Matte Medium

I used diluted matte medium to attach ground foam. It dried white in many places. Most noticeably where it ran onto rocks, but also under the ground foam in many places. First, is there an easy way to fix this now that it's dried. 2nd, is this normal? It hasn't been excessively humid. It's in the house, so the temperature variation is minimal. I diluted it at something like 5 parts water to one part medium, maybe thinner. Any help is appreciated.

Paul

 

Strange. I've used it for years, and never once had that happen. Is it possible that something on the layout surface bled into the solution? Anything painted white in the vicinity of the ground foam that you glued down?

 

That's kinda thin. I usually dilute mine 2:1 water to MM.

 

No, nothing white in the vicinity that should be able to bleed. Hydrocal rocks painted/stained with acrylic paints. The foam is glued to tan grout.

I try to keep it as thin as I can get away with. Mainly to avoid problems like this. It seemed to work in the past with white glue. The ground foam is definitely firmly attached.

 

This is unusual. Try diluting it with distilled water rather than tap water. If it still comes out white, switch to a different brand of matte medium.

 

I've never had it turn white either. If I am using diluted matte medium to bond ballast I tint it with some craft paint. It bonds just fine and doesn't turn white. And I use distilled water and not tap water to dilute it since we have hard water. That might be the difference.

 

Hum, maybe the Matte Medium brought something out of the grout? That's the only thing I can think of. What kind of ground foam are you using?

I've also used diluted Matte Medium for attaching ground foam with no issues, but that was over painted plaster or painted wood.