One of the most common tech questions we get at BJB is
Which mold release do I use for my project
It can be confusing due to the number of options out there
But let's break it down and simplify the process
BJB offers a selection of aerosol spray releases
As well as paste wax and our Challenge 95 liquid wax
We even have bulk versions of certain releases for large scale production
For releasing cast urethanes from silicone molds
We typically use the E236 Urethane Release
Or the E302 Rocket Release
The difference between the two is this
E236 Urethane Release is silicone based
which gives the most amount of release
helps prevent silicone molds from drying out prematurely by acting like a mold conditioner
The downside to using this release is that those silicone oils can be transferred to
the demolded part
making painting or bonding to the part very difficult
Rocket Release is non-silicone based
uses soy-based lecithin oil
It's often referred to as a paintable mold release
because it easily washes off the demolded parts
with warm soapy water without leaving a residue you may not get as many parts out of a mold
with it but if you need to paint or bond your parts
it's still a great option for a variety of cast parts
also worth noting the urethane release tends to leave a shinier
surface on the demolded parts while the Rocket Release can leave a slightly
less shiny surface not a big deal if you're going to paint them
or the parts have a low gloss surface to start with
for releasing Silicone from Silicone
we like Zip Release
Zip is basically Vaseline in a spray can It works well with both Tin and Platinum silicones
It's important to use the right release when making two part molds
or you can end up with a disaster
If you mistakenly use something like E236 Urethane release you basically just sprayed silicone primer
on it and would fuse the two halves together
For rigid tools like fiberglass
Machined aluminum or even 3D printed tools
it's often best to go with a double layer of release approach
because they tend to be more difficult to get the parts out of
Think of it like applying a sealer and then a spray release on top of that
If your surface is smooth and shiny we like to apply a paste wax and buff 2-3 coats on and off
Karate kid style wax on, wax off
If you r mold is highly textured or has difficult geometry
our Challenge 95 liquid wax makes life easy it simply wipes in using a cloth or brush
allowing dry time in between each coat once you've wax the surface apply your spray release of choice
For expanding foams like our PolySoft flex foams
or parts that need painting Rocket Release is a good option
we avoid using E236 Urethane release with foam because the silicone oil can cause issues
with the skin quality you typically only need to do the wax sealer
once or twice on new molds prior to applying spray release
once the mold is seasoned you can simply apply a spray release in between part castings
and to give you one more tip on mold releases sometimes getting flex foams out of silicone
molds or even rigid molds with a uniform skin can be a challenge
as mentioned in our video about making 3D printed molds
using talc powder in addition to the rocket release
can improve demolding and even improve the skin quality of the foam
dust in an even coat of talc and tap out an excess
and you'll be amazed at how easy the parts release from the tool
if you have any questions on mold release please feel free to let us know in the comments below
as always, BJB is here to help take some of
the mystery of materials so don't hesitate to contact us
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