you’ll have to apply more coats and use more solvent. Thick ones take longer to dry and are more likely to drip or wrinkle. 12 months – The length of time a poly should be usable after you open the can.

Typically, you will require 10% of thinner in order to reduce your polyurethane to the point that it can be used in a spray. If you have chosen to use a spray can polyurethane product, you will not need to perform this step. If, however, you plan on using normal polyurethane in a spray gun, you will need to use a thinner so as to reduce the viscosity of the liquid.

The poly depends more on a mechanical bond when recoating, whereas with the traditional, a chemical bond occurs. This simply means a scuff sanding is all you need to maintain it. The poly requires much more agressive sanding to acheive the mechanical bond needed. As you can see from this picture, the difference is pretty dramatic. The water based polyurethane is lighter and duller than the oil based poly on the right.

The product manufacture suggests sanding in attempt to let customer end up with smoother finish from sanding junk out as they go. I welcome debate as long as it is serious and is supported. I don’t always consider links as supporting evidence. Regarding the final finish of your polyurethane coating, you will once again have to decide between an oil- or water-based spray. Water-based polyurethanes are thinner and therefore require more coats. The finish will be crystal-clear and should not yellow, although it may not offer the greatest durability.

One polyurethane spray can will cover up to 25 square feet of surface, and will dry within just half an hour. You should be able to apply the next coat after just one hour. This product emits a low odor when used and will leave behind a crystal-clear finish that not only resists stains and scratches, but it will also never yellow. Oil based polyurethane lasts longer than water based.

You can also thin the water-based solution in order to improve atomization. We suggest using the vertical setting to spray surfaces such as table legs, columns, and pegs. The horizontal spray is great for moving across a flat area, whereas the circular or middle spray is ideal for covering corners, detailed curves, and edges.

Polyurethane Varnish

Some paints also contain polyurethane for extra smooth and shine. Polyurethane is used to acquire a smooth, blemish free texture on the products. Perhaps its biggest selling points, however, are that it’s lower in toxicity than its counterparts and requires only soap and water for cleanup.

Coating over it with either of those would maintain that softness/flexibility as a base coat. High End spar varnishes ( I wouldn’t use these indoors) tend to take much longer to dry and stay much more minwax vs varathane spar urethane flexible than spar urethane. As far as application, both the Cetol and PolyWhey are quick and easy to apply, with much shorter recoat times than hard varnishes and less sanding between coats.

I had several cans of different spar urethane that weren’t very old and had used on a project for a customer. The only thing you need to remember is tung oil is better than linseed oil because linseed oil will blacken over time with UV exposure where tung oil will not. Just because it contains tung oil does not mean its a superior finish.

Source: homemakerguide.com