Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Working vessels R&D: => Topic started by: hopeitfloats on June 18, 2011, 11:20:10 am

Title: MDF
Post by: hopeitfloats 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
Title: Re: MDF
Post by: DickyD 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  :-))
Title: Re: MDF
Post by: Subculture 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.
Title: Re: MDF
Post by: david j 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 :-))
Title: Re: MDF
Post by: hopeitfloats 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.
Title: Re: MDF
Post by: Roadrunner on June 18, 2011, 01:20:08 pm
Watch for weight..mdf is not light even at 5mm

Title: Re: MDF
Post by: Watchleader 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
Title: Re: MDF
Post by: HS93 (RIP) 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
Title: Re: MDF
Post by: Netleyned 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
Title: Re: MDF
Post by: John W E 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
Title: Re: MDF
Post by: Netleyned 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
Title: Re: MDF
Post by: RaaArtyGunner 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.
Title: Re: MDF
Post by: Roadrunner 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
Title: Re: MDF
Post by: Peter Fitness 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.
Title: Re: MDF
Post by: HS93 (RIP) 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
Title: Re: MDF
Post by: yorkiej 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
Title: Re: MDF
Post by: HS93 (RIP) 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

Title: Re: MDF
Post by: derekwarner 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
Title: Re: MDF
Post by: RaaArtyGunner 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.
Title: Re: MDF
Post by: colin 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
Title: Re: MDF
Post by: Subculture 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.
Title: Re: MDF
Post by: nhp651 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.
Title: Re: MDF
Post by: Circlip 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.
Title: Re: MDF
Post by: hopeitfloats 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.
Title: Re: MDF
Post by: Colin Bishop 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
Title: Re: MDF
Post by: Martin [Admin] on June 19, 2011, 01:25:54 pm
My friend Pete built his Springer barge from MDF.
It was very well sealed in all aeras and had no problems with it until it was sailed on a very wet afternon and not dried off.
Next time he went to use it he found a partially assembled  MDF springer kit sitting on his work bench!i
.... it went back together OK once dried out and has had no problems since!
Title: Re: MDF
Post by: Peter Fitness on June 20, 2011, 12:03:11 am
why do all posts of help on this forum have to degenerate into a personal argument.

Neil, I don't see this thread as degenerating into an argument, but as people expressing their opinions based on experience. If the OP wishes to use MDF, then that's his prerogative, but he did ask for advice/opinions as to its suitability, and that was given. He may find that he has no problem with the material, in which case no harm will have been done.

Peter.
Title: Re: MDF
Post by: yorkiej on June 20, 2011, 01:16:42 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



At my advanced age and with my experience of materials and the command of the English Language, I am well qualified to pass comment on spurious comment.
I have used vast amounts of the relatively new medium of MDF in marine envionments at 12 inch to the foot sealed with a variety of sealants, not including epoxy of any North, East, South or West Systems, without complaint from the end user.
I take it that modelling in this medium is not much different from full size use and the end result should be the sameif properly done.
I did not intend to be sarcastic, merely to make a point, but if someone feels put out by this, I apologise, but the Yorkshire anology remains ' If the cap fits, wear it'.
As far as I am concerned, this post is now closed to my eyes.
John
Title: Re: MDF
Post by: HS93 (RIP) on June 20, 2011, 03:18:17 am
AH so you haven't used it on models ? well come back when you have also just because you have done this sort of thing since Noah was in his Arch does not mean that you are any good at it, yes I can be sarcastic as well.  %%

anyway my eyes are closed to this post also and ill scream if you put anything nasty  :D

Peter
who has also got 40 years experience with wood time served etc but does not mean I have a clue what I am talking about, but this is just a HOBBY where we or I build model boats .
Title: Re: MDF
Post by: Roadrunner on June 20, 2011, 09:00:08 am
LOL wow this topic went to pot in no time , started with some good advice and some light hearted humour too boot... ended well.. badly....  i need to join in  {-)

Quote
At my advanced age and with my experience of materials and the command of the English Language, I am well qualified to pass comment on spurious comment.

With age dose not always mean more wisdom, ( i was going to add a comment about being senile but thought to harsh this morning you were lucky!!)  {-)

Quote
I have used vast amounts of the relatively new medium of MDF in marine envionments at 12 inch to the foot sealed with a variety of sealants, not including epoxy of any North, East, South or West Systems, without complaint from the end user.

not yet.. but im sure when the boat sinks you'll soon know about it....

Quote
As far as I am concerned, this post is now closed to my eyes.

is another way of saying bla bla i'm not listening any more (close minded)

Quote
but the Yorkshire anology remains

I have a one as well... ''sometimes you can't teach an old dog new trick's''

I was trying to be Sarcastic, so if you can't take a joke not my problem.  Im sure Admin will delete the top bit anway  O0 :-))

I wouldn't use mdf on a model at all, weight, quality are all issues you cannot guarantee for a marine use without the need to seal it using resins, if you say use ronseal exterior wood preserver/sealer im going to slap you... mdf is so tightly compacted it cannot absorb the sealer deeply enough with out literally submerging the whole lot and leaving it for a few hours, by which time its starting to come apart, swell and distort once dried.

