Making the Back Panel:
Your project is now together
in one piece, but it is still very fragile. Very few of us can cut
so accurately that the bond between the individual pieces will be
solid and secure. The gluing is more of a tacking job then anything
else. For this reason you need a firm back on all your Intarsia
What to Use?
Baltic birch plywood is the product I have found works the best.
It always comes in a 5' x 5' sheet, or pieces cut down from there.
It has more layers of lamination then normal plywood, so tends to
resist warping better than most. A laser is used to scan the sheet
for voids. In theory all baltic birch sheets should be void free,
so when cutting the outline for your project you should not run
into holes between the layers.
Lay your work on the plywood sheet, and trace
around the outside edge. Cut just inside your pencil line so the
plywood ends up being slightly smaller than the work.
Check for accuracy and adjust as needed so
the plywood does not show from the front. Sand the edge. Often I
will stain the edge of the plywood, walnut, as this tends to make
it less obvious on the finished product. A brown marker also works
well. Think that one through though, as it relates to the colour
in your work.
Sand off any stain that has dripped around
the back edge of the plywood, sign the plywood and apply a finishing
coat to seal the back.
Spread a layer of good quality wood glue
to the front surface of the plywood and lay your work on top. Align
it appropriately and use a damp cloth to clean up any squeeze out,
as necessary. Weight it down while it dries. Touch up the finish
with a spray tin as necessary.
Patterns for Sale by site owners
I have cut the backing first and then laid up and glued my pieces
to the backboard, but historically I have found that every time
you lay up your pieces they tend to position themselves in a slightly
different way. Then the backing board never seems to fit accurately.
Making fine adjustments to its shape is difficult when all the wood
pieces are glued in place.
By tacking the pieces together then cutting
the back panel, you are assured of a good fit. The caution,is to
handle it carefully, up until you have glued it to the plywood.