This tutorial attempts to outline a process for joining two pieces of hardened plaster.
Even though pieces can always be joined using familiar white glue, one has to wait
for the glue to dry, which can slow things down, or maybe the two pieces don't have the kind
of smooth, relatively flush surfaces one would prefer when trying to develop a strong bond
between them.
This approach to joining pieces largely overcomes these potential short-comings.
Start with two pieces of hardened plaster you wish to join.
These two pieces fit together relatively "flush", but this is not a hard and fast requirement.
This technique (i.e. joining two pieces of hardened plaster using fresh plaster)
also works even if there is a relatively large gap between the pieces. Ultimately, the key
is to position two pieces however you want them joined, then begin filling the gap with plaster.
Select the surface of the top piece that sits flush on the base piece.
Use a knife to slightly "bevel" the edges.
When you put the pieces back together, there should be a very slight "gap" all the way around the top piece.
Another view showing more clearly the effects of beveling.
Using the same type of "watery-plaster mix" as was demonstrated in the
Layering tutorial, repeatedly use your brush to transfer water & plaster to the small gap where the pieces join. You will notice that capillary action will "wick" the water into the gap and actually deposit fresh plaster
between the two pieces of hardened plaster. THIS IS WHAT YOU\'RE AFTER. Do this around the entire perimeter.
Avoid the temptation to "glob" a lot plaster at once...too much plaster on the brush at one time will prevent the capillary action you\'re after.
This is a close-up of one end before plaster was applied (plaster has already been applied along each length of the piece).
This is what the end looks like after applying the plaster.
The "welding" is more or less complete at this point. The gap around the perimeter is now filled with fresh plaster that connects the top and bottom pieces.
Be sure to keep in mind there are a LOT of variations on this approach to joining pieces of plaster.
While the newly applied plaster is still soft is a good time to clean up any joints that might have received more plaster than intended. You might even want the "weld" to have a "fillet", in which case you could continue to add more plaster. There are a
After the plaster set I was unable to separate the two pieces using only my fingers. I had to use a small chisel under one end to pop the pieces apart. This image is intended to show the effectiveness of the beveling in distributing plaster between the two surfaces.
