Green stuff working time is the sculpting window, not full cure: the two sources state different minutes, so plan small batches and check workability before trusting any timing.
The short answer
Working time is the window in which a mixed batch still suits the sculpting job in front of you: soft enough to push, roll and reposition for the shape you are building. It is not the same as full cure. The Army Painter's listing and the Kneadatite guide state different numbers for that window, and this article does not claim to explain why; treat each figure as a bounded source statement, not a rule for every batch. Your own conditions sit between those pages and your bench.
Workability, shape holding and full cure are three states
A mixed batch moves through three stages:
- Workable: soft and tacky, so you can push, roll and reposition it for the task at hand.
- Shape holding: firm enough to keep the form you gave it, but not a finished part.
- Fully cured: hard enough for sanding, shaving or priming on the maker's terms.
Plan the session around the workable window. Shape holding is not permission to prime or paint, and it does not settle whether parts get painted before they are assembled; that assembly question is decided separately from this clock. A part that feels hard is not proof of full cure.
What each source actually states
Source and stated conditions | Working time | Next stated stage | Full cure or hardness |
|---|---|---|---|
The Army Painter TL5037P listing for the original Kneadatite Green Stuff | 20-30 minutes, described as a flexible working time | After 8 hours it should be fully dry and can be sanded and shaved | The page's how-to text states the putty completely cures within 24 hours |
Sylmasta's Kneadatite guide for a 50-50 mix, dependent on mixing ratio and temperature | 90 minutes to 2 hours | Curing stage after 4 to 5 hours | Maximum hardness 20 to 24 hours after mixing |
The Army Painter's TL5037P listing states 20 to 30 minutes of flexible working time, fully dry and sandable after 8 hours, and complete cure within 24 hours. Sylmasta's Kneadatite guide, for a 50-50 mix, states 90 minutes to 2 hours of workability, a curing stage at 4 to 5 hours, and maximum hardness at 20 to 24 hours, depending on mixing ratio and temperature. These are separate published statements made under different conditions, not a measured comparison; averaging them would invent a number neither source supports. Neither page gives a universal ready-to-prime deadline, so do not borrow one.
Plan the session around the window
- Mix the smallest batch that covers the job, following the package label, and split larger jobs into separate batches rather than rushing one mix.
- Record when you start mixing and when the two parts are fully blended, and follow the product's own definition of when the clock starts; the curing reaction is not deferred until you finish kneading.
- Press a scrap from the batch before committing it to the model; once the mix no longer suits the job in front of you, that was your working time.
- Shape the piece first, then leave it to reach the stated cure stage.
- Keep a scrap from the same mix in the same room as a handling reference; how it feels is not a cure check.
- If a batch later refuses to set, this related article on Milliput not hardening covers a separate Milliput problem, not a Green Stuff manufacturer's diagnosis; its curing instructions are not interchangeable with Green Stuff. Use it as a general cross-check on mix, curing window and storage history before refilling or repainting.
Keep a blank record
Fill this in only as you work, and leave it empty until then.
Batch | Mix started | Blend complete | Workable for | Shape held at | Next check |
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Handle it safely
Wear gloves, avoid skin contact and keep the putty away from your mouth; do not lick fingers or tools to smooth it. The Army Painter listing carries skin, eye and dust warnings, so follow the product safety label and control dust if you sand cured material. Do not sand putty before it is cured. Use only the mixing method the package describes, follow its SDS, and if it and either guide disagree, follow the package and ask the supplier.
Avoid these shortcuts
Do not stretch the window by changing the mix ratio, heating or chilling the putty, or blending it with another putty, and do not add saliva, oil or water to the mix. None of that is supported here, and none of it is a safety claim about the product.
