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[portside II]

Thought i would have a go at a plig and build a tug hull and maybe stretch it for a barge hull.
so it was chesil in hand and a lump of timber (wagon trailer chock) and a form was made .

this was sanded smooth and given several coats of spray filler paint ,i also made a keel piece that fitted along the center.


as a trial i made up some resin and experimented on the hull to see if the g/f would release ,but it dont  :'( .
so can someone out there help me with a solution for an easy way of coating the hull to allow me to remove the g/f hull from the mould .
I have thought of cling film or maybe vasseline to cover the plug but not sure if there would be any adverse reaction .
daz

[Bradley]

Daz,
What you need is a proper release agent which you can obtain from any of the grp/resin suppliers.  I would suggest a search on Google for 'GRP resin' and I am sure it will come up with several.  Looks like you plug will need a lot more work - the plug has got to be perfect or your master mould will show every imperfection.
Good luck with you efforts.
Derek.

[Stavros]

Firstly you need to fill all the voids in the hull to obtain a smooth finish.Get in contact with Glassplies in southport and they will supply you with all the matterials by mail; order



Stavros

[Bradley]

I must be getting slow in my old age - it took me a night's sleep to realise that this is probably a spoof.  I think you would have been better using a well seasoned piece of LNER sleeper for your plug, several large pieces of chewing gum as filler and, probably, some KY jelly as a release agent.  Happy modelling.     

[John W E]

hi there all

One method I have used for a release agent in an emergency whilst working for a particular employer.  We had to take a cast using, believe it or not, a mixture of Plaster or Paris and Sand'n cement - when it had hardened, I lined the casting I had taken with Cling-film from my sandwiches at lunchtime  and the fibre glass moulding did release from this easily.

food for thought.

At least I ate my sandwiches before I used the cling film.
aye
john e

bluebird

[portside II]

Thanks lads ,
Derek, no it is not a spoof as i have not done moulding before this is my first attempt
Dave , yes you would be right that the plug would have to be sanded smooth as the lumps and voids would show on the finished hull ,but as this is the inner plug and i intend to make the outside as smooth as i can when applying the g/f and then sand it to the desired finish .
Don't forget the end product is of a well used dock tug and not a exhibit piece , so any dints etc on the hull would add charactor  .
John , thankyou for the info using cling-film i had thought of this but was not sure if the g/f would react .Did you use the inside of the cling-film and what were the sandwiches, this may be important as you might have stumbled on an alternative release agent  .
daz

[Bradley]

Hi again Daz,
My apologies about the spoof bit.  However you do need a good timber to make your plug and the experts use a hardwood that is easy to carve but I cannot remember the name of it and the only alternative that I can think of would be a plank on frame.  Really, I suppose, you could make your plug out of anything as long as it could be painted/varnished and polished and withstand the making of the #1 mould.  In fact some plugs are actually broken out of the first mould and, obviously, never need to be used again.  I would strongly advise you to get a proper release agent as your master mould is the most important one.  Don't go down the route of second best for your plug, make the best you can as all subsequent hulls will depend on it.  I know that Dave Metcalfe of Metcalfe Mouldings would tell you the name of the specific timber - you could get his email address and phone number from his website.  I think that the best filler is a car body filler (P38?) which is easy to apply and sand.
Happy moulding and I hope you are successful.   

[portside II]

Cheers Derek, like i said i am not sure exactly what i need to do ,but if i can make the wooden plug (is it called a plug if the finished hull is made on the outside) and apply something to ensure it can be taken out from the g/f hull when set that would be great .
I did think of vac forming but i think the plug is too big and its convincing someone with a vac former to let me ust their machine.
daz

[John W E]

Hi there PortsideII

When we used the clingfilm at the place where I worked; it was basically an emergency repair job on a machine casting - and it was 'as rough as a badger's tongue' - and to keep the machine going at all costs until the week-end.   Hey me sarnies were cheese 'n onion  and that is another story - never tell your wife what you like in sandwiches or you get the same every day!!!  - like the time she left the cellophane wrapper on the cheese slice - or the paper between the meat 

Anyway, to get back on a serious note; Obviously the advice in the above postings given to you is exactly right.

The more perfect your plug is, the better the mould will be when it is taken off.   First of all we have to try and understand which way you are going to go - there are several methods (as we all know) of producing a fibre glass hull.   One of them, which I believe you intend to do, is to create the shape of the hull that you require from some material.  Place a release agent over the top of this and then fibre glass.

Smooth the outside of the fibre glass down; and give this an exterior finish.  This is in fact a 'one off' plug mould which, if you are only going to build one hull is the correct way to go.   

If you wish to go the other method; and produce a fibre glass mould, which in turn produces a fibre glass hull.  To me, it is entirely up to yourself, but, this method has no real advantage over the first method apart from the fact that a) you can produce numerous hulls of exactly the same quality and shape and b) you can produce a hull of constant lamination thickness.

