help for mdf

[tinatina]

Hello all,

I'm working a heavy-duty shelving unit made of MDF and have gotten to the finishing stage. As far as I can tell my two options are 1) varnish, sand, varnish, or 2) acrylic base coat, sand, acrylic paint.

In terms of MDF, which of these would you recommend ?

I would like to point out that I am in France, where there is apparently no such thing as an MDF-specific primer, and where MDF is rarely used in general. BTW, just out of curiosity is MDF primer useful/necessary for any kind of finish (water or oil-based) ?

Ideally I'd like to finish the shelves in white, though not a bright shiny enamel white. I suppose I could go with the natural varnished MDF color if necessary. My impression is that tinted varnish wouldn't work so well on MDF, an argument in favor of acrylic ?

Also, should I sand before applying anything, or just in between coats ? By hand or with a sander ?

If I go with varnish, I assume this needs no primer of any sort ?

I've read a lot about the infamous MDF edges absorbing lots of paint - no real solution to this, other than to coat it more ? Drywall joint compound was suggested, but it's true this could crack

Thanks for your wise advice.

 

[petewood]

I'm working a heavy-duty shelving unit made of MDF and have gotten to the finishing stage. As far as I can tell my two options are 1) varnish, sand, varnish, or 2) acrylic base coat, sand, acrylic paint.

In terms of MDF, which of these would you recommend ?

Either of these methods would work on mdf

I would like to point out that I am in France

,

That's ok, no need to apologise.

where there is apparently no such thing as an MDF-specific primer, and where MDF is rarely used in general. BTW, just out of curiosity is MDF primer useful/necessary for any kind of finish (water or oil-based) ?

I have used ordinary basecoats and primers and they have worked fine for me.

Ideally I'd like to finish the shelves in white, though not a bright shiny enamel white. I suppose I could go with the natural varnished MDF color if necessary. My impression is that tinted varnish wouldn't work so well on MDF, an argument in favor of acrylic ?

I think I would use acrylic in this case, the colours seem a bit denser than a tinted varnish, especially for white. It may not be so hard-wearing though.

Also, should I sand before applying anything, or just in between coats ? By hand or with a sander ?

This is the important bit! If you have a sander then sand the cut edges until they are smooth, then give a quick sanding by hand between coats

If I go with varnish, I assume this needs no primer of any sort ?

Try thinning the varnish a bit for the first coat.

I've read a lot about the infamous MDF edges absorbing lots of paint - no real solution to this, other than to coat it more ? Drywall joint compound was suggested, but it's true this could crack

The finer the edges are sanded the less paint they will absorb. If you can machine sand them down to 240 grit they will not absorb much more than the faces. Don't know about drywall stuff, never used it.

Thanks for your wise advice.

Might not be wise, it may be rubbish.

 

[Jasonb]

I make quite a bit of MDF fitted furniture and my usual method of painting is :

1 ct acrylic primmer/undercoat sand lightly with 180grit silicon carbide particularly the edges.

Second coat of the acrylic primer/undercoat lightly rubbed down with 320 grit.

then two coats of oil based eggshell with a very light sanding between coats.

All applied with a 4" foam roller on the flat surfaces.

All the painted stuff in this album was done as above.

http://photobucket.com/albums/v156/jasonballamy/Fitted Furniture/

As were this and all the units and woodwork inthis kitchen

Jason

 

[Zampa]

Im not too keen on water based primers on MDF they can cause the grainy surface to riase up...and osme of the fibles are difficult to remove by sanding....thus giving a slight wood chip effect.

 

[Jasonb]

Agree with that especially if its cheap MDF from the sheds, I build all my furniture from Moisture resistant MDF and get very few raised surface fibres.

Jason