finishing mdf for outside use

[cd]

This probably seems like a stupid idea but I'm considering making a turned birdhouse from mdf.
Main reasons being I wanted to try out a couple of idea's without using anything expensive and had some mdf lying around. The basic idea will be a segmented barrel type body (the mdf bit) with a turned top and bottom. So question what should I finish the mdf with to protect it ? My initilal thoughts would be to seal with some sanding sealer then spray with car spray paints starting with a primer then undercoats and several top coats. but any idea's would be appreciated.

cd

 

[Anonymous]

cd
I'd go for the moisture resistant mdf ...probably pick up some offcuts at a local joinery :?:

 

[Gill]

If the rain stops tomorrow, I'll take a photo of something I made out of standard MDF two years ago and treated to a couple of coats of acrylic primer, followed by sprayed gloss paint and finished with a car lacquer. You won't thank me for posting the photo - it isn't pretty after being exposed to the elements .

Gill

 

[Gill]

The rain stopped. Briefly. So here's the example of what happens to MDF treated as I described above after being exposed to the elements for just under a couple of years:

That is mould around the top of the sign, the 'e' inserts have vanished, and the sign is generally discoloured. Hence the need for a replacement sign as I described in my workshop thread. However, I've gone a bit overboard in terms of weather-proofing the new sign . I thought I'd apply a top coat of yacht varnish over the white gloss paint and it's gone blotchy - what a disaster! I'm not proud, so here's the evidence:

I'll now have to wait until the varnish has cured to the point that I can sand it off and re-spray with white gloss paint. Ah well, at least I've learned another technique that doesn't work; I certainly know a lot (with apologies to Edison).

Gill

 

[Alf]

Gill, that's not blotchy. That's marbled. People pay extra for that! [-X

Cheers, Alf

 

[Gill]

Gill, that's not blotchy. That's marbled. People pay extra for that!

:lol: (hammer) :lol:

Hey, now there's a thought :idea: :!:

KerrrrCHING!!!

Gill

 

[cd]

Thanks going to the trouble of posting the pic Gill,
my design will minimize the exposure somewhat I'm intending on a bowl shape something like this.

this will be the mdf bit
and a top (probably teak)
like this

to cover it
with no sharp edges or places for the water to gather I'm hoping the mdf will hold up
But I'm only guessing since I havn't done this before and at the moment I've only got as far as glueing the 12 staves togther for the body

cd
(who's found a 3d drawing package for turners )Here if you interested