Help! The edges of the Mdf trim are not sealing, they soak in the paint and continue to be very rough. I know FH the magazine had a blurb on this but I cant find it. Any ideas? Jeffysan
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One of the tips I've often heard, but never had occasion to try is sealing the cut edges with some thinned down drywall compound...
HTH
Paul
paint on yellow glue..
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Seal them with a 50:50 sizing mix of yellow glue and water. It will take 2-3 applications, but the edges will seal. Sand gently after 24 hours for a smooth edge.
Thin down some glue and paint it on. Hit it with sand paper before painting and you'll be good to go.
Doug
mdf primer anyone?
I use a bunch of MDF for custom closet shelves and fire place mantles. Typically if I want a real clean edge I use lightweight spackle compound. Rub it in the edge, let it dry and sand it down.
On closet shelves I use a mix of yellow glue and water. Usually about half water and half glue. Brush it on, wipe up the excess and let it dry. Then sand it down. The finish is good, but not as nice as the light weight spackle.
I then usually use a good primer (Zin 1-2-3) and it seals up nice and takes a great top coat.
Have fun
Sand to 150. Sanding sealer. Sand 180. Sanding sealer. Prime. Sand. Paint.
A mixture of glue and water is applied to the edges of mdf. It is called 'glue sizing'.View Image
When you say they "continue to be very rough"....by that, what do you mean? - you have sanded/filled and sanded them and they are still rough?
or you are painting the rough edges wondering where all the paint is going, and why your edgeds are still rough?
I saw a blurb in FW about using diluted drywall paste... However I not long ago I custom cut hundreds of feet of MDF to trim out my whole house...all I did was clamp the boards together and gang sanded them with 150 grit on my RO sander.... no problems and no paste either.
personally I don't see the need to paste the edges, you have to let it dry and you still have to sand it...skip the paste and grab the sander I say.
EDIT: also when ripping MDF use a high quality blade such as "Frued Glueline" which leaves a smoother cut than the factory edge.
Edited 9/1/2006 1:34 am ET by alrightythen