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Author Topic: MDF  (Read 8692 times)

hopeitfloats

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MDF
« on: June 18, 2011, 11:20:10 AM »

 i have a large sheet of 5mm MDF and was wondering if it would be suitable for decking my ship if it was sealed and painted
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DickyD

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Re: MDF
« Reply #1 on: June 18, 2011, 11:26:36 AM »

Persoally mate as an ex carpenter and joiner with emphysema I wouldn't touch it with a barge pole.

Just my opinion  :-))
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Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk

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Re: MDF
« Reply #2 on: June 18, 2011, 12:03:12 PM »

All dust, wood, metal, plastic is a potential health risk, wear a mask when cutting or sanding it.

Make sure you seal it very thorughly though- the slightest bit of water and it blows out and goes all furry.

david j

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Re: MDF
« Reply #3 on: June 18, 2011, 12:32:24 PM »

hi, seal it well with resin i have used it a lot, so far no problems after 5 years of sailing my boats.
its the same as using card seal well with resin used this lots of times
thats my opinion :-))
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hopeitfloats

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Re: MDF
« Reply #4 on: June 18, 2011, 12:47:53 PM »

thank you all for that.  we are supposed to be getting a cold, wet  sunday so might be a good chance to try it out.
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Roadrunner

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Re: MDF
« Reply #5 on: June 18, 2011, 01:20:08 PM »

Watch for weight..mdf is not light even at 5mm

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Watchleader

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Re: MDF
« Reply #6 on: June 18, 2011, 05:04:10 PM »

IF.... {:-{ you are going to use it for decking, donít forget you will have to seal the underside as well as the exposed topside.
This is going to be tricky ensuring that all surfaces are sealed.  O0
Even if you turn the whole thing upside down and flow resin on, there will probably be deck supports that will stop good, even, coverage and drainage of excess resin.  :o

The best use for that large sheet would be to use it as a support for your modelling plans/instructions etc.
Thatís how I put mine to good use.  :-))

John
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HS93 (RIP)

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Re: MDF
« Reply #7 on: June 18, 2011, 07:02:24 PM »

cut off a small piece of the mdf and drop it in water for an hour seal it if you want first, then look at it a few days , you wont then use it on a boat.

Peter
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Netleyned

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Re: MDF
« Reply #8 on: June 18, 2011, 07:12:51 PM »

Do you have to take it out after an hour and then leave it for a few days?
If it has been completely coated with resin no way water can penetrate?

Ned
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John W E

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Re: MDF
« Reply #9 on: June 18, 2011, 08:18:36 PM »

hi ya there

If you seal it with polyester resin you are wasting your time.   Polyester resin isnt waterproof as after a few days of submerging in water it will begin to absorb and break down.  That is why we have a gel coat on the outside of 'lifesized and model' boats to create a barrier.   

Epoxy resin is water proof though, but, if you are going to go to the expense of coating MDF with epoxy you may as well spend your money on a good quality Birch ply.

aye

john
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Netleyned

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Re: MDF
« Reply #10 on: June 18, 2011, 08:30:59 PM »

Was Epoxy I was talking about having used West Systems on 1:1 vessels
All our 18mm ply was coated both sides before use and the edges sealed
after cutting to shape.
Polyester? Na Na

Ned
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RaaArtyGunner

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Re: MDF
« Reply #11 on: June 18, 2011, 10:35:31 PM »

Persoally mate as an ex carpenter and joiner with emphysema I wouldn't touch it with a barge pole.

Just my opinion  :-))

 :-)) :-)) :-))
The nice way to describe it is, that it is a more refined version of the cheap rough cardbord back on writing pads.
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Roadrunner

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Re: MDF
« Reply #12 on: June 18, 2011, 10:42:33 PM »

MDF is cheap rough cardbord back on writing pads only one good use for it make a stand for the boat!

That better ?   %% {-) {-) O0 ;D %) ok2 :-))  :P
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Peter Fitness

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Re: MDF
« Reply #13 on: June 18, 2011, 11:52:29 PM »

I know some people have successfully used MDF in model boat applications but, like DickyD, I wouldn't even consider it. Sure you can seal it, but even the slightest scratch through the seal will allow water to enter, with disastrous results.

However, as Dave Milbourn is fond of saying, suit yourself.

Peter.
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HS93 (RIP)

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Re: MDF
« Reply #14 on: June 18, 2011, 11:54:14 PM »

Do you have to take it out after an hour and then leave it for a few days?
If it has been completely coated with resin no way water can penetrate?

Ned

if you read the first post you will see that no where is epoxy of west system etc mentioned , he says PAINT

Peter
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yorkiej

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Re: MDF
« Reply #15 on: June 19, 2011, 12:54:49 AM »

i have a large sheet of 5mm MDF and was wondering if it would be suitable for decking my ship if it was sealed and painted
Quote:-   'if you read the first post you will see that no where is epoxy of west system etc mentioned , he says PAINT'.

