Waterproofing MDF board.

[conny]

I've been tasked by my boss to come up with a solution to waterproof a piece of MDF board, 600 x 400mm
It is to be placed outside mounted on a post with a sign on it. My suggestion, (bit tongue in cheek), was to suggest dipping it in a tray of hot molten wax and allowing it to drip dry. He didn't go for it. LOL

Does anyone know if/how it can be realistically done?

 

[Burnerman]

The worst possible choice for exterior use.....do choose something else - anything else!
John

 

[lostinthelight]

If it wasnt critical Id have a go with yacht varnish thinned with cellulose thinner but it was discussed here
https://www.diynot.com/diy/threads/how-to-waterproof-mdf.41155/

 

[conny]

The worst possible choice for exterior use.....do choose something else - anything else!
John

I've said that to him. Suggested we should by some marine ply, say 9mm minimum thickness, and we would have a better chance of it lasting. At the moment he is looking for a quick, cheap solution which is going to cost more in the long run.

 

[conny]

If it wasnt critical Id have a go with yacht varnish thinned with cellulose thinner but it was discussed here
https://www.diynot.com/diy/threads/how-to-waterproof-mdf.41155/

Think I'm just going to have to convince him it's a non-starter. He's a paper pusher type with limited diy knowledge so it may be a bit of a battle.
He'll see I was right eventually.

 

[foxhole]

PVC board , any timber will fail eventually in weather .

 

[Notch7]

Think I'm just going to have to convince him it's a non-starter. He's a paper pusher type with limited diy knowledge so it may be a bit of a battle.
He'll see I was right eventually.

If it's important, for £25+ delivery you can buy a 600mm x 600mm 12mm tricoya mdf

That'll last for many years outside.....upto 50

https://www.atlantictimber.co.uk/TM...d-CYuoEyL2_WqmCJ1jfX35Pag2ZMbd_RoCJqgQAvD_BwE

 

[big-all]

perspex/acrylic sheet and plastic stick on letters or symbols
different colours /luminosity available
wooden frame if required to support the edges

 

[conny]

perspex/acrylic sheet and plastic stick on letters or symbols
different colours /luminosity available
wooden frame if required to support the edges

It's a plastic 'Assembly Point' sign that he wants to stick to it. I suggested getting 2 pieces of mild steel from a local engineering company and giving them a few coats of paint but he wants to use whatever we have lying around. To prove my point over the MDF I'll leave a small piece out in the rain over the next day or two and then take it in to show him what happens. He's a good boss in many ways but sometimes won't listen to the voice of experience.

 

[Burnerman]

Maybe you have something like Correx plastic kicking around, or perhaps a scrap of polycarbonate roofing?
You’ll spend ages preparing and painting other materials!
John

 

[lostinthelight]

why not make a batten frame the same size and fix to that

 

[Boxster1]

Just tell him the MDF will be ok after a couple of coats of Tartan Paint!

 

[Deleted member 174758]

Think I'm just going to have to convince him it's a non-starter. He's a paper pusher type with limited diy knowledge so it may be a bit of a battle.

You can say that again, although the word I'd use is far harsher. You'd be far better off getting a piece of Foamalux or the like from a sign writers (or Amari plastics) - plastic, weatherproof, relatively cheap and maintenance free. And it won't rot, unlike wood products

 

[johnny2007]

Vacuum pack the mdf.
Your local butcher can help.

 

[diy_fun_uk]

It's a plastic 'Assembly Point' sign that he wants to stick to it. I suggested getting 2 pieces of mild steel from a local engineering company and giving them a few coats of paint but he wants to use whatever we have lying around. To prove my point over the MDF I'll leave a small piece out in the rain over the next day or two and then take it in to show him what happens. He's a good boss in many ways but sometimes won't listen to the voice of experience.

Yes but maybe not thinking straight. If he calculated the extra time it'll take you to faff about trying to find a solution for the existing piece of mdf, plus the cost of any additional stuff you need to buy to make it more suitable, he'd quickly realise it makes more sense to bite the bullet and buy an alternative solution instead. Most of the solutions suggested above hardly break the bank.