Car body spray on MDF?

[fatmarley]

Do you think a coat or two of Rustins clear MDF sealer on the joints would be good idea before using the Morrells primer/sealer?

 

[sploo]

Do you think a coat or two of Rustins clear MDF sealer on the joints would be good idea before using the Morrells primer/sealer?

If Morrells specify that their sealer goes on the MDF first then no (there's also the issue of compatibility - mixing products from different systems can cause problems as one can react with another).

That said, I don't know the Morrells products, and it might be that Rustins works really well, but it appears to be water based; which never strikes me as a good idea for MDF.

A case in point (of mixing systems); don't try to seal MDF using polyurethane varnish then paint with 2k urethane... that was one of my many experiments with getting a good finish. And it wasn't a good one.

 

[mailee]

The Morrells sealer is a single pack very much like sanding sealer but thicker. It has rapid drying and sinks into the upper fibres of the MDF making them 'hard' once dry about half an hour later it can be sanded to a smooth finish ready for the primer. HTH. :wink: Oh almost forgot, if you use the 2k wet look urethane it is very, very hard to wet flat and polish after it has been left for a day or two so be prepared for plenty of elbow grease to get a high gloss finish. Brilliant stuff though, hard as nails.

 

[fatmarley]

Ok, thanks guys. I wont use the Rustins primer then.



Stupid question time - Where's the best place to buy Morrells paint? Can I buy it online? Or should I go to the nearest shop (Bristol IIRC)?

 

[studioman]

If I'm going to paint MDF I usually use a spray primer filler (now often called a hi-build primer) in tins, which often comes in grey, or mucky yellow colour. It is thicker than the ordinary primers and builds up well. As regards MDF edges, I just use a bit of wood filler and sand it down, THEN apply hi-build primer, resand, then apply to the whole panel. Undoubtedly you have to go back over some parts but it works eventually.

 

[Graham Orm]

Had a look at the paint doctor website and he said the best way of sealing an MDF edge is to fill it and then sand. I wonder if some wet rot wood hardener would stop the edge from fluffing up?

By working down through grits to about 1500 wet and dry I've sanded MDF edge to a glass like finish, much smoother than the flat surface.