Louis Michaud
LOVES Wooden Canoes
I got frustrated because traditionnal bedding compound is not available in Canada. Shipping from the US would be too expensive. I don't like the polysul.../caulks/sealants/etc. So, I followed Mike Cavanaugh's lead from his brushing liquid post and went to look at the MSDS. The numbers are weigth %. No mention is made of linseed oïl in no.1 or 2 but they are known as being linseed oïl based.
Compound no.1
mica 1-5
silica 50-55
mineral spirits 5-10
Compound no.2
talc 25-50
limestone 10-25
kerosene 1-10
naphta 1-10
seam compound
limestone 30-50
zinc oxide 20-30
barium sulfate 10-20
talc 1-10
silica 1
raw linseed oïl 10-20
kerosene 1-10
French boatbuilders use "bliouz" a traditionnal bedding compound made of clay, raw linseed oïl, red or white lead and dryers. If the gap between the parts is large they add chopped oakum to the mix. They also recommend to oïl the parts before smearing on the compound, otherwise the wood will pull the oïl out of the compound and it will not remain flexible.
The zinc in the seam compound is a UV blocking pigment and a fungicide. The barium is also a UV blocker.
I already had all the basic ingredients in my shop. Silica used for the filler, chalk and clay for the powder. Lineseed oïl and copper naphteate(sp?) or zinc naphteate as a préservative. From left to right: silica +zinc, clay+zinc, chalk+zinc and chalk +copper. The proportions were done according to the desired consistency and agree with the % given. With the big variations of % this is not a precise formula. I used the clear zinc preservative because it is mostly mineral spirits and goes well with the no.1 compound. The compounds take a few days to skin over so it can be painted. How does the commercial stuff behave?
I like the clay over the silica. It gives a creamy consistency like mayo that holds its shape. The silica is more like peanut butter. When it dries the chalk mix becomes more brittle on the surface then the other two, maybe not enough oïl.
So, I mixed a small batch with boiled linseed oïl, clay and zinc that I will be using for bedding stem bands. I had to give the compound a name so I knew what was in the can. I will report in a few years...
Best,
Louis Michaud
Compound no.1
mica 1-5
silica 50-55
mineral spirits 5-10
Compound no.2
talc 25-50
limestone 10-25
kerosene 1-10
naphta 1-10
seam compound
limestone 30-50
zinc oxide 20-30
barium sulfate 10-20
talc 1-10
silica 1
raw linseed oïl 10-20
kerosene 1-10
French boatbuilders use "bliouz" a traditionnal bedding compound made of clay, raw linseed oïl, red or white lead and dryers. If the gap between the parts is large they add chopped oakum to the mix. They also recommend to oïl the parts before smearing on the compound, otherwise the wood will pull the oïl out of the compound and it will not remain flexible.
The zinc in the seam compound is a UV blocking pigment and a fungicide. The barium is also a UV blocker.
I already had all the basic ingredients in my shop. Silica used for the filler, chalk and clay for the powder. Lineseed oïl and copper naphteate(sp?) or zinc naphteate as a préservative. From left to right: silica +zinc, clay+zinc, chalk+zinc and chalk +copper. The proportions were done according to the desired consistency and agree with the % given. With the big variations of % this is not a precise formula. I used the clear zinc preservative because it is mostly mineral spirits and goes well with the no.1 compound. The compounds take a few days to skin over so it can be painted. How does the commercial stuff behave?
I like the clay over the silica. It gives a creamy consistency like mayo that holds its shape. The silica is more like peanut butter. When it dries the chalk mix becomes more brittle on the surface then the other two, maybe not enough oïl.
So, I mixed a small batch with boiled linseed oïl, clay and zinc that I will be using for bedding stem bands. I had to give the compound a name so I knew what was in the can. I will report in a few years...
Best,
Louis Michaud
