Tonga Pacific Islands Stamps Soaking Them?

Has anyone had any experience soaking these unusual shaped stamps form Tonga? I have a number of them and do not want to destroy any of them. I have a horrible feeling that some are self adhesives.

Have given these stamps all that I know about water based gum and got no where.

Have just tried lighter fluid (shellite) and have the stamps off paper easy as but am having trouble with sticky residue on that back of the stamps at the minute. So these stamps have an oil based gum.

There was a video on the Youtube site referenced to on Stamp Community about using shellite to get modern stamps off paper and also using a steel rule to help scrape the gum residue off if I remember correctly.

Here it is after I searched for it:
http://www.youtube.com/watch?v=nWMcVYgIZjM

Nice Tonga stamps! I like them, haven't seen them before.

I know I have some of those Sierra Leone map stamps on paper around here somewhere, hope they are not as difficult.