All About Pocket Knives

Picked up a couple of old folders with buffalo horn scales

I knew one had a crack at the rear pin and planned to use it as a project knife and strip it down -

sitting in my hand there is so much character i want to keep the scales

I've not tried to repair cracks - not looking for perfection just to stabalise it

can anyone offer some advice - its solid enough I just want to fill the crack so it doesn't get worst or break off

Zap-a-gap is some pretty good stuff for cracks.
How large are these cracks?

Yep, like Mike said, Zap a Gap. It comes in thin and medium and I heard someone here mention it comes in a gel formulation too. I’ve used the thin and the medium but have not used the gel (yet). It’s good stuff.
Jeff

its a line above the pin and a crack the other size, I can just about slip my thumb nail into it

I use all 3 flavors of Zap-a-gap. First, clean the crack as best you can. I use a q-tip with rubbing alcohol. Sometimes, if there is a lot of gunk in the crack, I use a sharp sewing needle to scrape it out first. Then use the thin Zap, and let it sit a day. Then the medium. if the crack is large, wait a day, then fill with the gel. If you use the gel, you likely will have to sand off the excess. Good luck! P.S. don't get it on your skin. I have actually gotten my fingers stuck together!

What they said. Zap=a-gap.