Lamination is a process where thin strips of material are glued together to form a multi layered composite that is stronger than an equal thickness of the original material alone. The increase in strength is usually the result of orienting fibers in different directions, and in part, from the adhesives used to bond the layers together (think about how plywood is much stronger and more resilient than a solid pine board).
Most modern wood fly rods (especially bamboo) are composed
of multiple triangular strips laminated together. Laminated construction gives
the rod more strength and power by off-setting weak areas in the wood grain
(knots), or bamboo nodes; but the lamination adhesive and rod varnish also
impart some additional reinforcement to the blank. Since my rudimentary fly rod
design involves a simple piece of wood sanded to taper, the wood grain needs to
be reinforced using alternate means. The pseudo-lamination process is designed
to impregnate the entire rod blank with polyurethane. The polyurethane helps bind
the wood fibers together and adds strength to any weak areas inherent in the
wood.
To set up the pseudo-lamination assembly you will need two
lengths of ¾" x 10' conduit, 10' of ⅝" ID clear vinyl tubing, a roll
of electrical tape, and two clamps. Start by positioning the tubing so the end
extends about 10 cm beyond the end of the two lengths of conduit; make a few
wraps of electrical tape to hold it in position. Now working your way down the
conduit, place a few wraps of tape every 20 cm so that the tubing is held
straight all along the lengths of conduit. Leave the last 20 cm of tubing loose
at the end to give room to fold the end of the tubing over and clamp it. With
the assembly prepped, the rod blank is pushed all the way into the tubing.
 |
| The top end of the assembly with some of the tubing extending past the conduit. |
 |
| The bottom end of the assembly with the tubing folded over and clamped. |
There are two solvent based polyurethane products that will
work best for the pseudo-lamination process: Minwax® Polyurethane,
and Varathane®. My preference is for the semi-gloss finish of either
brand – the gloss finish looks good but I feel that it produces too much
reflection while casting (and may spook some fish), while the satin finish is
too dull and produces a rod that lacks aesthetic appeal. Avoid any water based
acrylic products as these will reverse all of the work done drying and heat treating
the blank, and cause the wood fibers to swell.
 |
In the past, I have always used clear polyurethane to bring
out the natural look of the wood. But for this rod I am going to try using Minwax®
PolyShades (stain and polyurethane combined) in a satin finish shade called
Pecan (Varathane also produces a tinted product but it is not clear from the
label if it is just regular stain, or if it contains polyurethane as well). The
PolyShades Pecan finish should produce a slightly darker blank and hopefully enhance
the wood grain. Once the pseudo-lamination process is complete, I will finish
the blank off with a few coats of clear semi-gloss to get the final look I
want.
The polyurethane should be thinned out using 10-15% mineral
spirits to enhance penetration into the blank. A small funnel is used to slowly
pour the polyurethane into the tubing. Fill the tubing almost to the top and
clamp the upper end to prevent evaporation. Stand the assembly up in a corner
of the garage (I put the end in a bucket in case something leaks). Check the
polyurethane level daily and top up as required. After a few weeks the level can be checked
once a week. The rod blank should be allowed to soak for four months to allow
for full penetration – another two months are needed to fully dry the blank once
removed from the polyurethane. Note that summer is the best time to do this;
unless you are fortunate enough to have a heated work space (cold temperatures
will inhibit penetration of the polyurethane).
My rod blank has been soaking for a couple of weeks already
so it should be ready to start drying by the end of September.
No comments:
Post a Comment