Post by oldtimer52 on Feb 15, 2020 1:45:25 GMT -5
Now that I had the part prepped and the box made comes the
time to pour the silicone. I used the Rubber to Rubber
mold release to completely coat the inside of the box,
clay and part. This ensures that the silicone does not
bond to anything.
I used the formula listed in the instructions from
Alunilite to figure the amount of silicone/catalist to
use.
These are the figures that I used:
Length: 4 31/32" + 1" = 5 31/32"
Width: 1 7/32" + 1" = 2 7/32"
Height: 10/32" = 1" = 1 10/32"
The formula for figuring volume is as follows:
length x width x height
So, the volume on ths mold is:
5 31/32" x 2 7/32" x 1 10/32"
Now, unless you are a genious at multiplying fractions, I
converted the fractional numbers to decimal. 1/32" in
decimal is .03125 so here is what the results are:
31/32" = .96815
7/32" = .21875
10/32" = .3125
This equals 1.4994 cubic inch plus 5" + 2" + 1" for our
volume.
9.4994 cubic inches for our volume. I changed it to
9.499 as my scale only goes to 3 digits to the right of the
decimal point.
According to Aluminlite, their silicone weighs 41 grams per ounce.
So, I needed 389.459 grams of silicone. The mix ratio is 10 to
1 (silicone base to catalyst) I needed 38.945 grams of catalyst.
I use a clear plastic cup to mix larger amounts of silicone. I
placed it on my scale then turned on the scale. Once the scale
zeroed out, I added 389.459 grams of silicone base and the
38.945 grams of catalyst. I used a tongue depressor to mix it up
being careful to mix it slow and to scrape the sides and bottom
regularly to get all of the base mixed. Once the silicone is
thoroughly mixed, I tapped the cup on the top of the workbench to
remove as many of the large and medium bubbles as possible. Then
I poured the silicone mix into the mold box by slowly pouring it
from the center out. Do this SLOWLY so that the silicone gets
into all of the crevices. Once the mixture reaches the top of the
mold box, I gently tap each side of the bold to remove any
air that may have gotten into the mix during the pour. Once that
is done, I used the mold release on the large piece of styrene
and placed it on top of the box and placed weights on it.
I let my mold set for 24-36 hours. After 24 hours I checked it
by gently lifting up on the styrene sheet. If the silicone tried
to stick to the sheet, I left it alone for another 36 hours. The
styrene sheet is used to ensure that the bottom of the mold is
flat to eliminate the problem that occurred when I did it the first
time.
When the silicone has set up (I checked it by using the pads on
my fingers to gently press down on the top of the silicone to
check for "soft" spots. If there are none, then it's ready to
start getting ready to pour the "top" part of the mold. If there
are still some "soft" spots, let it set for another 12 hours.
time to pour the silicone. I used the Rubber to Rubber
mold release to completely coat the inside of the box,
clay and part. This ensures that the silicone does not
bond to anything.
I used the formula listed in the instructions from
Alunilite to figure the amount of silicone/catalist to
use.
These are the figures that I used:
Length: 4 31/32" + 1" = 5 31/32"
Width: 1 7/32" + 1" = 2 7/32"
Height: 10/32" = 1" = 1 10/32"
The formula for figuring volume is as follows:
length x width x height
So, the volume on ths mold is:
5 31/32" x 2 7/32" x 1 10/32"
Now, unless you are a genious at multiplying fractions, I
converted the fractional numbers to decimal. 1/32" in
decimal is .03125 so here is what the results are:
31/32" = .96815
7/32" = .21875
10/32" = .3125
This equals 1.4994 cubic inch plus 5" + 2" + 1" for our
volume.
9.4994 cubic inches for our volume. I changed it to
9.499 as my scale only goes to 3 digits to the right of the
decimal point.
According to Aluminlite, their silicone weighs 41 grams per ounce.
So, I needed 389.459 grams of silicone. The mix ratio is 10 to
1 (silicone base to catalyst) I needed 38.945 grams of catalyst.
I use a clear plastic cup to mix larger amounts of silicone. I
placed it on my scale then turned on the scale. Once the scale
zeroed out, I added 389.459 grams of silicone base and the
38.945 grams of catalyst. I used a tongue depressor to mix it up
being careful to mix it slow and to scrape the sides and bottom
regularly to get all of the base mixed. Once the silicone is
thoroughly mixed, I tapped the cup on the top of the workbench to
remove as many of the large and medium bubbles as possible. Then
I poured the silicone mix into the mold box by slowly pouring it
from the center out. Do this SLOWLY so that the silicone gets
into all of the crevices. Once the mixture reaches the top of the
mold box, I gently tap each side of the bold to remove any
air that may have gotten into the mix during the pour. Once that
is done, I used the mold release on the large piece of styrene
and placed it on top of the box and placed weights on it.
I let my mold set for 24-36 hours. After 24 hours I checked it
by gently lifting up on the styrene sheet. If the silicone tried
to stick to the sheet, I left it alone for another 36 hours. The
styrene sheet is used to ensure that the bottom of the mold is
flat to eliminate the problem that occurred when I did it the first
time.
When the silicone has set up (I checked it by using the pads on
my fingers to gently press down on the top of the silicone to
check for "soft" spots. If there are none, then it's ready to
start getting ready to pour the "top" part of the mold. If there
are still some "soft" spots, let it set for another 12 hours.
