painting mdf

[Eoin Ryans]

Hi

i want to make some letters from mdf for my baby nephews wall to spell out his name.
i plan to cut them out from 8x 4 sheet, 1/2" thick.

im pretty open to design, but will probably route the edges wit an ogee bit.

Would the best method be to print out a design and trace it to the mdf and then cut out the letters on my bandsaw.

The second part of my query is how to finish them.
ive seen recommendations on using zinsser bin primer but this is expensive here in ireland. will any solvent based paint be ok once the surface is sealed? for the routed edges i understand it is best to first seal with automotive filler?

Thanks

[John Schweikert]

Oil based primer seals MDF better than water based primer. Then paint with whatever your choice is.

[Charles Wiggins]

Would the best method be to print out a design and trace it to the mdf and then cut out the letters on my bandsaw.

In my rolls in both education and in my church I have always had access to overhead projectors, and lately data projectors. They make this sort of thing easy. Make some calls to schools and libraries. You might find one you can borrow, especially the overhead projectors. Here in the US a lot of schools have them sitting around collecting dust.

ive seen recommendations on using zinsser bin primer but this is expensive here in ireland. will any solvent based paint be ok once the surface is sealed? for the routed edges i understand it is best to first seal with automotive filler?

As far as the painting goes, no direct experience, but I had always heard that you can seal the edges with thinned wood glue. Found this: http://www.finewoodworking.com/how-t...nting-mdf.aspx

[Phil Thien]

As far as the painting goes, no direct experience, but I had always heard that you can seal the edges with thinned wood glue. Found this: http://www.finewoodworking.com/how-t...nting-mdf.aspx

Yep, this is what I do, it works great.

[Peter Aeschliman]

I like spackle for sealing the "end grain" of mdf. It's a whole lot less messy than thinned glue (aka "glue size"), and it sands much easier. I didn't think it would work well the first time I used it, but was pleasantly surprised.

Definitely do not use a water based primer. It will make the surface super rough. Oil based for sure. Once you seal it with oil based primer, you can use a compatible water based paint.

[Richard Coers]

Practice with painting one letter before doing the entire job. You may change your mind on the ogee bit. End grain MDF is a REAL job to paint well on the end grain. I've used spackle, and made my own glue size. Didn't care for either. If you sand too much on the spackle, you get raw MDF edges again. I don't use MDF anymore.

[Peter Kuhlman]

Shellac works great to seal and harden the MDF. Issue is the MDF may look very smooth but if painted with a gloss paint it will show any imperfections in the surface. Like was said above, drywall sparkle works well to seal and fill and seams, cut edges, flat surfaces. I sure would not put a fancy edge on the letters as will make it extremely difficult to sand smooth after applying any sealer or filler.

[Peter Aeschliman]

The key with spackle is to apply it really thinly with your fingers. Only very lightly sand it after that.

[Howard Rosenberg]

I'm with Peter Kuhlmann - shellac - vastly underrated - hugely versatile - Howard

[Roger Rayburn]

Yes to spackle (or thinned glue, they work equally well). Yes to shellac. Yes to lower gloss vs. higher gloss paint. No to doing a routed edge treatment. Yes to doing a complete letter through a complete process before doing the full project.

[Eoin Ryans]

Thanking guys- I'm beginning to think that i should use wood for this project. I see that poplar is said to be good for painting. Problem is that poplar isn't readily available here..

[Steve Milito]

Practice with painting one letter before doing the entire job. You may change your mind on the ogee bit. End grain MDF is a REAL job to paint well on the end grain. I've used spackle, and made my own glue size. Didn't care for either. If you sand too much on the spackle, you get raw MDF edges again. I don't use MDF anymore.

I built a couple of loudspeaker boxes with MDF. I've tried the glue size and shellac. The cut edge of MDF really soaks up whatever sealer you use. I've gotten acceptable results but was never really completely pleased with the results when painted, especially when going for a gloss finish.

[johnny means]

I've done miles of profiled MDF edges. IME glue sizing is the best tecnique. I use a 50/50 glue water mixture rolled on with a small foam roller. Coat, sand, coat, sand, coat, sand gives me results smooth enough for Italian lacquer and faux marble finishes. In fact, getting the faces as glossy as the profile becomes a problem. The glue size also toughens up the edge against spilts and chips. I recently did a job for a repeat customer whom I had done a Playset for about 8 years ago. I had used the sizing technique and after 8 years of hard play (the paint job showed that) not a single edge had a chip or split.

[John Schweikert]

IME glue sizing is the best tecnique. I use a 50/50 glue water mixture..

What is IME? Thanks.

[johnny means]

What is IME? Thanks.

In my experience