Painting MDF

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@barb and I are helping girl scouts make some fun laser cutouts with MDF and the plan is to spray paint them and let the kids continue with their artistic visions.

Only issue is that last year I tried making that wichita flag puzzle for maker fair and zomg spray painting that dark brown MDF was miserable, the paint just soaked right in with no discernible affect on the color for like the first ten coats or something. Maybe I eventually primed it or used house paint but now I don’t remember. But I do remember when we were doing that firetruck we had a similar issue, and did we use glue as a surface primer? @David was that your wisdom? I was going to email you, figured others could benefit, or maybe somebody else has found a nice way to prep it.

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Cardboard is that way too.

source - made a cardboard chair that drank $80 of spraypaint (and then got a B+).

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You can make a mixture of half water/half white glue. Mix it up in a bowl or paint tray, then brush it on and let it dry. One coat should be enough to seal the surface for painting.

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You may think cardboard and MDF take a a lot of paint, but have you ever tried to paint a red carpet blue?

@whyameye :wink:

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that’s it? next time we get a good pile of empty boxes (we’ve been unpacking) I’m making another cardboard chair!

or rather, start a cardboard chair, get sidetracked, and then have half a cardboard chair in my basement for the next ten years.

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When we did the fire truck, the idea was to keep the paint from attacking the styrene foam. One layer was enough to keep them from interacting. I haven’t tried it on cardboard, but it should work the same. The water spreads out the glue enough to make a thin but complete layer. When it dries, the water is gone, but the glue is left behind to make that barrier.

And I believe that the hardboard we cut on the laser is HDF, not MDF.

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