Air gaps in blanks??

[Crungler]

Casting labels with alumilite. I've done mostly Sierra tubes and this happened occasionally, now that I've started casting labels in slimline it seems to happen constantly. After casting everything looks fine. After I round the blank out on the lathe and get ready to sand these gaps/discolorations appear.


any ideas??

 

[Curly]

Looks like you are breaking the resin free of the tube. One cause that comes to mind is putting too much pressure on the blank with the cones. Same effect as pressing components into a dirty (resin inside) tube.