As far as making the plug is concerned, some of the professional  pattern makers/mould makers use a timber called 'Jelutong' to produce a solid plug/or a semi solid plug.   This material is very light and straight grained and it is easy to work with, as it doesnt split easily when forming complicated shapes.  Also, it can be sanded to a very smooth finish.   It is also very stable, in that it does not distort very much.

I suspect that this material may be a little on the expensive side, to use on a 'one off' plug.  Personally, I would produce either a plank on frame plug or a foam plug, using one of the high density foams.

One of the main problems people encounter is that when they try to cheat on making a plug; I have known several folk build a plug - plank on frame - but, they have left rather large gaps between the planks and filled these large gaps in with either a polyfiller/wood filler or P38 - this can work to a degree, but, what happens:

when we begin to laminate or apply the resin and matting; we have to be careful how we lay the matting up.  This is due to the fact that during the process of laminating there is a natural heat generated for curing and this build-up of heat, depending on the amount of layers applied can become quite excessive.   If you have an uneven thickness of your plug, some of the heat is dispersed in the thin areas quickly and held in the thick areas.  Consequently, sometimes the releasant can deteriorate and either melt or begin to break down.

This is where we end up with a situation where the lamination adheres to the plug; and we end up using either a chissel or a knife to break the plug away from the mould.  Consequently, it can sometimes do damage to your moulding.   To be honest with you, I have only heard or seen this where the person doing the laminating has been inexperienced and tried to build up too many laminates in one go, also, when they have had more resin left, they have just poured it over the top of the laminating - not realising the damage being done.

The other thing to bear in mind, when constructing a plug, it must be strong enough to withstand rolling with a roller of fair pressure, for removal of air pockets and also stippling with a brush.

Hope this rubbish is of some help to you 

aye
John e
bluebird

[Bradley]

Hi again Daz,
I think that John (Bluebird) has answered your queries very efficiently and the wood he mentions is the one I could not remember the name of.  If you intend using your plug to make a one-off hull then it does not need to have a perfect finish and I have read in the past of making a plug out of foam and then dissolving it out when finished but I think that you have to be careful with foam and resins as you may end up dissolving when you didn't want to.  I don't think there is anything else I can add except to possibly have a look in your local library or amazon.co.uk for books on GRP laminating.  Hope this helps.
Derek.   

[tigertiger]

I am not sure what is happening here.

Portside I am not sure I understand you process.

Are you trying to use the piece of wood as a male mould from which to lift you moulding?  Or as a plug from which to make the female mould and then to use this to make your hull moulding?

Either way, without a smooth surface the FG and resin will tind to fill the cavities and bind, especially around your keel area.

[portside II]

Thats right TT i can see what you mean  about the resin getting into the gap around the keel ,thats now why i will try the climg-film method (with a smidgen of cheese and onion essence as an extra) and then the resin hopefully wont get into that area . If all is well the two ply pieces can be removed and the keel which is in three pieces can be removed and then the sides taken out . This should leave me with a hull where i can fit bulkheads and smooth the inside with some more resin to add strength .
I will keep you all informed when i get a new batch of resin and matting .
daz

[John W E]

Portside II hi ya there

I have always found - Red Leicester with a smidgen of very strong la French onion on string  thee ones that make yer eyes watter for three days or more; they are the best - it adds that flavour to the moulding  along with the cling film that has just been removed the toilet seat - go on you know you have seen that and done that - where they stretch the cling film over the toilet and put the seat down - don't tell me you haven't don't that to someone!! 

hahaha

On a serious note though;

I can see where you are coming from now and you are going to use the plug that you have photographs of.  What you must do first though is fill and seal the end grain; if you do not do that, when you cover the hull with the cling film, it will go into the voids of the end grain - when you apply the resin, and, it will be extremely difficult to remove the casting from your plug.

So, you must fill that in with some P38 filler and sand it smooth.  Where you have the gaps along the keel, what you can use is plasticine - make sure it is the old type of plasticine - and not the new stuff that is sold which is similar to Playdoh as this reacts to any resin.   The old plasticine does not react at all.

You could use Polyfiller as this will break easily; when you come to remove your keel centre sections.  The only other thing is - what you could do - after you have finished sanding your plug and managed to get it nice and smooth - you could give it a coating of beeswax.   The hard variety of beeswax that the woodworking lads use for polishing is the best - the high temperature range.  This would give you the 'belt n braces' approach where if the clingfilm breaks down or splits; you know you have a bit of a backup behind it.

