Larry Westlake
Designer/Builder
I think the following information will be of interest to beginners who intend to mix their own filler.
In a search of the WCHA forums, the only thing I could find about double-boiled linseed oil was one filler recipe posted which specified it as an ingredient, and a brief discussion of that recipe.
Several people reported that they used that recipe or a similar one. Mike Elliot of Kettle River Canoes used to have this same or a similar recipe posted on one of his web pages.
Mike's recipe and the recipe in the thread mentioned above appear to be based on a recipe on the WCHA "Fillers" legacy web page, with the important difference that the "Fillers" page recipe does not specify "double-boiled" but only "boiled" linseed oil.
NOTE the caveat on the WCHA page about differences between historical and current materials (and I would add, how they are labelled and named): it is critical for beginners/amateurs mixing their own filler to know that most so-called "boiled linseed oil" in the 21st century is actually almost the same as raw linseed oil, and has not been boiled or anything like it. In all cases that I tested, the modern product of that name lacks the qualities required for canoe-canvassing, and is totally unlike the "boiled linseed oil" of yesteryear. I tested 5 different brands and none of them were what the words indicated they were.
As we learned from Watergate, "People don't lie anymore, they just change the meanings of the words."
Double-boiled linseed oil, as specified by Mike Elliot and by the thread recipe (but unfortunately not by any of the "Fillers" page recipes), is what you must use for canoe canvassing. And just in case someone unilaterally changes the meaning of "double-boiled" on us, here is the test for the necessary quality: Just brush an even coat of the oil on to a piece of cedar and let it dry for a few days. If it is not tough-dry and non-tacky to touch after 2 to 3 days at 65 to 70 degrees F, its not what you want for filler. Make sure it hasn't just soaked into the wood so much that it seems dry (which uncured oil can do) but has actually dried to a surface film.
Raw linseed oil and fake boiled oil will take approximately forever to dry. One test I did on #10 canvas took 5 months to dry through (tested by cutting) even though hung so exposed to air on both sides, and heavily doped with Japan drier.
Failure of the oil in the filler to cure seems to be one of the causes of the dreaded "Blisters". Search the forums for "blisters" for an enlightening wealth of woe on that subject.
Larry Westlake
In a search of the WCHA forums, the only thing I could find about double-boiled linseed oil was one filler recipe posted which specified it as an ingredient, and a brief discussion of that recipe.
Several people reported that they used that recipe or a similar one. Mike Elliot of Kettle River Canoes used to have this same or a similar recipe posted on one of his web pages.
Mike's recipe and the recipe in the thread mentioned above appear to be based on a recipe on the WCHA "Fillers" legacy web page, with the important difference that the "Fillers" page recipe does not specify "double-boiled" but only "boiled" linseed oil.
NOTE the caveat on the WCHA page about differences between historical and current materials (and I would add, how they are labelled and named): it is critical for beginners/amateurs mixing their own filler to know that most so-called "boiled linseed oil" in the 21st century is actually almost the same as raw linseed oil, and has not been boiled or anything like it. In all cases that I tested, the modern product of that name lacks the qualities required for canoe-canvassing, and is totally unlike the "boiled linseed oil" of yesteryear. I tested 5 different brands and none of them were what the words indicated they were.
As we learned from Watergate, "People don't lie anymore, they just change the meanings of the words."
Double-boiled linseed oil, as specified by Mike Elliot and by the thread recipe (but unfortunately not by any of the "Fillers" page recipes), is what you must use for canoe canvassing. And just in case someone unilaterally changes the meaning of "double-boiled" on us, here is the test for the necessary quality: Just brush an even coat of the oil on to a piece of cedar and let it dry for a few days. If it is not tough-dry and non-tacky to touch after 2 to 3 days at 65 to 70 degrees F, its not what you want for filler. Make sure it hasn't just soaked into the wood so much that it seems dry (which uncured oil can do) but has actually dried to a surface film.
Raw linseed oil and fake boiled oil will take approximately forever to dry. One test I did on #10 canvas took 5 months to dry through (tested by cutting) even though hung so exposed to air on both sides, and heavily doped with Japan drier.
Failure of the oil in the filler to cure seems to be one of the causes of the dreaded "Blisters". Search the forums for "blisters" for an enlightening wealth of woe on that subject.
Larry Westlake
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