problem with my mdf, any opinions???

[chippymart]

Hi guys, new to site and my first post and could do with some opinions on some dodgy sheets of MDF i got the other day.
Had 20 odd sheets of different sizes turn up and stuck a coat of acrylic primer on both faces straight away to seal as I always do as for painted cabinets I am building. Was a nice sunny day so dried nice and quick. Had 4 sheets of 6mm and now dry, resemble shreded wheat. All the others I painted,12mm,18mm, and 25mm sheets finished as expected. Can only think that where I got them from (Alsford timber merchants in the south) that the moisture got into them at their yard affecting the face. Got the manager coming to have a look as I cant seem to lose the fibrey look. Given them 3 coats of undercoat now but fibres still showing through in a nice embossed look.Any opinions would be kindly recieved. Had 180 sheets off them on my last job, all for cabinet work and not ever come across anything this bad. :?

 

[jasonB]

Its likely the 6mm is from a different source and just basic contract grade MDF. I don't touch the stuff prefering to use MR (moisture resistant) MDF for all my work from a known maker such as Medite or Caber. Far denser with a harder surface and the cut or machined edges don't fluf up.

J

 

[EssexChris]

Hi,
I would agree with JasonB, we work with lots of MDF. It can vary greatly Medite is great but, occasionally we get the odd sheet from B & Q sometimes the 6mm they stock once primed is just as you described, have you attempted to route any of it, the 6mm from B & Q wont hold any detail or a hard edge when machined, its almost unworkable.

Chris.

 

[chippymart]

Hi Chris,

Luckily I'm not doing much with it, just making some shaker doors so only a small chamfer on it and using as backing to units. Just the finish on shaker doors is problem. Going to discard and prob get replaced with MR. Never had a problem with face finish before,whatever grade.
Must be a dodgy batch

cheers

 

[Bradshaw Joinery]

what was the surface like pre paint?

 

[mailee]

I had exactly the same problem recently. I had to source some 6mm MDF quickly and the timber merchants were closed. As I have to order in the 6 MRMDF It would have meant a couple of days wait for it. I got some from B&Q and sprayed a couple of coats of Morrells primer on and it was just as you describe 'shreddies' It took me four coats of primer sanding between with 320 to get it prepared! I shall not be using that again and will wait for the Medite in future.