Lol - thank you Steve - excellent videos and they'll be very useful to a lot of people. One problem we have here in Ireland is that it seems very few shops if any sell acetone. I haven't been able to find any so I turned towards cheap nail polish remover which contains acetone but to the same purity.
For mylar sails I found -thanks to my wife- that using baking soda works wonders to remove sail numbers in permanent ink. I put a bit of this white power in a bowl with just a little bit of warm water to make a paste of the baking soda. then I also use kitchen towels to wipe the ink on the sails. you need to rub a little more then on your video with the acetone since this is a paste but it is safe for numbers that overlap sail seams. Once most of the ink is gone I finish off with my nail polish remover to wipe off the last bit of ink to make it really clean again. And like you I put the sail to the light to see if it is really clean.
You should try it some day and tell me what you think...
For now I'll try to be more persistent with clearing the number with the nail polish remover as I suspect it to be less effective over pure acetone.
oh and as for the rhum I think I stick to wiskey or a pint or 2 of guinness - and it looks like I'll new a few good CDs
Thanks again Steve. and good luck to get to cape town