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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

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