# 2 or 3 Coats of Polyurethane for poplar?



## TheShaver (May 9, 2010)

I have just completed my shaving stand for my brushes and razors. Made out of poplar, wood clue and water based rosewood stain. I will keep this stand in the bathroom which will of course be high humidity part of the time. I plan on applying a Minwax polyurethane semi gloss. Should I apply 2 coats or 3 coats? Would a 3rd coat have any effect?


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## Colt W. Knight (Nov 29, 2009)

I generally put a lot of coats of poly when I finish something. If you use a sanding sealer. 2-3 costs would work just find. Without it, I think you'll need more. Just put coats in until your satiisfied with the look and. Coverage. Everyone applies and thins differently, so its hard to say what youbshould do.


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## TheShaver (May 9, 2010)

Colt W. Knight said:


> I generally put a lot of coats of poly when I finish something. If you use a sanding sealer. 2-3 costs would work just find. Without it, I think you'll need more. Just put coats in until your satiisfied with the look and. Coverage. Everyone applies and thins differently, so its hard to say what youbshould do.


What is a sanding sealer?


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## phinds (Mar 25, 2009)

A sanding sealer is dewaxed shellac or various other finishing agents that are used to (1) raise and stiffen the grain of wood, particularly any loose fibers, before sanding, and sometimes (2) to act as a "barrier coat" that allows for a more even coating by the regular finishing agent, some of which will be absorbed irregularly by some woods if you don't have a barrier coat and some of which won't stick well to particular woods (poly for example really sucks at sticking to cocobolo).

As to how many, it depends a lot on two things. (1) what kind of wood are you talking about, true poplar (cottonwood) or what many lumber yards sell as poplar (which is actually American tulipwood and is also called yellow poplar). Cottonwood is one of the most absorbent woods around and will need more coats than yellow poplar. (2) Are you slathering on thick coats or wiping on thin coats. 


I wipe thin coats on my bowls and generally use 10 coats after 2 layers of dewaxed shellac as a sanding sealer / barrier coat, but with the shellac I could probably get away with maybe 4 thin coats of poly. I use a lot more because I need the extra UV protection (I use spar poly) for the exotic woods I use and also because I use VERY thin coats to completely avoid air bubbles. You don't need that many for either kind of poplar unless you happen to have a green-tinted yellow poplar and want to keep it from turning brown.

For "what is a sanding sealer" or similar questions, see:

www.hobbithouseinc.com\personal\woodpics\_glossary.htm

Paul


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## cabinetman (Jul 5, 2007)

A sanding sealer performs a few functions. The intention isn't to raise the grain, but that can be a result. It's primary function is to apply a base coating for the finish. Some sealers are easier to sand, so they call them sanding sealers.

In your particular case, your final finish (oil base poly) can be thinned 50% for a couple of coats as a sealer, which will allow for good penetration into the wood. Being reduced, it sands easily. You then can use the finish at your thinned ratios for wiping (or brushing if you prefer).

This method uses your final finish as a sealer and base coat, which IMO, is a more durable base coating than shellac.


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## phinds (Mar 25, 2009)

cabinetman said:


> A sanding sealer performs a few functions. The intention isn't to raise the grain, but that can be a result. It's primary function is to apply a base coating for the finish. Some sealers are easier to sand, so they call them sanding sealers.


Son of a gun, guess I had that one wrong ... I learn something new here every day ... thanks for that clarification.

It's my understanding that shellac is, as you say, not very durable itself, but as a barrier coat under a more durable finish, would that really matter?

Paul


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## Colt W. Knight (Nov 29, 2009)

I typically wipe my piecs down with alcohol to raise the grain, then sand the grain raised lightly to achieve a smoother finish. I always use a sealer. I simply get better results when I do.


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