Polyurethane over white paint - it's yellow

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Old 11-09-09, 05:57 PM
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Polyurethane over white paint - it's yellow

Hi,

[I'm posting this on a few of the forums.]

I just spent 3 days priming/painting a new Andersen Frenchwood patio door (lots of grilles!). I painted it white using a water based paint. I asked the guy at Home Depot about lacquer vs polyurethane vs varnish since the door instructions said to finish w/ one of them. The guy basically said one of them would turn yellow (can't recall which) and I said the door is white, and I don't want a yellow tint! Well he sends me home with something that turned yellow! It's an oil-based polyurethane (clear satin).

How can I fix this w/o ruining the paint?? Can I somehow get the poly off and then cover w/ something else (w/o having to do any repainting)?

Thanks!!!
 
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Old 11-09-09, 06:28 PM
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Oil based poly typically yellows.Only water based poly should be used if you want a clear finish that stays clear.I'm not sure there is a way to save the paint and remove the poly,really you need to remove it and start over.

Too bad you went to a big box where the help doesn't give proper advice...
 
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Old 11-10-09, 03:42 AM
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Oil base poly/varnish will always turn white paint yellow. I'm sure the door painting instructions also made allowances for paint. An oil primer with most any type of enamel should satisfy Anderson as far as warranty goes.

You can sand some or even all the poly off but you will have to repaint If you can sand 90% of the poly off it would be ok to recoat with your latex enamel [waterborne enamel would be better] otherwise you will need to coat the poly with a solvent based primer [you still need to scuff sand] or you could use an oil base enamel but white oil base enamels tend to yellow over time.
 
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Old 11-10-09, 06:43 AM
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Thanks for the replies!!

This is what the Andersen material says:

"When painting apply a primer to the natural wood. Let the primer dry overnight.
After the primer is dry apply an oil-base or water-base paint. Finish the wood with
a quality conventional lacquer, varnish or polyurethane."

And I even called Andersen and asked about the topcoat and the guy definitely suggested to do it.

So, to sand it off, what is the best way to do this? It has grilles which is the most painful part. Would I use 220 or start higher and finish with 220? It'll be hard to sand the grilles - what's the best way to do that....

And once sanded, will a single coat of paint be sufficient?

Thanks!
 
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Old 11-10-09, 08:18 AM
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You won't get far sanding with 220, I'd start with 120 and really anything 150 grit or above will be fine for applying a finish coat of paint.

Unless you can sand of most of the poly - you'll need to use a solvent based primer. On the grilles, IMO the best way to go would be to wipe them down with a liquid deglosser and then prime them. You can get zinnser's BIN in spray cans, so that might speed it up for you.

I think there was probably a lack of full communication when the finishing instructions were printed up. They should have said to paint; use primer, let dry and then a quality enamel, for natural or stain finish use lacquer, poly or varnish. I doubt the rep you talked to had any working knowledge about the finishing process.
 
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Old 11-10-09, 10:22 AM
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Thanks. In the Andersen doc, there was another para dealing with staining.

"• Let any stain dry overnight. After the stain is dry, finish the wood with a high-quality conventional lacquer, varnish or polyurethane."

What infuriates me is that I questioned myself whether I should even do the topcoat (not because of the yellowing), and I figured if they said to do it, I should do it.... ughhhhh
 
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Old 11-10-09, 01:35 PM
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If the manufacturer has a step by step instruction for finishing a product all relevent steps should be taken otherwise you can effect warranties etc as well as the life of the product and it's performance.It's not really Andersen's job to know every detail about all possible finish choices but those who sell the finishes should know how the products will perform and especially in light of the specific requirements you had you should have left that business with the right product.In your case this was not difficult or unusual and it speaks to the quality of help in big box stores and their training that information that should have been known by that help wasn't and therefore you were sold product that did not perform as you needed it to at least in part because it's the wrong product.
 
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Old 11-11-09, 09:29 PM
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I don't recall ever reading any window / door manufacture's finishing instructions stating to use a clear coat over an enameled or painted finish. I usually read their instructions too.

These are some "general guidelines" I found with a few minutes of internet searching for Anderson window/door painting and finishing. Perhaps the finishing instructions are different for your door. See PDF

You are not going to be able to sand off the urethane. You will need to prime with a good bonding primer, and repaint over the top.

Note: if you do any sanding, be very careful of the glass. Even the slightest "touch" with sandpaper will scratch the glass.
 
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