Thicken filler?


Enthusiastic about Wooden Canoes

I mixed up the posted filler recipe but replaced the volume of silica with a matching volume of glass micro balloons. Everything seemed to go on ok, though it seemed a little thin- I should have held off on the paint thinner. I have done another boat with the silica filler but I remember it being a bit thicker.

Problem is that my stem seams are not getting covered very much and I am continuing to add layers.

I had to mix a second, half batch of filler and I used my 325 mesh silica in the recipe. Still thin.

I’m out of silica at this point, maybe I can add some micro balloons and increase the filler body a bunch to a putty and slather it on the stems?

I also have epoxy filling silica but that is really fine stuff.

am I going to have a flaky mess?
I swear I responded to your post within an hour of when it was posted, but I do not know where my reply went! Love computers.
I had a similar experience when I used glass beads in filler and wish I had used less mineral spirit. I added silica, but probably not enough, as the filler was still thin. It took forever to set, and I didn't finish the canoe for a year. After the filler was sanded, the surface felt soft, and so I painted it with epoxy prior to primer and paint. That worked.
But to your problem: if you have some filler left over, and it has set around for a day, then the silica will have partly settled. Can you carefully remove some of the top liquid and scoop out some of the solids at the bottom and use that to coat the areas of the canoe where filler seemed thin?
I was going to use some thickened epoxy as back up if everything flakes off but maybe I would just recanvas, we will see.
This is my experimental canoe, so I need to try things.

I thickened my half batch of silica filler with epoxy silica and micro balloons until it was more mud like, not quite ketchup consistency. It tended to smooth out after being spread on as the fillers settled. It did dry overnight a bit and is skinned over to the touch so I’m hoping it dries properly and stay stuck!

After the 3-6 weeks of drying I’ll see how it look- I’m sure if I sand and it falls off I can just prime and paint and everything will look fine.

has anyone thought of getting a specific gravity of filler? Like measure out 100 ml of filler, and weigh it? There should be a range that is the appropriate weight if all of the ingredients as relatively the same and in proportion, then you would increase or reduce the SG with thinner. It works with ceramic glazes, but water is the thinner for that.