Experimented a lot in the past with float mounting. I wanted archival framing; a method that would allow me to remove the painting at any time with no residues from tapes or adhesives.
I got into discussion with framers I met online (pre-Facebook.) I wish to credit but I have forgotten the names since my ICQ account is gone. Those of the younger generation are probably wondering what ICQ is. ICQ is one of the earliest chatting platforms.
Anyway, on a discussion whether float mounting results in more tendency to warp and buckle as they are not anchored more securely on the base board, one or two said untethered mounts might work to my advantage since I happen to mention I live in a tropical country. It may allow the painting to expand and contract within the holders with changes in heat and humidity. If it was more permanently mounted, once the paper expands, the anchor will hold the edge in place and some areas will bulge and others contract, more pronounced warping observed.
Early bulky prototype. Flap folds towards the painting. The holders were made from the same watercolor paper I used for the painting and were secured on the base board with acid-free paper tape. Laying the passepartout over the setup locked the painting in position. This required a slightly wider paper border allowance and needed further improving.
It worked though. When the painting was sold to a client abroad, I was able to remove the painting from the frame safely. It was free of marks, adhesives and discolorations. DIY archival.