Are there any tricks to prepping/painting the cut edges of MDF? It seems like no matter how smooth a routed or sanded edge is before painting it always seems to look and feel a bit rough or “fuzzy” after the final finish coat is applied. Is there some trick, e.g. using an oil based primer so the fibers don’t swell as much, sanding after priming and repriming again before topcoating, etc. to make the edges perfectly smooth? I’ve been using a good quality latex primer followed up by two coats of latex semigloss – no sanding between coats but there has to be some trick that I’m missing.
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SC
Brush/rub on/smoosh around-Titebond I,II, or III. Let dry-sand lightly-apply finish coats.
And maybe take time between coats-your constant waterbourne unless plenty dry-probably fuzzes up the edge.
The glue has worked for me.
I suspect you need to apply some sort of water-resistant layer -- shellac, a shellac-based primer like Kilz, a "pre-stain" sealer, or an alkyd primer.
agree with calvin
I used to use Bartley's Pore Filler on milled MDF profiles. Paint it on thin, let it dry, then lightly sand. It gave a glass-smooth surface that painted up just like the skin on the face of the sheet of MDF.
Lately I've been using Titebond like Calvin.
I try to use an oil primer too. You can use a latex, but you'll get slightly better results with oil. Or alkyd. Call it what you wish.
Drywall mud and primers
Thanks for the info guys. I've done some more research and some people seem to have success with smearing on a very thin layer of drywall mud on the edges and sanding. The use of a solvent based primer also makes sense.
Another question: I always apply two coats of primer if my topcoat is white or a light color. Any thoughts on using an oil for the first coat followed up with a second coat of water based primer? Good idea, bad idea?