PHOSPHOR OMITTED STAMPS- ARE THEY GENUINE!!

Buyers of phosphor omitted stamps must check with the seller that they are mint not used as the phosphor can be affected when stamps are soaked off paper. I have recently discovered with phosphor stamps that the coating can be very,very hard to see once a used, unfranked stamp is soaked then left completely flat to dry.The band/s can still be seen on machin stamps but the phosphor will not show up clearly under an ultra violet lamp, making it appear as though the phosphor is omitted. On definitives this can be even harder to see so be careful not to buy if you do not own a u.v lamp to check for yourself.This also applies to arabic gum stamps which appear to have a gloss finish on the reverse side of the stamp, again buyers must check with the seller that the stamp is mint and unused. Obviously when an unfranked stamp is soaked the gum is removed almost 100% so giving the stamp a matt finish where the gum once was, which then appears like PVA gum.How many buyers can say with confidence that a stamp that was bought as a mint unused one is actually a used but unfranked one?.How do I know all this? Well, I recently bought a large quantity of supposedly pre-decimal mint machins and was checking for the different varieties and found a large number appeared to have the phosphor omitted and thought I had hit the jackpot. But after further inspection I found these "omitted" stamps had been used but were not franked and the phosphor had obviously been affected. I even thought they all had PVA gum but realised the 1d olive with a centre band was only issued with arabic gum (which has a shiny finish ) so it just goes to show that after all these years of collecting stamps I can still learn a lot.It also proves that you need the correct equipment to collect stamps and avoid the sharks out there who just want your money!!!Thanks for reading this and I hope it was of some use.