"Sealer or primer needed for MDF buildings?" Topic

Ahoy; I've searched for this topic but nothing turned up for my search terms -- but I ran across a discussion recently someplace here about how those MDF laser-cut wood buildings required application of a sealant and/or primer before painting, or the paint would be absorbed to a degree into the porous wood. So you'd get "bleed" or staining or other unwanted effects, especially in applying washes.

Can those with experience in painting MDF terrain and buildings advise? I have a big stack of these but haven't started to paint any yet. I don't want to ruin this stuff by not knowing about any pitfalls. It's beyond my ordinary painting experience.

Recommendations for products sold in the US would be appreciated! I think I read about this issue in a British-based blog and the sealers mentioned were all UK products I can't find here in the States.

I think it would be best

Try Winsor & Newton acrylic Matt varnish, two coats, both sides, brush applied.

Paint with your normal paints.

W&N artist products are generally available worldwide.

I used a spray primer that I found at Home Depot that is amazing. One can did about 4 large 28mm scifi buildings. Let me search a bit and I can come up with a link.

Don't use anything water based if you can avoid it.

Gesso works reasonably well. Almost any of the better known brands would be OK as they differ very little in their basic constituents.

Not sure I'd use varnish of any sort as a sealer/undercoat.

Also I'd try painting your buildings with what you'd normally use on large terrain items, you may find it works OK.

MDF varies in absorbency so it is difficult to generalise but I've found it is more likely to reject water-based paints than absorb them (hence a wash technique may have problems). If that happens a light spray of the cheapest primer you can find should help.

Here is the spray enamel that I use:

link

MDF is wood. Why would there be a problem with a primer for wood?

I use good old basic spray on Rustoleum primer (black, gray, or white – depending).

Works great.

I use Sanding Sealer to close the grain of the MDF. Works wonders.

MDF is not "wood." It contains resin and wax, among other things.

MDF is typically made up of 82% wood fibre, 9% urea-formaldehyde resin glue, 8% water, and 1% paraffin wax. The density is typically between 500 and 1,000 kg/m3 (31 and 62 lb/cu ft).

I'm pretty sure there are deviations of this.

I use house paint to prime it.

I have been having great success in using contrast colors directly on the unsealed MDF. It also has been taking drybrushing well, too. I use acrylic paints exclusively.

In those areas where a space has a poor fit is a prime location to add a climbing vine. Simply apply glue in erratic lines and dust with flock. (I use Faller 170492 thin glue that has a built-in thin metal tube applicator for this as it gives easier control for where you want the vines.) Flowers can be added by simply dotting colors upon the dried flock vines or window box. (Adds some color to an otherwise drab looking house.)

There are a few links on YouTube, including one by Sarissa Precision on priming and painting their own products.

Great stuff, thanks for all the suggestions and tips!