by dat8962 » Oct 3rd, '05, 18:18
I've heard that one of the strongest is the IT that's used in the Spider pen but I can't qualify this. Personally, I've found than the stuff used in the ITR from Magictricks.co.uk has been more than adequate for the effects that I've used it for (straws, paper money, silks etc.)
Member of the Magic Circle & The 2009 British Isles Close-Up Magician of the Year
It's not really an optical illusion - it just looks like one!