Wheat starch vs. sponge blasting

Never heard of sponge blasting. Wheat starch might work; however, I'd look into a cryogenic system.

I have heard that walnut shell media ⇦this on eBay or Amazon [affil links] or pecan shells were used for that exact purpose. Media size/ distance /air pressure can be adjusted as required.

Hi Ciaron,

My experiences with the removal of paints, varnishes and sealants from aluminium or other light metals (including magnesium) are such that I have always used chemical means to remove them. Any of the standard Aerospace paint strippers based on methylene chloride will do the job on the paints for you, you may need a very light blast with something like walnut shell to remove residuals. For the removal of sealants I have tended to use a Chemetall product called Ardrox 6345, very good on even fully cured polysulfide sealants, not so good on the silicones, but with persistence will work. For fresh sealant you could consider using Elixair Skywipes (make sure it is the non-lanolin version).

Carbon/glass composites are a very different animal as you well know, the solvent option really isn't there for that. Here it has been good 'ole mechanical removal for sealants (with scrapers and a steady hand!) and blasting with walnut shell for paints. Labour intensive and long winded. I'm sure others will have better ideas, but that is always the way I have done it.