£
resin route
I
use a silicone with a shore rating of 20, there are
varying types of silicone and the shore is used to
describe the physical properties of the cured silicone
The shore hardness scale measures the hardness of
flexible mold rubbers that range in hardness from
very soft and flexible, to medium and somewhat
flexible, to hard with almost no flexibility at all. I find
that shore 20 is firm but still has the flexibility required
to demold lures with out to much effort. Silicones
come as Part A and Part B; part B usually being the
catalyst. Depending on the quantity of catalyst added
you can have a very slow cure or a rapid set up. I have
now come to the conclusion in that in most instances
a very slow cure is most beneficial, it can be annoying
waiting 48 hours to open up your mold but you will
generally get a much better result. This is because
any air bubbles will have longer to rise and eventually
evacuate the mold box.
Air bubbles in the silicone
This is a major problem for most modellers/lure
builders air mixed into the silicone creates thousands
of tiny bubbles that can get trapped inside the mold as
it cures. These bubbles are not a problem if they do not
form around the lure but generally there will be a large
portion of bubbles trapped on the lures surface. This
can leave the surface of the cast lures bobbly and in
need of sanding. I use a pressure pot to cast resin
(more of this later) and the pressure forces the resin
into the recesses left by the bubbles in the silicone.
Mixing the silicone
PIC 5: In order to prevent waste you will need to work
out the amount of silicone required to fill the mold box,
I do this by measuring the mold box and then using
this simple formula Height x Width x Length x 1.2
divided by 1000. In this case the box measured L
140mm x D90mm x 55mm, so 140 x 90 x 55 x 1.2
/1000 = 831.6, so I need around 830 gram of silicone.
I do not subtract the volume of the lure as I like to
have slightly more than I require.
PIC 6: Next I need to add the activator, this silicone
requires a mix of 100 parts silicone to 1 part activator
to get a nice slow cure so I weigh out 8 grams of
activator is a separate tub (it pays to use a separate
tub in case you accidentally add to much, I have tipped
straight into the silicone before and added too much).
PIC 7: Add the activator to the silicone and start to mix,
mixing slowly and carefully can to some extent
reduce the unwanted bubbles but as I shall be
Silicone -- Preparing and pouring
I usually mark out a rectangle on
the base with at least 20mm
clearance around the lure. I then
make the sides and the two end
panels. Now here is the little twist
I have developed to ensure you get
a very clean seam. I drill holes on
each of the two long side panels
which I pass metal rods, these
rods must be between the base
and the lure so you may want to
draw the lure shape on the panels
before drilling. Once all this is
ready I stick the panels together
with low modular silicone, this
means you get a nice leak free
seam and also means the box is
easy to remove from the finished
mold. I insert the rods and seal
around the holes again with
silicone. Stick the box to the base
and then stick the lure down
making sure that the rods do not
come in to contact with the lure.
Also you need to make sure the
lure is central in the box as this
makes cutting it out easier later. I
then leave this to set up overnight,
if you are using a wooden blank
you may need to give the lure a
spray with a sealer such as
smooth on super sealer to stop the
silicone sticking to the blank.
andthenusing
5
7
6
PAR T
ONE