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Polyurethane question

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Forum topic by Jon Anderson posted 01-22-2017 11:34 PM 543 views 0 times favorited 6 replies Add to Favorites Watch
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Jon Anderson

31 posts in 2166 days


01-22-2017 11:34 PM

Topic tags/keywords: question finishing

I have heard that you can use semi gloss and finish with one coat of Gloss and it ends up a gloss finish. I also have heard that the same can’t be said for satin because their is silica in it to dull the finish so putting the clear over it won’t make it a clear finish. Actually thats a question, even though it doesn’t look like one.

-- jbander


6 replies so far

View Mark Kornell's profile

Mark Kornell

1169 posts in 2365 days


#1 posted 01-23-2017 12:13 AM

True, sort of. Semi gloss also has a flattener in it, just not as much as matte. The purpose of the flattener is to make the surface less than perfectly flat, so that light is reflected unevenly. The more flattener in the mix, the less glossy the finish. So when you put a gloss finish over top, the new surface will be flat again, and give the piece a glossy appearance.

But the flattener is still (buried) in the finish and occludes perfect light transmission. The more flattener, the more cloudy the result. So, yes, a matte under gloss will be cloudier that a semi under gloss. But both would be cloudier than if it was all gloss.

-- Mark Kornell, Kornell Wood Design

View JBrow's profile

JBrow

1273 posts in 754 days


#2 posted 01-23-2017 12:40 AM

Jon Anderson,

I have heard of gloss polyurethane base coats for durability and then a top coat of semi-gloss or satin to tone down the sheen. It seems that if a gloss finish is desired, all coats would be gloss. I would think, as Mark Kornell suggests, that if a gloss coat is applied over semi-gloss or satin, the surface would be more reflective but the wood grain would become fuzzy looking (as in a slightly out of focus photograph) and obscured.

If this is about a project already done but the sheen is a bit too flat, it might be best to experiment with a sample board before applying the gloss to the entire project.

View Rich's profile

Rich

1976 posts in 424 days


#3 posted 01-23-2017 04:07 AM

The last coat is what you get in terms of light reflection. So, yeah, if the top coat is gloss, it’s going to be a gloss finish.

The only time this is useful is if you want to build up a satin finish. Using gloss for all but the final coat or two will supposedly give you a clearer finish that lets the wood show through. Frankly, in my experience, the benefit is negligible. I like a satin finish, and use satin for all of the coats. The results are beautiful.

-- No matter how much you push the envelope, it'll still be stationery.

View Jon Anderson's profile

Jon Anderson

31 posts in 2166 days


#4 posted 01-23-2017 04:32 AM

Well I’m two coats into this , so maybe I’ll find out the old fashion way. I’ll let you know. Thanks folks.

-- jbander

View woodbutcherbynight's profile

woodbutcherbynight

3638 posts in 2243 days


#5 posted 01-23-2017 05:57 AM

I routinely use semi for the 1st coat over raw wood and if a gloss is desired do all other coats in gloss. Never tried satin as I do not use poly for that type of look.

-- Live to tell the stories, they sound better that way.

View ric53's profile

ric53

192 posts in 1354 days


#6 posted 01-23-2017 11:33 PM

I agree with Rich. I do all my build up with satin. The only time I deviate is when Im dealing with a highly figured wood that I really want to pop. Then I will use hi gloss for the build up and top coat with satin.

-- Ric, Mazomanie

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