There's a bit more rubbish for ya to think on. ::)

aye
John e
bluebird

[Bradley]

Daz,
An excellent book on fibreglassing is The Fibreglass Handbook by RH Warring - a name that a lot of modellers will recognise.  It was published by Nexus Special Interests but, having had a look on Amazon, it does not appear, at present to be available.  It may well be that it is out of print and your local library might be the best bet.  It is only a paperback and I got my copy some time ago when I think it may have been on offer from Nexus.  Hope you are successful as it is worth getting hold of.
Derek.
(Talking about cheese - there is only one 'proper' cheese and that's Wensleydale - ask Wallace & Grommit).

[John W E]

Aye....forgot about Wensleydale Cheese - aye that was a grand day out wasnt it and crackin toast there Grommit - so I am not the only one who has the Wallace and Grommit DVDs watch out for the penguin 

there is a fibre glassing company which has been mentioned   Glasplies Fibreglass Products
 
Glasplies Fibreglass Supplies, 2 Crowland Street, Southport, PR9 7RZ
Tel 01704 540626 | Fax 01704 537322 | Email [email protected]

They used to do several brochures; which explained to the pure novice all of the mysteries of working with fibre glass, ranging from working out quantities of fibre glass materials to applying them, building moulds - topics too numerous to mention.    The brochures used to arrive in a thick envelope and there would be over about 100 pages all free from this Company.   I am unsure if they still do do this, as it has been a while since I was in contact them.

Well worth a look anyway and telephone call.

aye
john e
bluebird

[portside II]

You guys never fail to surprise me ,it dont matter what subject question is asked there is allways a positive and helpfull answer .
I now am enlightened in the basic art of g/f .
Derek ,i will look for that book at the local ,should be helpfull.
John what can i say apart from been a master (in my eyes) builder  you are ready to share your knowledge among the less fortunate of us (me),an e-mail has been sent to glasplies for their brochures  :)  :)  :) .
daz

[Bryan Young]

Daz,
What you need is a proper release agent which you can obtain from any of the grp/resin suppliers.  I would suggest a search on Google for 'GRP resin' and I am sure it will come up with several.  Looks like you plug will need a lot more work - the plug has got to be perfect or your master mould will show every imperfection.
Good luck with you efforts.
Derek.

One of the reasons I "plate" the hulls of old-time models is to give me an acceptable finish without all the hard labour. Kill 2 birds with one stone, so to speak. Cheers. BY.

[portside II]

Yes i can see what you meen B Y ,and from looking at your models the results speak for them selvs but as this one will be a male form and not a female form then any mouldings or marks and imperfections on the plug will be on the inside of the f/g hull .
Like i said if all goes well then the plug will be cut in half and extended to make a barge mould .
If it does then i may concider grp sheeting for the sides for strength as i can get this quiet easily as off cuts .
daz   

[portside II]

Me now a happy bunny , just got back from bridge town (Hull) with a supply of 5ltr resin ,catylist , chopped strand matting and heavy tissue as well as a big bag of off cuts thrown in for free .All that for £17. and a few pence .
So when i get chance to get into the shed i can make a start , i also recieved some advice on release agents and using wax which is just what you lads mentioned ,now where are those latex gloves.
daz

[Bryan Young]

Yes i can see what you meen B Y ,and from looking at your models the results speak for them selvs but as this one will be a male form and not a female form then any mouldings or marks and imperfections on the plug will be on the inside of the f/g hull .
Like i said if all goes well then the plug will be cut in half and extended to make a barge mould .
If it does then i may concider grp sheeting for the sides for strength as i can get this quiet easily as off cuts .
daz   

I still think you are doing this the wrong way around..could be wrong.

[John W E]

Hi there Daz

I hope I have caught you before you have disappeared into your workshop with Marigold Gloves on hands  :)  ready for the attack.

You are doing it the best way; you are going to have a bit of an experiment; and, if it all goes wrong we are only left with a large lump of fibre glassed wood  ::) I think it is better than having to chisel the plug out of the mould; leaving traces of cardboard shell plating in the mould  :-\ 

then only to spend another 2-3 days correcting your mould.

....

here then - a few thoughts for you:

fibre glass matting; generally speaking it does not like to be worked into tight radius' and corners - the larger the radius the easier it is  to lay the matting into the corner - and remember the finer the matting (in other words one ounce matting - in weight - will break down and work into corners a lot easier than one and a half - two ounces in weight) so, in other words the radius where your keel joins the bottom of your hull on the flat section, the corner try and keep this radius as large as possible:

edge where the bottom meets the side of the hulls; keep this radius as large as possible, what tends to happen here, if it is a tight radius, you get air trapped underneath the matting on the corner and no matter how hard you work it, it tends to try and lift the matting so you have a bubble:

If you cannot avoid having tight radius' for your first layer of matting, try and arrange it so it butt joints on the corner - in other words you have one flat piece of matting to cover the bottom of the hull, but it does not overlap onto the side - and the same for the side -one flat piece that butts up to the corner.

