What are you using for forms? particle board, OSB, or plywood?

As I understand it, sealing the edges with shellac is supposed to help hold in the staples, and if it is used in stapleless construction it will just be an aid in sealing the edges, and keeping the forms from yielding loose splinters from end grain ood tha might get a really good bond to the hotmelt glue.

The reason for the tape (or wax) on the edges of the forms is so that any glue on the edges of the strips, which might ooze out of the joint, will not glue the hull to the forms. The tape (or wax) is there as a kind of non-stick surface. Given that, I'm surprised the hot-melt glue sticks to Spidey's duct tape, and I'd be surprised if you got a good grip on masking tape with hot-melt glue. It is very easy and cheap to make a quick test of both before puttng either on your forms, though.

Lay a scrap of the material you used for forms on a table, and just lay a strip of masking tape, and a strip of duct tape 6 inches from the edge. I don't think it is worthwhile testing wax, but you might also paint a small area with some shellac. Put a dab of hotmelt glue on each, and cover with a foot long piece of wood strip, aligned so half of it hangs over the edge of the scrap, and over the table. wait a few minutes for the hot glue to set up.

Start with the strip glued to the masking tape. Use a loop of string around the end of the strip that is overhanging, to support a plastic kitchen bucket, or an old paint can, and start dumping scraps into the bucket until either the tape lets go, or the hot melt glue does. Empty the bucket, mount it on the next strip and see if you can put al the weight back in. If not, then this is the weaker of the two. On the other hand, if it holds all the weight that the first one took, see if you can add more. Maybe you can get an idea of how strong the bond is.

Your control, of course, is to just put the hot glue directly on that scrap you made the forms from and do the test again. If that holds better than the tape, then forget the tape. Add weight until the holt-melt glue bond breaks and see if it rips wood fibers from either the strip or the form. If it is going to do any damage it would be best if the form was sacrificed.

The larger the glued area the stronger the bond, so try to keep things common, and use small drops of the hot glue for your test.

Hope this helps.

PGJ