Having read the first post, I see it says 'SEALED AND PAINTED'.  This, realistically, is not sealed with paint, but sealed and afterwards painted!!!!!!!!!!!!!!!!!!

Please read and digest before posting. It saves all the spurious posts like this one. (This means MY POST). ;D ;D O0 O0 :police:

Yorkiej
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HS93 (RIP)

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Re: MDF
« Reply #16 on: June 19, 2011, 01:30:56 AM »

yes but where does  it say west system or epoxy when you seal before painting it is normally sanding seal,


 and sarcasm does not help, bet you feel really clever now ?

Peter

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derekwarner

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Re: MDF
« Reply #17 on: June 19, 2011, 04:45:44 AM »

Guys....I agree with most comments

MDF =  :-)) material for bookends
MDF =  :-)) for compressive strength
MDF =  >:-o for sanding contours
MDF =  <*< for water resistance
MDF = no strength for insertion.....screwing into %%  %%

I agree with an earlier post..........MDF would make a good plan board  :D ...............Derek
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RaaArtyGunner

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Re: MDF
« Reply #18 on: June 19, 2011, 09:14:23 AM »

Quote:-   'if you read the first post you will see that no where is epoxy of west system etc mentioned , he says PAINT'.

Having read the first post, I see it says 'SEALED AND PAINTED'.  This, realistically, is not sealed with paint, but sealed and afterwards painted!!!!!!!!!!!!!!!!!!

Please read and digest before posting. It saves all the spurious posts like this one. (This means MY POST). ;D ;D O0 O0 :police:

Yorkiej
Without laboring the point all material should be sealed prior to painting.
This means to apply a sealing coat of paint prior to appplying the top coat AKA finishing or colour coat.
Sealers as mentioned can also be sanding sealers.
The function of a sealer, which is a different formula to the top coats, is to literally  seal the surface and facilitate the application of successive coats of paint.

MDF, sealed and painted is unsuitable for a deck.
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colin

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Re: MDF
« Reply #19 on: June 19, 2011, 10:05:42 AM »

Due to weight i would not use MDF in any form in construction of the model other than the stand due to it working like a sponge when near water. However it is possible to buy Moisture Resistant MDF but note the word resistant and not waterproof which i take as a manufacturer does not recommend where water contact may be possible

Regards
Colin
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Re: MDF
« Reply #20 on: June 19, 2011, 10:35:45 AM »

MDF is quite good for pattern making- lack of grain can be an advantage, and a couple of coats of primer to seal the surface gives a finish like plastic, but considerably easier to work.

nhp651

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Re: MDF
« Reply #21 on: June 19, 2011, 10:56:29 AM »

why do all posts of help on this forum have to degenerate into a personal argument.

after all, it's not a contest for the best answer from  "grumpy old men" it's supposed to be a forum where advice and help can be offered, NOT  a game of point scoring. <:( <:( <:( <:( <:(

advice has been given from all sides...now let the original poster make up his own mind from those personal opinions instead of arguing about what you've said......the forum AND  the world would be a lot happier place for it.

neil.
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Circlip

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Re: MDF
« Reply #22 on: June 19, 2011, 11:18:53 AM »

All materials have their own limitations and quirks. If the Elfins had their way, we'd all be wrapped in cotton wool, just don't let Nitric acid anywhere near it, it becomes Gun cotton - Explosive.

  Don't use 'Styrene or ABS for construction as that generates toxic smoke if burned and perhaps we shouldn't use PVC insulated wires for the same reason? Cyano adhesives, Epoxy resins?

  Whatever happened to common sense?

  Use whatever you want but research its limitations and take precautions against damaging yourself. %)

  Regards  Ian.
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hopeitfloats

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Re: MDF
« Reply #23 on: June 19, 2011, 11:20:54 AM »

hi guys. weather forecast was wrong so i didnt get anything done today ( house maintainence instead). i was planning to seal top and bottom with several coats of sanding sealer followed by paint. weight of MDF wont be a problem as i have already cut a piece for the deck but not shaped it and its actually not that heavy.  i have been working on the theory that seeing as its decking i would hope that it will stay relatively dry. i have got epoxy resin so  maybe a coat of that may be better than sanding sealer. might just try a small sample piece and see how it holds up to splashing. i have plenty to carry on with in the mean time.
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Colin Bishop

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Re: MDF
« Reply #24 on: June 19, 2011, 12:07:11 PM »

I think the real danger is as pointed out by Watchleader earlier - moisture getting into the underside from the air if the underdeck sealing is not perfect. Once there is a route in the moisture will slowly wick into the MDF and cause it to expand.

My feeling is that if you are making a model then the small quanities of material involved mean that it is best to use the most appropriate material and do the job properly.

Colin
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