Re: "Marine Glue"
- From: basilkies@xxxxxxxxx
- Date: Thu, 14 Jul 2005 08:27:58 -0700
Just to add to the message below, I am almost finished with a 23 foot
pacific vee dory. I have spent just over 600 dollars in epoxy on it
and $390 on screws and bolts.
Next time I will look into a drum>
On 9 Jul 2005 14:46:21 GMT, ag384@xxxxxxxxxxxxxxxxxxx (William R.
Watt) wrote:
>
> (andrewoliv@xxxxxxxxx) writes:
>> I am in the process of building a bankers dory. The Bill of Materials
>> calls for Marine Glue.
>>
>> My partner wants to use an epoxy instead. Anyone been down this road
>> before?
>>
>
>When was the design published? Is it a reproduction using historical
>materials?
>
>Dories are traditionally held together with mechanical fasteners, ie nails
>or screws. When wood gets wet is swells and closes the gaps so the boat
>doesn't leak. On some boats, although I don't think on dories, the cracks
>between the wood was stuffed with something that would also swell up when
>it got wet and seal the cracks better. It's a bit tricky because if the
>gaps are too small the wood fibres will get crushed when they swell and
>lose their ability to close the gaps.
>
>Up until the 1930's all sorts of things were used to try to stop leaks on
>boats. They were usually called "calking" or "bedding" but not "glue".
>Glue is supposed to be an adhesive, ie holds things togehter. Glues used
>to be proteins, "glue" and "gluten" being from the same latin root. So
>it's the protein in wheat flour that makes four-and-water paste stick, the
>protein in milk which makes casein glue, the protein in skin and scales
>that makes fish glue, and the protein in hooves and hide that makes
>animal glue. None of the glues is very waterproof.
>
>In the 1930's two new adhesvies were made from (petroleum?) chemicals,
>urea formaldehyde and rescorcinol. Urea formaldehyde is generally called
>"plastic resin" glue. It is water resistant but will break up if heated,
>say in boiling water. It is called "cold waterproof", and sometimes
>"weatherproof". Resorcinol adhesvie is waterproof. Both of these are thin
>glues which have to be applied to pieces which fit closely with no gaps
>more than 1/8 inch. They both dry hard and brittle. When sold as "marine
>glue" the urea formaldehydde is a dry powder mixed with some wheator rye
>flour to thicken it. Weldwood is (or was) a popular brand. I used a
>different brand on one small plywood boat (Dogskiff) in combination with
>wood screws. Where the parts didn't fit well I mixed in some sawdust for
>extra thickener. It worked fine. There are some limitations like having to
>be above 70 degress to cure. I was building indoors in winter and threw a
>tarp over the boat and put a space heater underneath to "cook" the
>plastic, a common practice. I've never used resorcinol but have read
>accounts of others who have. The plywood motor torpedo boats and the
>plywood aeroplanes (Mosquito light bombers) used in WWII were glued with
>urea formaldehyde.
>
>Epoxy (epoxides) is one of the post war chemical adhesives. ("Glue" should
>probably be reserved for protein adhesives). Epoxy is waterproof and very
>strong. The drawbacks are cost and toxicity. Cost is always an arguable
>point and there have been many arguments about it. It becomes less of a
>factor on large boats for which epoxy can be purchased in volume.
.
- References:
- "Marine Glue"
- From: andrewoliv
- Re: "Marine Glue"
- From: William R. Watt
- "Marine Glue"
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