Polyurethane vs. polycrylic

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solomonson's picture
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Joined: 2010-10-31 17:52
Polyurethane vs. polycrylic
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Forgive me if I'm beating a dead horse, I couldn't find any topics in this category that deal with this.  What do you lovely people prefer?  I hear polycrylic is better for white furniture since it doesn't yellow.  I found some Dutch Boy and some Krylon spray polycrylic that my husband happened to have.  Does anyone have any experience with the spray kind?  Is one better than the other for paint vs. stain?

OkieJoe's picture
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Joined: 2010-12-16 02:20

There are some big differences in what polycrylic, which is a water based acrylic w/a little polyurethane, and generic polyurethane finishes from a content standpoint, but for sealing/providing abrasion resistance/easier cleanup, polycrylic is a really good choice over paint. If you are staining, I'd go into more detail on what to use, but over paint polycrylic is a really good choice. It drys to touch quickly, although it won't be actually cured for a couple of days, provides good protection, and when sprayed, lays down a nice even coat that levels well. The down side to polycrylic is that you need to wait until it's cured before doing anything else to the finish <EDIT - according to the label, you can sand within a couple of hours of spraying, but you definitely need to wait before>,finish sanding or polishing. Polyurethane, which is oil based, typically imparts<EDIT allows> a slight color change to the material it's applied over. Thats usually desired in a stained finish, but not so much in a painted one. Also, polyurethane doesn't adhere as well to paint, especially latex paint, so a light (220-400 grit) sanding before applying poly is a good idea. I've never tried poly over latex, so don't have any firsthand knowledge, but a general rule I follow is to apply oil based topcoats to oil based subcoats, and water based topcoats to water based subcoats. There are exceptions, but that is a safe general rule. Finishing is a whole mystery unto itself, and one that I'm still learning, but the general rule above is a good one. Polycrylic over latex is a good finishing combo, unless you are trying for a very high gloss, polished look, which would be unusual in the kind of projects seen here. If you are working on that kind of deep, liquid finish, you probably already know more than me!

solomonson's picture
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Joined: 2010-10-31 17:52

Thanks!  I'm staining, and I don't have much experience with stain.  I'd like to hear your details you mentioned, if you have time.

OkieJoe's picture
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Joined: 2010-12-16 02:20

Glad to share what little I know. Poly, whether sprayed from can or brushed on is a solid choice over stain. It will allow the color to come through, and give a really good level of protection to your new piece. Unless you have access to (and experience with) some very expensive pro finishing equipment, poly is probably the best choice for protecting your furniture. The color changes I mentioned above are usually a result of UV rays from sunlight reacting with the finish or the wood underneath the poly, since most polyurethane doesn't contain any UV inhibitors. Clear poly finish shouldn't make a significant difference in the color of your piece. I'd plan on at least 3 coats of poly to build a nice protective finish, with a light sanding if recommened by the manufacturer between coats. Once the final coat has cured, maybe 3 or 4 days later, you may want to consider waxing the piece with a paste furniture wax, like Johnsons Paste Wax or Briwax. This will deepen the look of the finish and give the piece a 'glow', if you like that look. Good luck with your project.

solomonson's picture
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Joined: 2010-10-31 17:52

does "poly" mean -urethane or -acrylic?

OkieJoe's picture
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Joined: 2010-12-16 02:20

Guess I should have been more specific. Sorry Embarassed Polyurethane is a good choice over stain. Polycrylic will also work, but if I had a choice, I'd definitely use polyurethane. That's what I get for typing in a hurry and not re-reading my post.

solomonson's picture
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Joined: 2010-10-31 17:52

OK!  Now I can finish Smile Thanks a lot!

tnslb's picture
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Joined: 2010-09-09 11:23

Polyurethane is a good choice over oil-based stain ;)  You can do water-base over oil-base, but not oil over water.

thedabblingcrafter's picture
Joined: 2010-10-24 02:43

Just a side note, I did Polycrylic over white paint and it yellowed really really bad. I know that Polycrylic is supposed to be better over white paint, but the finish I got wasn't great. I'm trying over with some enamel this time around.

