After you have gained some experience soaking stamps, chances are you have encountered stamps that won't soak off. There are several reasons for these stamps having glues that are not water soluble. Stamps from western countries that will not soak off are usually the result of someone illegally reusing stamps not cancelled by the PO (skips). In reusing the stamps, these people have used things like model glue because it dries fast or because it is all they had. Some of these glues can be loosened by solvents, but often the the solvent strong enough to loosen the glue will ruin the stamp. Chalk these stamps up as lost causes and throw them away. In some countries, stamps are issued without gum because of the usual high humidity. The local PO has a community glue pot that often contains glue not water soluble once it dries. This problem is often encountered on stamps from Taiwan (WWII to the mid 60's), Red China, India and sometimes Pakistan. There is not much you can do with many of these stamps. Often the paper on which the stamp is printed will fall apart before the glue loosens up.

A more current problem involves self-adhesive stamps. Some self-adhesive stamps are designed to be able to be soaked. Others are not. I have personally had trouble with the self adhesives from France and Spain. The Bear stamps from Finland have also resisted, for the most part, being removed from the adhered envelop paper. The best you can do with these is to trim them closely and mount them ��as is��. Always separate the self-adhesive stamps from the regular ones. Also sort them by country. Self adhesives almost always take longer than regular stamps to soak off and some don't come off at all. Practice will give you a feel for their particular needs.

One problem that seems to crop up all the time is stains from airmail envelops and purple cancels. When soaking, if you notice that the purple cancels have run or that the backs of some of your stamps are stained red or blue from airmail envelops, take these stamps before they dry and place them in a container of milk and place the container in the refrigerator overnight. The next day remove them from the milk and soak them again a couple of times to get the milk out. Often the stains are removed by this process.

The quality of the water you use can, in some rare cases, affect the condition of your stamps after they have been soaked. If you live in one of those areas that have heavy concentrations of acidic minerals in your water, you might consider using treated or distilled water to soak your stamps. Using treated or distilled water for most people is a waste of money.

When soaking stamps from before WWII, you will often encounter gums that take quite a while to loosen up; and even once the stamps have floated off the paper, there will remain a large amount of slimy gum on the back of the stamp. It is important to get these residuals off. If you don't, you will have problems with the stamps curling as they dry. The best way to remove the remaining gum is to very gently and carefully rub off the remaining gum under water. Practice with cheap stamps first. If you are ham-handed with this, you will ruin the stamps.