Celluloid

At the first sign of "nitro rot" you should remove the offending material from your guitar and case. When nitrocellulose plastic breaks down it often "gasses" which can be very harmful to the inside of the guitar case, hardware plating, and the guitar finish.

Gibson actually fashioned this celluloid block to reposition the pickguard so that a DeArmond Adjustable Rhythm Chief could be properly installed under the strings of this 1964 Gibson Super 400 C. Over time it started breaking down, dissolving the finish of the guitar which is now sticky to the touch, years after removing the block.