PVA vs Wax vs Semi-Permanent Mold Release: Which One for Your Mold
08 October 2026
Which release goes on a mold comes down to two questions: how many parts has this tool pulled, and can you afford to lose this one? A new mold, a repaired mold, a plug you are pulling a mold off of, or a one-off part you cannot remake: paste wax with a PVA film over it. A seasoned production mold that has pulled its first dozen parts clean: wax alone, one coat per pull. Casting urethane, epoxy or concrete out of a rubber mold: a silicone spray. That is the whole PVA vs wax mold release argument; the rest is how each one goes on.
Paste wax: the base layer of every system
Every release system starts with wax, because wax seals the tool surface and fills the micro-porosity a fresh tooling gelcoat still has. Rexco's directions for Partall #2 apply to any paste wax: wipe on a thin coat, start buffing about one minute later before it gets hard to polish, and buff to full gloss. A new or reconditioned mold gets 3 to 4 coats, each buffed out before the next, then at least an hour after the last coat before PVA or layup. A seasoned mold gets one coat, buffed, before each pull.
What wax alone will not do is save a green tool. A mold that has just cured is still giving off styrene and still has open porosity, and polyester can bond right through three coats of wax on it. The first several pulls off a new tool get wax and PVA; once parts are popping clean and the surface has a hard shine, drop the PVA. Formula Five is the wax most production shops run at that stage; Partall #2 is the general-purpose wax and the standard prime coat under Partall PVA.
PVA: the film that makes the part let go no matter what
Polyvinyl alcohol is a water-soluble film sprayed or wiped over the waxed mold. The resin cures against the film, and after the pull it peels off the part or washes off with warm water. With PVA on the tool a stuck part is close to impossible. The cost is finish: PVA leaves a faint texture, so a gelcoated part pulled over it needs a wet sand and polish, and a part that has to come off glass-smooth is a wax-only part on a mold you trust.
We carry two Partall films and they are different chemistries. Partall #10 is the alcohol-based green film: mist coats flash in 10 to 15 minutes, a flow coat dries in 30 to 45, and it is flammable, with a flash point around 76°F (24°C). Partall Coverall Film is the water-based purple film: non-flammable, applied by spray, brush or sponge, and slower to dry; read the label for the wait at your humidity. #10 is what most fiberglass shops keep because it lays down fast; Coverall is for a shop that cannot have a flammable solvent in the room. Either one goes over wax, never under it, and never over a silicone release.
Silicone spray: the release for casting molds
Pol-Ease 2300 is a blend of silicone oils and resins in an aerosol, made for releasing polyurethane rubber and plastic, epoxy, waxes and concrete from urethane molds and sealed patterns, and its film gives multiple pulls per application instead of a wax coat you rebuild every time. It is the right choice for a rubber mold you are casting parts out of, and the wrong choice on a fiberglass mold whose parts get painted or gelcoated afterward, because silicone shows up as fisheyes in any coating that follows. It also inhibits liquid silicone, so keep it away from silicone mold making. The solvent-based semi-permanents that bond to the tool and run dozens of pulls are a production tool; if you pull parts by the hundred you are already on one.
Spec table
| Release | Apply | Wait before use | Pulls per application | Part surface | Use it on |
|---|---|---|---|---|---|
| Partall #2 or Formula Five paste wax | Thin coat, buff at about 1 minute; 3 to 4 coats new, 1 per pull after | 1 hour after the final coat | 1 | Gloss, as molded | Every fiberglass and carbon mold |
| Partall #10 PVA | 2 to 3 mist coats then a flow coat, over wax | 10 to 15 min per mist coat, 30 to 45 min flow coat | 1 | Slight texture, wet sand to restore gloss | New molds, plugs, repaired tools, one-off parts |
| Partall Coverall Film PVA | Spray, brush or sponge, over wax | Longer than #10; see the label | 1 | Slight texture | Same jobs where a flammable solvent is not allowed |
| Pol-Ease 2300 | Spray, brush out | See the can | Multiple | Silicone residue; wash before any coating | Urethane rubber molds, castings, sealed patterns |
Which one, by tool
A new fiberglass mold, or one you have just repaired: 3 to 4 coats of Partall #2 Paste Wax - Mold Release Wax for Fiberglass & Composite Molds, an hour to breathe, then PVA Mold Release - Partall # 10 in mist coats and a flow coat for the first several pulls. Same job with no solvent allowed: Partall Coverall Film PVA Mold Release over the same wax. A production mold pulling clean: Formula Five Mold Release Wax, one buffed coat per pull, no PVA, so the parts keep their gloss. Casting urethane or epoxy parts out of a rubber mold: Pol-Ease 2300 Mold Release Spray. Partall #10 and the styrene that follows both want a fitted P100 with organic vapor cartridges, nitrile gloves and eye protection.
Frequently asked questions
Do I need PVA over mold release wax?
On a new mold, a repaired mold, a plug, or any part you cannot afford to lose: yes. Wax alone can let polyester bond through it on a green tool. Once the mold has pulled its first several parts clean, drop the PVA and run one buffed coat of wax per pull. Wax first, 3 to 4 coats on a fresh tool; PVA always goes over the wax.
How many coats of mold release wax on a new mold?
Three to four thin coats of Partall #2 or Formula Five, each wiped on with a clean rag, buffed starting about one minute after application, and polished to full gloss before the next. Wait at least an hour after the last coat before PVA or layup. On a seasoned production mold, one buffed coat per pull; more just builds wax that ends up in the part.
Can PVA mold release be used without wax?
It can be sprayed on bare gelcoat and it will release, but with no sealed surface under it the film beads on porosity and tears on demold, and any pinhole is a stuck spot. Wax first, 3 to 4 coats on a new tool, then PVA. Partall #2 is formulated as the prime coat under Partall #10 and Coverall; they are designed as a pair.
What is the difference between Partall #10 and Coverall Film?
Solvent. Partall #10 is alcohol-based, green, flammable with a flash point near 76°F, and fast: mist coats flash in 10 to 15 minutes, a flow coat in 30 to 45. Coverall Film is water-based, purple, non-flammable and slower to dry. Both go over wax and wash off with water. Pick #10 for speed in a ventilated shop, Coverall when no flammable solvent is allowed.
Will silicone mold release ruin gelcoat or paint?
On the part, yes, if a coating follows. Silicone left on a surface causes fisheyes in gelcoat, paint and clear coat, and it is hard to wash off. Keep Pol-Ease 2300 for urethane and casting molds where the part is finished as it comes out, run wax with PVA on fiberglass molds whose parts get coated, and never spray silicone near an open gelcoat job.
What You Need For This Job
- Partall #2 Paste Wax - Mold Release Wax for Fiberglass & Composite Molds: the base coat on any new or general-purpose mold, 3 to 4 coats
- Formula Five Mold Release Wax: one coat per pull on a seasoned production mold
- PVA Mold Release - Partall # 10: fast alcohol-based film over wax for new tools and one-off parts
- Partall Coverall Film PVA Mold Release: water-based, non-flammable PVA for solvent-free shops
- Pol-Ease 2300 Mold Release Spray: silicone release for urethane casting molds and sealed patterns
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