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I've tried a couple of paper and pulp approaches. Both have suffered from shrinkage issues. My latest attempt used stips of 1/16inch thick cardboard from postal mailing cartons. They were run through my paper shredder giving me 1/4 wide planks.
Using my mold (used for wooden models) and I planked the mold with cardboard planking glued together at the edges. Then I placed stips of paper from file folders accross the hull. Then I again planked the hull lenghtwise with 1/8 strips of the 1/16 card board.
I used a mix of 50/50 Titebond carpenter's wood glue and vinyl wallpaper paste.
So far it looks very good. However the cardboard is soft and dents. I want to add a few layers of PM to harden the surface. If I do it carefully I don't think the PM cause a shrinkage problem.
How is a nice smooth sandable surface achieved? Should I use paper toweling or tissue PM for the final layers?
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You could make your last layers with fine paper (e.g. tissue) and only PVA. Alternatively, you could use gesso. A friend gave me a recipe once which I have used successfully.
"Sprinkle 2 tablespoons of whiting into a container of water and allow it to settle. "DON'T STIR"! ..After it has stood for several minutes, carefully pour off all of the excess water.
Add one tablespoon of white glue and one tablespoon of Linseed oil (raw or boiled) and stir throughly.
The Mixture should have the consistency of thick cream. If it is too thin, sprinkle in more whiting and stir till smooth. "
You can use just a teaspoonful of Linseed oil but it would probably be less waterproof. Be careful where you dry it because the linseed oil can smell.
It can be smoothed with wet and dry sandpaper.
DavidO
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I tried making the last layers with tissue and only PVA.
As I tried to apply the tissue is simply broke apart and became a mess.
I then tried to make a tissue pulp. Took a roll of tisse in a large pot of water and beat for hours using my paint mixer. Which made a massive wet pulp. I am not sure just how fine the fibers should be, they seem to gell together.
I reached into the pot and took out handfulls of the wet pulp and put it into a small container. Squezzing the pulp against the sides got the mass mostly free of water. I then added PVA and mixed until there was a heavy pasty mass. There were no visible lumps. However when I tried to smooth the pulp-paste onto the PM the mass simply slid and did not stick enough to be spread uniformaly on the surface.
By itself glue-paste speads smoothly. The glue-paste and pulp mix must not correctly made. When I tried a drier mix the paper fibers balled up like little pebbles. I had thought the pulp mix would spread like plaster spackling:(
Any Advice on where I am going wrong?
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It sounds like your pulp is good. I don't think it's your pulp recipe. I have had the same problem before with getting pulp to stick to a surface. I found that if you apply the pulp, then put plastic wrap on it , you can squish and mold the pulp with your hands through the plastic wrap. After the pulp is the way you want it, peel the plastic away and let the pulp dry. If you have to work the pulp again, do it through the plastic.Tammy
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The latest try at a making a model boat using PM is meeting with great success. The last coating(layer) consisted of pulp mix of PVA wood glue and tissue. After applying as a paste using a putty knife I covered the hull with a sheet of poly-wrap and pulled the sheeting tight which smooth the paste. Then I used a wallpaper seam roller (2 inch wide) to roll the pulp to a very thin uniform coating. The poly film was then pealed off.
When dry the surface was very hard (because of the glue content). This made a good sandable surface. Sanding almost finished the preparation.
Finally the surface was covered (and any surface pits filled in) using automotive spot putty. Then the final coating was sanded smooth and is now ready for painting.
The hull easily pulls off the mold. I'll add sheer strips and decking soon.
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Hoorah!
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