Help with Painting MDF

[MikeL]

Hi,

I've just spent the past 2 weekends building a nested toy box out of MDF for SWMBO'ette. It was my first project,(hence only using MDF) and I spent a great deal of time ensuring joints were correct etc. Unfinished, it looked a treat, I was quite chuffed with it. I sanded with 120, sealed with White Knight MDF primer. Another quick sand to denib, and then first coat. I'm using Gloss Acrylic (as the color choice I had, wasn't avialble in enamel..???.

I let the unit dry overnight, sanded with 400, and then the top coat.

Then the dissappointment set in, The finish is rather shoddy. Its certainly not something that i'm proud of. I have quite good paiting skills, but this one has let me down.

Should I have used a low nap roller, or was brushing the best option. I still have the individual boxes that sit inside the unit to paint, and I dont want them finshing the same. :(

[echnidna]

Sand it wet with W & D paper and refinish it with enamel.

[MikeL]

Thks Bob....


What about the unpainted boxes.. Perservere with brush, or use a roller..?

[Kev Y.]

if you are using acrylic paint, I would go with the roller. People tend to over brush acrylic paint, giving a "stringy" look to the finish.

[MikeL]

Cheers Kev,

I'll give the roller a try and let you know how I get on... :)

[Shannon]

G'day Mike,

Sorry for the late buy in, but was just passing and wondered how you got on?

I have also built an MDF toy unit for the 2 1/2 yr old SWMBO and painted it up. I used a roller as much as I could and brush for joints/corners etc. Found that the roller gave a more even spread overall.

If you can wait for enamel paint for the rest I would as it seems to a bit more durable. Also, I would suggest putting an extra coat on than normal if you have the time and patience, as mine is looking a little second hand after only 6 months of use (abuse!?!) I will be taking it out the shed soon to give it a couple of extra coats

Cheers
Shannon.

[john dd]

I am confused regarding which primer to use for MDF.
the following web site www.strategicdata.co.nz/spectel.doc/BESTW/bestwaa/htm (http://www.strategicdata.co.nz/spectel.doc/BESTW/bestwaa/htm)

which is part of Carter Holt Harvey manufacturer of Customwood MDF says "where smoothness is important apply a solvent/turps -based undercoat but do not thin the first coat..Water based undetrcoats will cause surface roughening which will require additional sanding"

Now the "White Knight web site 'use acqylic base undercoat as oil based will cause the surface to rough up ...or similar

Both give basically the opposite advice.

Any tip on which to use??

[john dd]

http://www.whiteknightpaints.com.au/s04_handy_hints/hints2.html

The link to the white knight site recommending acrylic is as above

[Kev Y.]

John dd, white knight look like they are refering to particle board, not MDF.. particle board will "fur" up as the moisture in the paint is soaked into the fibres, much like timber does when first varnished.

I am from the "old school" of painting, where you were taught to go with a set paint regime. if the finish is to be acrylic, use an acrylic primer/undercoat, if you as finishing in enamel, use and enamel (oil ) based primer/undercoat.

I know paint technology has progressed in the past 25 years, but surely you can not too far wrong.

with either paint system you WILL get some raising of the fibres on the surface. The trick is to not oversand and leave scratch marks on the surface.

[turbo]

i agree with brudda

start with one product and finish with one product

though nowadays it is very common to undercoat/seal with a polyurethane , and then you can get away with spraying almost anything over the top of it.