Raising I.D.numbers

Does anyone know the process to acid raise Harley numbers?What type of acid? Thanks.

Use muriatiac acid sparingly. Do it outdoors. Don't breathe the fumes.

To contain the acid, use wax to build a dam around the boss. Try alcohol first (low surface tension) to level the case. Dilute some acid with water for a test. Apply acid with a Q-tip in several passes. If it bubbles immediately it's strong enough, if not use less water.
When you see something appear, stop the acid with baking soda and rinse. Scuff the surface with Scotch-Brite etc. to see what you have. If too faint, repeat.
This will not work if the numbers have been completely ground off to roughly 2.5 × the impression depth (.150"?), starred or X'ed over, or welded.

The restoration process requires the surface to be smooth prior to applying the acid. It must be applied with a qtip, and on aluminum it takes quite a while. If you surround the area and flood it your number will disappear. I think we used a diluted solution of Nitric acid.
Scot