Most pages about release agents describe chemistry. This one describes the decision — what the product actually does inside the die, why the cheapest drum is often the most expensive per 1,000 shots, and how to run a trial that produces a number you can defend in a meeting.
A release agent is sprayed onto the open die face between shots. It does two jobs that pull in different directions. The first is separation: it leaves a film that stops molten metal welding to the steel. The second is cooling: the water in a water-based product evaporates on contact and pulls heat out of the die surface, which would otherwise see repeated thermal shock at the temperatures involved in aluminium casting — up to roughly 500 °C at the surface on the die side.
The tension is that the film has to be strong enough to release the part and thin enough to disappear before the next process. A product that releases beautifully and leaves a silicone film on the casting has moved the cost downstream to the plating line, where it shows up as blisters and rework that nobody attributes to the die spray.
This is the first decision, and it is decided by your downstream process — not by preference.
| Family | What it does well | Where it hurts | Choose it when |
|---|---|---|---|
| Water-based, silicone-free | Cools the die, low residue, compatible with plating and painting | Needs tighter dilution control and better water quality | Any part that will be plated, painted or anodised; high-volume automated cells |
| Water-based, with silicone | Very strong release on difficult geometry, forgiving on dilution | Silicone carry-over into downstream surface treatment | Parts that go straight to assembly or machining, no coating step |
| Oil-based | Excellent lubricity and high-temperature film stability | More smoke, more residue, harder to clean off | Heavy sections and very hot dies where lubricity outranks cleanliness |
| Powder / wax | Long dwell, no water to flash off | Not suited to automated spray cycles | Special cases, low-volume or manual operations |
The families above are the general industry classification. Which one we would quote you depends on your alloy, part and downstream process — that is what the sample and trial are for.
Release agent is bought by the kilogram and used by the litre of working liquid. That gap is where suppliers compete, because a concentrate that dilutes further looks cheaper on a price list even when it performs worse.
Two numbers decide the real cost:
The comparison that survives scrutiny is cost per 1,000 shots:
There is a discipline question inside that formula. A supplier can always publish a more generous ratio than the factory has confirmed, and it costs them nothing until your parts start sticking. We publish the conservative number and confirm the rest during the trial, because an over-optimistic ratio costs the customer more than it saves us.
The cost calculator applies this formula with your figures.
Most failed trials fail for the same reason: two variables changed at once.
Our sample programme ships with a written trial protocol so both sides record the same four numbers. The sample itself is free; each side covers one leg of the freight.
Sticking is visible. Silicone contamination is not. It leaves the foundry as a good casting and arrives at the plating or anodising line as a bad one, and by then it has been through degreasing, maybe blasting, maybe a machining step — so the foundry gets blamed for something it cannot see.
The mechanism is documented in surface-treatment practice: silicone migrates into the surface micro-porosity at die temperature, standard acid pre-treatment does not fully remove it, and the residue then acts as an insulating layer that inhibits coating growth or adhesion. The visible result is blistering, peeling, or white spots across the part.
The fix is upstream. If a casting is going to a plating, painting or anodising line, the release agent for that part should be formulated without silicone from the start — not tested and hoped for. More on silicone-free grades and the 2026 EU siloxane restriction →
Grades and confirmed dilution ranges for aluminium, magnesium and zinc, from 280 to 3,200 t.
Deep-cavity housings, new-energy structural parts, 3C thin-wall, electroplated sanitary ware.
Compare your current brand and ours on cost per 1,000 shots, using your own invoice price.
European Commission. “Commission Regulation (EU) 2024/1328 of 16 May 2024 Amending Annex XVII to Regulation (EC)
No 1907/2006 … as Regards Octamethylcyclotetrasiloxane (D4), Decamethylcyclopentasiloxane (D5) and
Dodecamethylcyclohexasiloxane (D6).” Official Journal of the European Union, 17 May 2024.
ELI: reg/2024/1328/oj; CELEX: 32024R1328.
“Releasing, Cooling and Protecting — The Significance of Release Agents for Die Casting Technology.”
EUROGUSS, 2019.
“Anodizing Aluminium Process: A Complete Guide for Die Casting Parts.” Inox Casting.
The questions buyers actually ask before the first drum. Answered without marketing language.
A die casting release agent is a liquid sprayed onto the die face between shots. It does two jobs at once: it forms a film that stops molten metal from welding to the steel, and the water in it cools the die surface so the next shot does not overheat the tool. The film has to release the part and then get out of the way — a release agent that stays on the casting becomes a defect at the plating or painting stage.
For most aluminium, magnesium and zinc casting, water-based is the default: it cools the die, it is dilute enough to be economic, and it leaves little residue for the next process. Oil-based grades still have a place where lubricity and very high die temperature matter more than cleanliness. The choice depends on your downstream process, not on a preference.
The ratio depends on the alloy, the wall thickness, the cavity depth and the die temperature. A published range is a starting point, not a specification — the trial on your machine fixes the final value. On our own grades the factory-confirmed starting ranges are 1:120–200 for the aluminium workhorse ZP-418, 1:80–100 for the magnesium workhorse ZP-801, and 1:100 for the zinc workhorse ZP-118.
Compare cost per 1,000 shots, not price per kilogram. Cost per 1,000 shots = price per kg × spray volume per shot ÷ dilution ratio. A cheaper drum with a weaker dilution can cost more per 1,000 shots, and a price list will never show you that.
Silicone left on the casting surface is the usual cause. At die temperature the siloxane can migrate into the surface micro-porosity, and standard acid pre-treatment does not fully remove it. The residue then acts as an insulating layer, so the plated or anodised coating blisters, peels or shows white spots. The fix is upstream: use a grade formulated without silicone for any part that will be plated, painted or anodised.
When the residue starts changing the part, not on a fixed calendar. In practice that means watching three signals: sticking that needs a higher spray volume, surface marks on the casting, and a rising scrap rate at the same settings. A customer of ours measured their die cleaning interval moving from 7 to 21 days after switching grade on deep-cavity automotive housings — measured by them, not by us.