Rob I was trying to do the same repair on a horn butt plate on an Ideal that I just bought. I tried to use acrylic paint. The color looked fine but the acraglass did not get hard. I am not sure if the paint caused the problem or the acraglass was just old. It also did not stick well to the horn. I have not purchased new acraglass yet to see if it solves the problem. Has anyone ad problems with acraglass on horn?

Bill G.