Mdf great for indoor use, flat pack furnituer, and boat stands, used on a boat as skinning material .. uff  taking a chance... LOL

And then it comes back to cost... to seal the mdf using epoxy you just added to the cost and weight, where as some one already pointed out you may as well buy some good quality ply and seal it the old fashioned way at less the cost & to better effect.

I use for many larger projects marine grade ply in either 2-3 or 4 mm thickness's pre treated, and ideal for the larger more bulky work where strength is also needed (bulkheads etc) I have used 8mm ply in my tug as hollow bulkheads, one for strength and the only to reduce how much extra ballast i put in when you have to load 30Lb of dead weight in then using some of the weight as reinforcement is not a bad idea, well i though so anyway.
Title: Re: MDF
Post by: John W E on June 20, 2011, 09:14:06 am
Well said HS93 - I have to view this topic with one eye closed and the other half open as I have had a lot of experience building full sized boats through family connections and we must have built well over 40 boats of varying sizes.   I used to work for the Company who were the first to import the West System from the U.S.A. The Gourgen Bros. and the first boat was on show at Earls Court in London and it was a small sailing dinghy Carvel built by McNulties and it sure wasn't built from MDF  %% IT WAS THOUGH made from TOP GRADE MAHOGANY costing an arm and a leg; even though the West System is a good system its first use was for gluing the planks together but the West System is an expensive system to use for modelling - but - as someone has already said suit yersel.....or if the cap fits wear it - as long as it isn't covered in a West System epoxy  %) %)

Mind you on a serious note we have to think about the other things such as gum paper and shellac (might have spelt that wrong)  cos a long time ago people used to build models using this method and they have stood the test of time.

aye
john e
bluebird


Title: Re: MDF
Post by: tugmad on June 22, 2011, 08:32:22 am
Hobbies do a kit called Plucky the tug and it is All M D F, my brother was given one and he sealed it with Finishing resin which is epoxy based  and has no trouble with it at all
Title: Re: MDF
Post by: nhp651 on June 22, 2011, 08:59:46 am
Neil, I don't see this thread as degenerating into an argument,
Peter.

eat your words peter, eat your words,  {-) {-) {-) {-) {-) %% %% %% %% %% %% %% %%
Title: Re: MDF
Post by: Peter Fitness on June 23, 2011, 12:35:06 am
eat your words peter, eat your words

Never Neil, it's just a lively discussion  %) {-)

Peter.
Title: Re: MDF
Post by: tugmad on June 23, 2011, 08:26:58 am
Here you are chaps to prove a point Brother Peters  slightly modified Plucky the M D F tug  the wheelhouse was replaced with a lighter one as she rolled even more than she does now. ok2 ok2 ok2
Title: Re: MDF
Post by: tweety777 on June 23, 2011, 09:06:11 am
why do all posts of help on this forum have to degenerate into a personal argument.

Because personal arguments work best to explain why someone should do it your way.
Besides, it's also easier to adopt a certain advice when the person who gave the advice explains why he/she did it that way so you can adjast the advice a little to suit your project.
I think giving personal arguments is only a bad thing when it's used to make the other person feel less good.

Greetings Josse
Title: Re: MDF
Post by: Nige52 on June 23, 2011, 09:14:10 am
Equipage, the company that make all those nice looking classic speedboats, plank on frame style, use MDF for all the bulkheads and battery trays, I have the Riva and also the Gold Coast, no problems at all so far  :-)

(http://smittieshobbies.tripod.com/pics/tanks/riviera.jpg)
Title: Re: MDF
Post by: Colin Bishop on June 23, 2011, 09:53:07 am
The posts on this subject seem to assume that MDF is MDF. In fact there are various grades and densities of the material including a moisture resistant type.

Some info here: http://www.ukworkshop.co.uk/forums/are-there-differant-quality-grades-of-mdf-t12256.html

So maybe everybody is right!

Colin
Title: Re: MDF
Post by: hopeitfloats on June 23, 2011, 11:36:11 am
as the OP i have been following this thread and are actually finding all the differing views very interesting :-))
                                                                  craig
Title: Re: MDF
Post by: RaaArtyGunner on June 23, 2011, 10:57:54 pm
Never Neil, it's just a lively discussion  %) {-)

Peter.

Our Pollies, and no doubt others, call it a Robust discussion, so we could also adopt that phrase.  {-) {-) {-) O0 O0 O0
Title: Re: MDF
Post by: Martin [Admin] on June 24, 2011, 08:27:38 am
Just read that, very interesting, good find Colin!   :-))


The posts on this subject seem to assume that MDF is MDF. In fact there are various grades and densities of the material including a moisture resistant type.

Some info here: http://www.ukworkshop.co.uk/forums/are-there-differant-quality-grades-of-mdf-t12256.html (http://www.ukworkshop.co.uk/forums/are-there-differant-quality-grades-of-mdf-t12256.html)

So maybe everybody is right!

Colin