# Prefinished Plywood



## themitrejoint (Mar 9, 2011)

I am ready to start my next project using pre-finished maple ply wood. I don't know what the pre finish medium is. Does anyone know what it is and will it take a water based primer and finish coat?


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## rhett (May 11, 2008)

I know that the Columbia purebond is an aluminum oxide based conversion varnish. Finish compatibility is a mute point since the finish is so hard. I have successfully applied Sherwin Williams waterbased kemaqua lacquer primer and color overtop with no issues. You must make sure to sand the finish enough to give the surface a nice tooth though.


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## Sawkerf (Dec 31, 2009)

I doubt if I would spend the extra money for prefinished ply if I were painting it. Sanding, priming, and painting unfinished ply eliminates the sanding needed to get the paint to stick, so why bother? - lol


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## DLCW (Feb 18, 2011)

Dido on Sawkerf's response. I would not spend the extra money on the PF ply. I would get a good quality birch or maple ply and perform the finishing operations you want. I think you will be much happier with the results.

I use PF American maple ply on all my cabinets boxes as the plywood itself is excellent quality and the finish is really durable. On end cabinets, the panel that is exposed is the same material as the faceframe (oak ply for oak faceframes, cherry for cherry, etc.) I prefinish these (color and conversion varnish) end panels after the CNC cuts them out then assemble them just like they were one of the PF maple ply parts.

To find out what the finish is, you will need to contact the manufacturer or the lumber yard where you got the PF ply from. They should be able to find out for you.


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## rhett (May 11, 2008)

When buying PF ply I pay the extra $5 a sheet for the 2S ply. On a paint grade cabinets the 2S ply keeps me from having to finish the inside and the painted surface is as smooth as glass. The time taken to stop and finish one side of a sheet is less than the cost to just buy a finished sheet, plus the painted finish is smoother than spray over raw wood. On clear coats I follow Don's method.


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## John1 (Aug 3, 2008)

As others have said, sand the prefinished surface well before priming. I use Zinzer BIN. You can also get prefinished one side and then you don't have any worries about going over the prefinished surface with paint, although I have done that many times with very good success.


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## themitrejoint (Mar 9, 2011)

First - thanks for the responses. I did some experimenting. As rhett and John suggested, I sanded the surface with 120 and got a good "tooth". I applied the finish coat without priming. Got the best result of 3 different processes, 1. primer w/ shellac, 2. primer w/o shellac, 3. finish coat, no primer.

I always apply two finish coats with light sanding between so I am saving the priming step and I don't have to finish the interior. Also, as rhett said the finish comes out glass smooth with no grain show. The quality of the finish is well worth the extra few bucks for the pre finished.

Have to agree with DLCW, the ply itself is excellent quality with a supper durable finish.

The only downside I have come across is that glue doesn't bond to the finish.


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