Timberjack
Curious about Wooden Canoes
Early May, 2012: Ah, yes. The microballoons.... Well, I mixed up the filler per a common formula—boiled linseed oil, exterior alkyd enamel, thinner, a bit of varnish, and Japan dryer, but substituted the glass bubbles (microscopic indeed) for silica. Instructions were to substitute volume for volume, and that a volume of bubbles equal to volume of silica might weigh a pound and a quarter or so.
So I mixed it all up with a beater on a drill, which went fine, and ended up with a medium batter. Dipped in my brush and applied the first load to the canvas. All the liquids were instantly sucked out of the mix, leaving a damp and almost weightless paste on the surface which was impossible to work into the weave with the brush. I ended using the brush to transfer the filler to the canvas, and then mashed it into the weave as best I could with my gloved hand. In the process, quite a bit of the paste flaked off onto the floor. But I was committed, and kept at it. No turning back now.
Got around to the last quarter and wondered what would happen if I wet the canvas first. Happened to have a can of home-made oil-varnish wood finish (roughly equal parts oil, varnish and thinner) on the bench, so I brushed this on the last of the bare canvas, and then hit it with the filler. The filler stayed brushable. End of coat #1.
Kept checking on drying progress, and gave it a final glove smoothing at the right time. The area I had wetted before applying the filler took several hours longer to become workable, as you might expect.
The following day I inspected, knocked down any ridges, and applied a second coat. Brushed on well and didn't use much, since the weave was already saturated. When the second coat was dryish (but not cured, of course) I went over the whole boat with a 100-grit flexible sanding block to even out the application--get rid of ridges and rough spots--and dabbed on a bit more in a couple of places.
The hull is now hanging from the shop ceiling. No hint of the canvas texture showing. Surface looks wonderful, although it is soft/powdery to the touch, nothing like silica filler. It will hang there until mid-July when I return from Montana. Hope it will have cured good and hard!
18 July, 2012: The filler has not cured “good and hard” after nine weeks. In fact, it seems no harder than it was five weeks ago. I rolled it up on horses so I could sand the bottom, and the edges of the horses left palpable creases in the filler/canvas. Need to move ahead, so will paint and hope for the best.
I’m curious how my experience with this compare with experiences of others, and if I made some grievous error in the process.
So I mixed it all up with a beater on a drill, which went fine, and ended up with a medium batter. Dipped in my brush and applied the first load to the canvas. All the liquids were instantly sucked out of the mix, leaving a damp and almost weightless paste on the surface which was impossible to work into the weave with the brush. I ended using the brush to transfer the filler to the canvas, and then mashed it into the weave as best I could with my gloved hand. In the process, quite a bit of the paste flaked off onto the floor. But I was committed, and kept at it. No turning back now.
Got around to the last quarter and wondered what would happen if I wet the canvas first. Happened to have a can of home-made oil-varnish wood finish (roughly equal parts oil, varnish and thinner) on the bench, so I brushed this on the last of the bare canvas, and then hit it with the filler. The filler stayed brushable. End of coat #1.
Kept checking on drying progress, and gave it a final glove smoothing at the right time. The area I had wetted before applying the filler took several hours longer to become workable, as you might expect.
The following day I inspected, knocked down any ridges, and applied a second coat. Brushed on well and didn't use much, since the weave was already saturated. When the second coat was dryish (but not cured, of course) I went over the whole boat with a 100-grit flexible sanding block to even out the application--get rid of ridges and rough spots--and dabbed on a bit more in a couple of places.
The hull is now hanging from the shop ceiling. No hint of the canvas texture showing. Surface looks wonderful, although it is soft/powdery to the touch, nothing like silica filler. It will hang there until mid-July when I return from Montana. Hope it will have cured good and hard!
18 July, 2012: The filler has not cured “good and hard” after nine weeks. In fact, it seems no harder than it was five weeks ago. I rolled it up on horses so I could sand the bottom, and the edges of the horses left palpable creases in the filler/canvas. Need to move ahead, so will paint and hope for the best.
I’m curious how my experience with this compare with experiences of others, and if I made some grievous error in the process.
