Dealing with tree sap

[8squared]

Is there an effective way of dealing with it when it reveals itself before or during a project.

Made my daughter (well she made me make one) a wooden rainbow.

Had a clean scrap of 2x5 so used that but during cutting the sap revealed itself, at first it wasn't a problem as we wiped it off and rubbed a little sawdust on it that seemed to stop it...

but after finishing the thing and leaving it over night we woke to find what looks like a jar of sap had been emptied all over the top of the kitchen cooker... of course it's spoiled the work piece a bit.

 

[Sgian Dubh]

There's no way I know of to set the pitch hard in a workshop or home environment which would prevent it weeping out of softwoods after you've made something with the material. In theory, kiln operators can set pitch by running a programme of high heat, about 75º - 95ºC (~170 - 200ºF), for about two hours once the wood has reached this target temperature. This operation usually takes place towards the end of a run, if it's undertaken at all.

This doesn't help you. The only thing I've ever been able to come up with has been to be patient, let whatever wants to weep out as much as it can, then seal the opening with something like an epoxy filler, and finally apply a finish good at sealing in pitch or resin. Painters use knotting, a dark brown shellac based product, and I've often just used a straightforward shellac as a knotting substitute. There's also Zinnser BIN, a commercially made shellac based sealer product.

In truth, I've not found any of these products or solutions to be infallible - some weeping pitch pockets seem able to defeat almost anything. I guess the best solution is to reject use of anything that's obviously going to weep badly, but it's not always easy to spot problem bits of wood until it's too late. Slainte.

 

[thetyreman]

I had a piece of pine like this on my tool chest, I just kept wiping it with meths and eventually it seemed to stop seeping, left it for about 3-4 weeks, it was sealed with de-waxed shellac which seemed to help, then painted over, so far there's no evidence of it coming through the paint, but I'll have to check again in a few years and see if it causes problems.