Im going to build in the near future a theater cabinet for my components and 2 sub boxes. I would like to make them black. I would like to know what is the best method of painting MDF board. I would like to know how to prep it, what primer and paint to buy, how many layers of each to put on, and what to sand with between each step. I would like flat black or something with a little shine, nothing glossy. Also, if someone could recommend a good spray gun I could get from home depot or lowes that would be great. Finally, would I put a sealer overtop of the paint?
Thanks, Joe
If you don't want to see any evidence of the joints and the edges (which absorb paint much more than the faces), seal the MDF with something that will form a barrier to future paint. Shellac, lacquer, polyester resin and primer will work but you want to fill the edges and any other holes or gaps in as few coats as possible, preferably drying as fast as possible. Whatever is used, it will need to be sanded flat afterward. Once the edges and surfaces have been sealed and sanded, automotive primer is a good choice because it covers well and drys fast. Any primer will need to be sanded, too. Once that has dried completely, you can wipe mineral spirits or Naptha on it to look for imperfections.
The sheen you described looks like you want Satin, which isn't really shiny but isn't as dull as flat. Some paint companies offer "low sheen" paints and this is automotive, too. One use for this kind is GM air cleaners on older cars so if you know what that looks like, you may decide that it's what you want.
Another way to get this look is by using melamine laminate. If you have a router with a decent edge trimming bit, you can do this pretty easily and it would take a lot less time than painting. Most big box stores like Home Depot sell laminate and contact cement. I use small diameter foam paint rollers to apply the cement, let it become tacky, stick it on, use a J-roller to make good contact and wait a while. Trim it flush, clean up the edges with a good fine mill file and with a little practice, it's not too hard. If you want an edge that acts as an accent, you can use a rabbeting bit and then glue whatever material you want into it. Wood, composites, solid surface material, etc would all work for this.
As far as a gun for spraying, if you have a compressor (the larger the tank, the better), Harbor Freight has a sale on gravity feed guns on now. I have one of the high pressure guns and two of the HVLP conversion guns. These use a regular compressor but are a compromise between the true HVLP guns, which work by pumping high volume, low pressure air and one of the main results is much less overspray. I shot my kitchen cabinets with Minwax semi-gloss polyurethane using the conversion gun and they turned out really well. All guns will produce overspray but it's much less when the gun has been adjusted correctly.
