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[RST]

Another "old fashioned" method is Paper-Mache".  I did experiment with this technique some years ago and the results were published in the May 2016 issue of the Model Boats magazine. It was also to see if some use could be made of all the junk mail which comes through the letterbox...!


Using the more porous newsprint type of paper and wallpaper adhesive, the inside of an old moulded plastic hull was coated with layers of paper that had been torn into smaller pieces and then soaked in adhesive.  Each layer was allowed to dry before the next layer was added.  A thickness of a couple of millimetres produced a surprisingly strong hull.  Some balsa strips had to be added around the edges of the hull, to add some stiffness and also give more area for the cardboard deck to be glued onto.


The outer surface of the hull was not as smooth as it ought to be and required some filler (from a tube of ready mixed Polyfiller).  The hull was sealed and waterproofed with a liberal application of some varnish left over from a domestic job and produced a surprisingly tough model.


After adding RC gear, a simple superstructure based on a small merchant vessel and a lick of paint, it was sailing around on a local water.  To be honest, it looked as good and performed as well as some models that have been made from "proper" materials.


Glynn Guest

Hi Glynn,

Am interested in your post of the cargo ship.  I've made paper mache things this way though no luck with wet boats, but I also learned how to lay up a GRP mould in the same way using PVA as the release agent.

...But I'm intrigued as you had the female mould to work from?  Presumably the black vac-forming?  I suppose this is tucked away in your arsenal but where did this come from in the first place please?  It looks an interesting base-hull to work from.  I'm guessing it was something ad-hoc or not available anymore?

Rich

[GG]

Rich,
       The black plastic mould used to make the "Paper-Mache" hull is old, 40+ years.  So, I have no idea where it came from.  Now residing in the garage rafters along with a Marblehead yacht hull of the same vintage....


The key to success with such "unsuitable" materials is to thoroughly soak it with something like varnish.  It both waterproofs Paper-Mache and adds much strength and stiffness, so much so that I had to jump on the hull before it could be put in the waste bin!


Glynn Guest

[tonyH]

As far as I remember CROID was the brown gunk made from dead animals

[Merpanda]

I too remember Croid. I think it was what is called a ‘cold’ hide glue. Available today under the ‘Old Brown Glue’ brand and others. Animal hoof and hide glue (basically collagen) is amazing stuff.  The ‘hot’ version is standard for musical instrument building because: 1 infinitely variable tack according to dilution. 2 Self-clamping -it actually pulls the joint together and any clamps are just to prevent lateral movement. 3. Can be melted by applying hot water to the joint allowing for dismantling for repairs. Unfortunately not waterproof or it would be great for boatbuilding . . ,


I also remember boatbuilding with cascamite and painting the joints with formic acid that set it off. Stingy fingers if you had any cuts or cracks! Good stuff for a close joint-line.


Glues are a bit of an obsession of mine, although my knowledge has got a bit dated of late. Very impressed by polyurethane glue for full size boatbuilding - fast setting and very strong in a close joint. Needs to be clamped hard though cause it foams!


Still impressed though with the effectiveness of balsa cement on wooden model boats. Have a number of old hulls assembled with nothing else and still solid. Not waterproof enough for full sized but more than adequate for painted and varnished models.

[Colin Bishop]

I also remember boatbuilding with cascamite and painting the joints with formic acid that set it off.

I think you are confusing Cascamite (add water) with Aerolite which used formic acid as a hardener.

Colin

[Merpanda]

Ah yes! Aerolite 306. I often wondered if crushing handfuls of ants on the joint would do if I ran out of acid . . .