Kaybird's picture
Kaybird
Polyacrylic vs Polyurethane

I am painting furniture and read that you should seal it with a polyacrylic sealer. I use water-based polyurethane all the time on stained wood and prefer it over oil-based, but I'm still not clear on whether the polyurethane I use will create a hard, protective finish coat for PAINTED wood surfaces. Trying to find out if there's a difference in "acrylic" vs "urethane" when applying finish over paint.

claydowling's picture
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Urethane vs acrylic

Polyurethane is a rather generic term. The oil based polyurethanes use urethane resin for the coating, which is naturally yellow. Water bourn polyurethane is sometimes called polycrylic, and uses acrylic resins for the coating. Acrylic is clear, and is the same resin used for plexiglass, such as the windows around a hockey rink. It's super-tough, although not quite so strong as urethane resin.

The acrylic resin is dissolved in alcohol (I think ethelyene glycol), and that is thinned with water. The side of my Varathane can warns that this can pull up nastiness from the underlying paint or things that were sitting on the surface. Any iron components, such as from steel wool or embedded in the underlying wood, can be pulled up into the finish and will stain in ways that are undesirable for a clear finish.

There are some other tricks I discovered recently. I put a lot of effort into getting the underlying paint layer smooth, and the acrylic gave it a translucent look. The Varathane product also seems quite thick. Even though I bought a gloss finish, it does not self-level. I got better leveling with some thinning, but it seems a little fussy.

Kaybird's picture
decha vong
polycrylic vs acrylic

My Decoupage instructions call for acrylic sealer to seal the paper. Can I use polycrylic instead?

claydowling's picture
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Polycrylic for decoupage

As far as I can tell polycrylic is a product name from a single company (General Finishes). The polycrylic I bought from them was definitely a urethane and acrylic blend. I didn't notice any coloring issues, but I could smell urethane, and urethane is yellow. I'd stick to the all-acrylic products like the minwax and varathane water based polyurethane if color is a concern.

Kaybird's picture
decha vong
THANKS FOR YOUR HELP,BUT I

THANKS FOR YOUR HELP,BUT I CAN NOT FIND MINIWAX ALL ACRYLIC FINISHING.

claydowling's picture
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Minwax products

If you're determined to stick with minwax, the water based finish with the blue label is acrylic. For Varathane, the water bourne finish is acrylic. General has a spectrum of water bourne products that you'll have to choose from. In their case I know the polycrylic is a blend because I can smell the urethane, but they also have another blend with more acrylic. I haven't opened the can yet to check the smell, so I can't say if there's any urethane or not.

Kaybird's picture
Vyvyan
water base polyurethane vs. acrylic polycrylic for decoupage

I am decoupaging fabric onto artist canvas to make a floor cloth. What is the best sealer?... water base polyurethane or acrylic polycrylic ?

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Decoupag

I'm not sure that either product would be good for that, although it might be. Both products are brittle, which doesn't strike me as ideal in a floor cloth. Urethane resin is definitely harder than acrylic resin, which means it should wear better. But it's also yellow, so you'll get a distinct yellow tinge to your fabric.

solomonson's picture
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Joined: 2010-10-31 17:52
Wow! I had totally forgotten

Wow! I had totally forgotten that I submitted this thread and it was one of the first results that came up when I googled "polycrylic vs. polyurethane."

Claydowling, if you happen to come back by, this statement: "As far as I can tell polycrylic is a product name from a single company (General Finishes)" I found really intriguing, given that I see "polycrylic" everywhere. It's not a trademarked product by GF, is it?

Then today I saw that GF carried both polycrylic and water-based polyurethane. It's been over a year since I submitted this and I feel only marginally more informed since then. I've been using Minwax polycrylic in the blue can over everything since I rarely use oil-based products - I tried the kind in the spray can and nearly threw it away after the first use. Now I hear about waxes, pastes, tung oil, danish oil, etc etc etc along with all the water-based topcoat products that GF makes, and it's all really confusing.

Anyway, I'm just venting now, though would welcome anyone who can educate me on the use of waxes.

claydowling's picture
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Waxes

I know that waxes can be used as a finish, but I think it's pretty labor intensive and I know that it's quite soft without offering much protection.

I tend to use wax as a final coat over a polyurethane. It makes the surface feel nicer and I like the look.

A book I found that cleared a lot of things up for me was Wood Finishing 101. Price is pretty good right now. I paid full price for mine.

solomonson's picture
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Thanks! I'll check that out.

Thanks! I'll check that out.