Filler cracks: Practical solutions??

[Lazy Jack]

Recanvassed in 2012, filled with well proven traditional oil based alkyd/silica/linseed six-week cure stuff from tried and true reliable source, painted with Benjamin Moore D.T.M. Super Spec Low Luster Alkyd Enamel signed by a few submerged rocks and logs here and there...



The filler seems to have developed some cracks:



Located in various patches along the bottom with fine cracks in a reticular pattern, somewhat like a dried mud-flat



I noticed traces of this earlier this spring, sanded and added a few more coats of paint to the bottom of the boat. It got me most of the way through this season without any leaks, but now it seems to ooze through the cracks pooling in the bilge as I paddle heeled over.

What would be a practical solution? Thin coats of shellac to fill in the cracks then paint over? Re-canvas and re-fill?

 

[Dave Wermuth]

I had that happen using traditional filler. I think either the filler may have not turned out right or, more likely I did not rub it in well enough when I put it on. I suggest that you use a random orbital sander and don't spare the horses. After a thorough sanding I'd use primer and then paint, hand sanding in between. Also, you might consider a high performance interior/exterior Latex primer/sealer over the well sanded hull and then prime/paint with oil based. the latex might give a bit of flexibility against cracking. I have used it for filler with no problems lately.

 

[Lazy Jack]

Thanks Dave

I do believe that the problem stems from my not being able to adequately rub the filler in in some spots. Despite thorough mixing throughout the procedure and pouring out separate aliquots from the can, It seemed to thicken up as I progressed until I was adding thinner just to get it to suggest it was soaking in a little.

I guess maybe I'll try sanding no farther than the weave of the canvas and try a couple coats of the thick latex primer like you suggest.

 

[Dave Wermuth]

I wouldn't lay it on thick. A couple thin coats are better. I use a plastic auto body squeegee to work it in well. Also, you may be just fine with a good primer and paint without the latex.

 

[goldencub]

Dave - I thought it was not good to apply oil based paints over latex based paints ---- or was that vice-versa???? Al D

 

[Dave Wermuth]

Me too. I always thought it was a no-no. But, I think paint science has improved. The primer I use gets used on everything, pipe, concrete, wood, block, etc and it says you can paint oil over it. Sherwin Williams Pro-Block is the name. You can probably visit the website for the technical stuff.