Stamp Mounts In Minkus Album

Just received a Canada Album with Minkus Sheets inside.

All the sheets contain Stamp mounts I have never seen before, they are 3 layers, 2 plastic and 1 black cardboard piece. They also only have 2 glues edges in 90 degree format.

Question is "were they purchased that way or are the custom made? The Album has many different shapes and sizes of mounts. From Single Admiral size, horizontal pairs and blocks of 4.

The top plastic layer is folded over to the left for clarification and the 2nd plastic layer has a folded top right corner.




As you can see on this Admiral page, the stamps do not sit centering in the mount.



I have noticed the "gums" on some of the mint stamps just dont look right. I am wondering if the plastic is not philatelic safe.


Any ideas?

Trodent

The irregular glued edge on the bottom suggests that all are hand made. My very old Minkus Canada album did not have mounts. I do not know what was used to become the mounts so can not comment on the safety of the stamps in them.

The mounts definitely look "after market," that is, added by a previous owner. I'm not aware of Minkus ever offering a hingeless album.

They look kind of familiar. They remind me of the black mounts that had a plastic layer that folded over the edges and was sealed from behind. These wound up with a sticky glue on the back. A real pain to remove the stamps.