View Full Version : MDF Finishing Question

The Wizard
10-31-2004, 04:43 PM
Hi Folks,

I am building an engraver/router (project log here..... http://cnczone.com/forums/showthread.php?t=6244&page=1&pp=5 ) and should start cutting the MDF parts tomorrow :banana: . Seeing as I live in Canada and we suffer from dampness in spring/fall and high humidity in summer I will obviously need to finish the MDF in some way (and fairly quickly) once the parts are finished.

What are you guys using/recommending for MDF finishing? I have searched the forums and seen several different options including sanding sealer, varnish, oil paints, latex paints and automotive spray paints.

Is there a definitive answer or is it a case of using whatever is to hand?

Does latex paint cause any problems with swelling/warpage on application with it being water based? If it is OK to use which is better gloss, flat or semi gloss? I am leaning towards gloss or semi gloss as it should make cleaning the machine easier (but I could be wrong ;) ).

I have a space problem here that means that I may be forced to use the kitchen to paint the parts if I cannot do it outside due to weather constraints (temperature, rain etc.) The kitchen has a natural gas space heater (with open flames at the bottom) within 4 ft of my working area so volatile substances like oil paints and varnish are not really suitable for indoor use in my case (I don't want to go BOOM from a build up of fumes :eek: ) . Spray paints could be used outside as they dry quickly and can be brought indoors after spraying.

Does anyone have any suggestions/tips/opinions?


10-31-2004, 06:13 PM
No definitive answer really, but...
Shellac primer, seals the wood, dries quickly...really quickly, so fast that the place you started will be ready for the final coat before you are finished priming the entire unit.
Any final coats you want...latex house paint is fine as is any other paint. Semi and gloss give an easier to clean finish as you said.
Shellac is thinned with alcohol but you can go ahead and use the uncleaned primer brush to apply the latex final if the brush is not allowed to dry (wrap it in a plastic bag and put it in the fridge if there is any time between priming and applying the first ‘final' coat.) The latex paint will dissolve the shellac in the brush as you paint and then it will just be water clean-up. Yes the first few strokes of latex will have primer mixed in the color, but dealing with that is easier (and safer) than cleaning the brush with alcohol.
Apply the primer OUTSIDE away from ignition source. :)

10-31-2004, 07:22 PM
Use semigloss latex paint. Grey looks best. MDF paints up very nicely and gives the illusion your machine is made of 3/4" boiler plate steel. :)


The Wizard
10-31-2004, 11:29 PM
Thanks for the replies guys. Latex semi-gloss it is with the possible addition of a shellac primer depending on local availability.