Making a simple shelf out of MDF that is 11"X24". Would like to give it a quick coat of latex paint that I have in my stock without giving it a coat of primer. The primer I have I think is also latex. Will the moisture from the latex paint affect the MDF? Thanks
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painting MDF
- Thread starter jim
- Start date
Short answer, yes the latex will affect the MDF. The very least you should do is coat the edges with Kilz. From what I’ve learned, water based paints will get into the pores and cause the MDF to swell, so you put an oil based primer on it to seal it, then paint it with whatever you want. I’ve done this many times and it works very well.
txvwnut
Well-known member
I've used straight latex primer and paint on MDF with no issues. The trick is to prime first then paint.
ncfireman1918
Well-known member
You can seal the edges with PVA glue (I use regular old Elmer's). Once dry, give it a light sand, then prime with Oil based primer. Kilz or Zinser oil based works really well. Once primed, finish with your choice of paint. You can sometimes get lucky, but at some point you will swell an edge if you just paint it with latex.
ALinCarolina
Well-known member
I prefer to hit MDF with some spray shellac before painting. Alcohol base and dries extremely fast and everything sticks to it
rlitman
Well-known member
I prefer to hit MDF with some spray shellac before painting. Alcohol base and dries extremely fast and everything sticks to it
Well, shellac is a strictly indoors undercoat, but then again, so is MDF. I like the idea.
If I were doing this right now (not that I would, as I generally leave MDF unpainted, and reserve my painting time for better materials), I'd probably use Kilz original oil based primer, just because it soaks in a little, hardening the surface more than shellac. I like Kilz on wood, because it does a pretty good job of sealing knots that latex primers **** on, and because I can work with it in the dead of winter in my frozen shop.
lostmind
Well-known member
I have MDF for walls in my basement bathroom. I used latex with self priming.
15 years , no problems
15 years , no problems
I have MDF for walls in my basement bathroom. I used latex with self priming.
15 years , no problems
You did the edges too?
lostmind
Well-known member
You did the edges too?
Only the exsposed edges
K'ledgeBldr
Well-known member
I would do the extra step for nothing more than knowing I won't have to make ANOTHER shelf.
It's that "measure twice, cut once" mentality!
It's that "measure twice, cut once" mentality!
ALinCarolina
Well-known member
Yes, I assume the shelf will be indoor. I also assume you want to use the MDF because you have it lying around. The oil based primer will work great too, just take a little longer to dry. No point in using latex primer if you are concerned about water absorption though. Most latex paints are so thick I guess that's why water absorption is generally not a big problem.
MDF also will sag with a lot of weight but at 24" you should be fine.
Here is a handy calculator for shelves:
https://www.woodbin.com/calcs/sagulator/
If you plan on putting heavy stuff on it you could also attached a solid wood strip to the front to stiffen it. That's also a handy way to cover plywood edges. I have used MDF for some small shelves too. The advantage of MDF is you can route a decorative edge on the front. The last MDF shelves I did were small corner shelves, essentially a quarter circle with routed front edge.
MDF also will sag with a lot of weight but at 24" you should be fine.
Here is a handy calculator for shelves:
https://www.woodbin.com/calcs/sagulator/
If you plan on putting heavy stuff on it you could also attached a solid wood strip to the front to stiffen it. That's also a handy way to cover plywood edges. I have used MDF for some small shelves too. The advantage of MDF is you can route a decorative edge on the front. The last MDF shelves I did were small corner shelves, essentially a quarter circle with routed front edge.
ncfireman1918
Well-known member
I prefer to hit MDF with some spray shellac before painting. Alcohol base and dries extremely fast and everything sticks to it
AL, good advice on the shellac. I’ll have to try that next time I work with MDF. It definitely would dry a lot faster than the PVA glue. I learn something new every time I’m on Garage Journal!