Consequently the next layer of matting you put on, overlaps, because this radius is increased with having the first layer of mattng on it.   It will ,you will find, be a lot easier to work out any trapped air.

Apply your resin first:  then apply your matting over the top of the resin and work your resin through the matting preferablt with a 'fluted or an open wire' roller.

When you first have rolled the resin through the matting, leave it for 2-3 minutes to allow the bonding that holds the fibre glass matting together to dissolve.   This allows you to work the matting a lot easier but, be careful, if you work it too much you will begin to introduce air into the matting which you want to avoid.

Whilst on resin; try and use an 'unpigmented / or clear resin' for the majority of your build up.  The reason being - it is a lot easier to see trapped air in clear resin than it is pigmented resin.

Not wanting to overload too much - but last & not least - although fibre glass is supposed to be a wonderful material, one of its major downfalls is it does not like large flat panels.   I know this wont really affect us in the model boat industry but, there are things that we can taken from the full-size industry and use to our advantage.

When you have completed this hull, and you are quite happy with it and have done what you want with it and now you are thinking about extending the hull, if it has any large flat areas on the sides or on the bottom; we must begin to think about introducting 'knuckles' on the outside of the hull shape; doing this will build in strength without increasing the thickness.   If you go further into building we can explain further what we mean about this.

The other thing, whilst we are talking about adding strength to a hull, do not always be fooled with the idea that adding extra layers of matting & resin to a hull doubles and trebles the strength of the hull and in some cases it can work against us when we have built a hull too thick.

Just as a guide you should be looking at 2 layers of one ounce matting and 1 layer of one and a half ounce matting.  Then, over the top of this, a layer of tissue matt.   Over the top of the tissue matt when it has dried, 2 coats of resin.

Any strengthening can be done on the inside of the hull when you remove the plug and sand the inside of the hull; the simplest method is to superglue a run of string down the keel (the type of string I am thinking of is parcel string) and over the top of this 2 layers of one ounce matting.   This will produce a ridge down the bottom and if you put 2 down the sides from bow to stern the same way, you will see how it increases the strength of the side of the hull and the bottom; without adding all of those extra layers.

If you wish; & you think you need to add ballast, instead of using string down the centre of your hull on the keel line; you could actually use the electrician electrical conduit pipe - the plastic variety which is about 3/4 inch diameter.  Glass over the top of this, and, then drill a hole in the centre and you can insert lead shot - the full length of the hull.   When you have sufficient lead shot in the pipe to ballast the model; you could then mix up some resin, pour it through the hole to stop the lead shot moving about.

Hope this has not given ya a head-ache  :-\   food for thought my friend.

Do not let anyone put you off - nobody learns if they do not try.

Only worry if your mould has cost you 100,000 quid and you then have to chisel the plug out of the mould - then a lot of questions to be answered 


aye
john e
bluebird

[portside II]

Right ,i have started on the hull .The first job was to nick a candle from the house ,the only one i could find was one of those scented ones ,at least it will take the smell of resin away. And the hull was given a liberal rub down with wax (cheap release agent)and assembly of the plug.
As i had a large amount of off cuts i decided to use them first and after laying them on the waxed hull i gave them a good stippling with resin.
The result was a fiberglass hull moulded on a wood plug (will it come out??).
After a night in the shed left to dry (the plug not me )the moment of truth had arived ,would my cheapways work



A bit of persuasion fith the screwdrivers and a kettle of hot water and the plug and hull parted






So the next job is on the inside ,motor, shafts, bulkheads etc .
more to come
daz

[hopeitfloats]

floor/furniture polish (the type with wax in it) works well and it has the added advantage of leaving the casting with a nice smell.

[TCC]

floor/furniture polish (the type with wax in it) works well and it has the added advantage of leaving the casting with a nice smell.

Ditto this... when I bought my gear from 'Glasplies' (southport) I found a tin of floor (furniture) wax... I said to they guy at the counter, I'm fibreglassing, not saving the wife from her chores!

For the guy casting cement, when I cast plaster, I use lard! The proper casting shop plasterers use tallow over a shellack sealer. Though cling film is a true mechanical barrier that you know will release the cast from the mould. 

For the OP, next time give a thought for 'strike offs', these are flat edges to the top of your mould that are perpendicular (90°) to the mould wall... the idea is that gives you a flat surface from which to level the top edge to your cast. It'll also gives some strength to that edge and keep it in shape. But you'll learn by your mistakes.. and you're next mould will be better again.

... and if I was you, I'd use a lot of release agent in that mould or you'll not get the cast out of it... fill all the imperfections and edges with it... fill anything that could feasibly catch hold of the resin. In fact, you may have been better making that mould in 2 halves and bolting them together with wingnuts. That's a very deep mould to retrieve a fibre-glass cast out of.

Good luck!