Mould Release Spray: Silicone vs Non-Silicone, and When to Use Each
A decision guide for injection, rubber and die-casting moulds, and what to do about oil and wax.
In short
01Silicone release for general moulding with no later finishing; non-silicone when parts are painted, printed, glued or transparent.
02Trial a part through your full finishing process before switching a line to a new release.
03Anti-corrosive storage wax is not a release agent, and release agents are not storage protection.
04Clean the mould before switching release type, and never over-apply.
Use a silicone mould release spray for general moulding of parts that will not be painted, printed or glued, because it gives multiple releases per coat. Use a non-silicone mould release agent when parts will be finished later or are transparent, because silicone residue can interfere with paint, print and bonding, and can mark clear parts.
Why parts stick in the mould
Before blaming the release agent, check the cause. Common reasons a part sticks:
The release film is missing or has worn off.
Undercuts or too little draft in the mould design.
A scratched mould surface, or a build-up of old release and residue.
Mould temperature or cooling time not right for the material.
A release agent fixes the first one. The others need cleaning, process adjustment or toolroom work. See plastic part sticking to the mould.
Silicone vs non-silicone: the decision
Your situation
Choose
Example
General moulding of PVC, ABS, PP or nylon, no later finishing
On SKU 1100: it is listed for injection, compression and vacuum-forming moulds, PVC, ABS, PP and nylon parts, rubber, PU and foam moulding, and gives multiple release cycles per application.
On SKU 1110: it is non-silicone and described as crystal clear and non-staining, with grades listed for polycarbonate, acrylic, nylon, PP, HDPE and ABS. Its page does not state paint, print or plating compatibility, so run a trial part through your full finishing process before switching a line. For clear parts, confirm the correct resin grade with us before ordering; see haze on clear PC / acrylic parts.
Rubber and PU parts
Rubber and PU foam stick when the release film wears out or compound builds up on the tool. Silicone release suits PU foam and potting; if a rubber part must be bonded or painted afterwards, use non-silicone and trial it. See rubber or PU parts sticking.
Mould release oil and wax: where they fit
Mould release wax is widely used in FRP and composite work and resin casting. These are specialised; tell us the resin and the mould material and we will point you in the right direction rather than guess.
Anti-corrosive wax for storage is not a release agent.Mould Saver (SKU 1201) is a wax film to protect stored moulds from rust, especially in monsoon humidity. Do not rely on release agents for storage protection either.
Oil smeared by hand gives an uneven film that can transfer to parts and burn onto hot tools. A sprayed release gives a thinner, more even coat.
Keep the mould clean
Release builds up over many cycles and can cause marks and sticking of its own. Before switching from silicone to non-silicone, or before storage, clean the tool. Mould Cleaner (SKU 1220) is listed to remove grease, silicones, waxes, release agents and light carbon. See mould residue build-up.
Do not over-apply release. Excess transfers to parts and causes the very marks you are trying to avoid.
Safety: release agents and mould cleaners are pressurised aerosols; treat solvent cleaners as flammable until the SDS says otherwise. Use ventilation, keep away from sparks, flames and hot surfaces, and follow the label and SDS. Keep silicone sprays away from paint and print areas.
When to ask an expert
Parts still stick with a fresh release film, or tear and deform on ejection: likely draft, mould design or temperature, for a toolroom or process engineer.
Optical, medical or display-grade clear parts.
Heavy carbon or burnt polymer that solvent will not move.
Tell us the material, the mould type and what happens to the part after moulding.
FAQ
Which mould release spray is best for injection moulding?
For general PVC, ABS, PP or nylon parts with no later finishing, a silicone release. For parts that will be painted, printed or glued, or clear parts, a non-silicone release.
Is silicone mould release agent paintable?
We do not recommend painting or printing parts made with silicone release. Use non-silicone and trial a part through finishing first.
Can I use oil as a mould release?
It is uneven and can mark parts or burn on hot tools. A sprayed release agent gives a thinner, more controlled film.
What is mould release wax used for?
Mainly FRP, composite and resin casting work. Anti-corrosive wax such as Mould Saver is a different product, for rust protection in storage.