MDF Primer + Varnish

[sarah_4_jamey]

I was woundering weather i can put mdf primer on to mdf boards that i have, leaving it to dry and puting a coat or more of yatch varnish ontop.

Dont really know if you can put varnish ontop of primer?

 

[JohnD]

why do you want to?

 

[sarah_4_jamey]

im building a viv thats why.

Been told i should just use 2-3 coats of yatch varnish on them yet some have said to use primer then varnish ontop

 

[snowdrift]

I've always put varnish straight on - mind you that's normally acrylic varnish. Can't honestly see what a primer's going to do that a coat of varnish won't.

 

[sarah_4_jamey]

am trying to make the mdf boards waterproof, so if i use varnish straight in would that make it waterproof or do i need to use someother things?

 

[JohnD]

varnish is a waterproof coating, but MDF is easily attacked by moisture.

Have you considered making it it out of WBP or marine Ply? these are both water resistant materials. marine ply has an attractive hardwood veneer and can look very good when varnished

Take extra care to protect the edges with your varnish.

Varnish is generally chosen to allow the beauty of the wood grain to show through, but MDF has no beauty and primer will obscure whtever the material is. If you want to use MDF, just paint it.

Moisture will penetrate through any screw holes.