Wet on wet, and the client only sees the last coat
A wall is finished in three coats that get thinner as they get more visible. The one everyone judges is the easiest to redo and the smallest number on the card.
Three coat depths listed down the left — scratch, float, set — getting smaller as they go. A ratio, 1:3, painted large in the middle. Underneath, fast and handwritten: wet on wet.
The coat a client will ever run a hand over is the thinnest one on the card, and the least of the work.
Why three coats and not one?
Because each layer is doing a different job, and none of them can do another's.
The scratch coat, at 11mm, is the one that actually bonds to the wall and gives everything else something to grip — it's called that because it's raked before it sets, so the next coat has a key to hold onto. The float coat, at 8mm, brings the surface true and flat. The set coat, at 2mm, is pure finish: no structural job at all, just the last few tenths of a millimetre a hand will ever touch.
What does "wet on wet" mean?
That the next coat goes on before the last one has fully given up its moisture.
Plaster that dries hard between coats won't bond properly to what comes after — the surfaces need to still be working together chemically, not just sitting stacked. It's a timing judgement rather than a fixed wait: too soon and the coat below can't support the one above, too late and the bond is weak. The card doesn't give a number for it because there isn't a clean one; there's a hand pressed flat against the wall, checking.
What does the ratio actually control?
How much the material shrinks as it dries.
1:3 is one part binder to three parts sand or aggregate, and it's the base most float coats are built from — richer mixes crack more as they cure, leaner ones are weaker and chalk. The ratio is chosen for the coat it's going into and the wall behind it, which is why a good card states it rather than leaving it to be remembered.
What makes a good mix card?
One that survives being read weeks after the job.
The three depths, the ratio for each coat, and a note on timing that a person who wasn't on site that day can still act on. The handwriting matters as much as the numbers — a card that's purely typed loses the part where somebody wrote "wet on wet" fast, in the middle of a job, because it mattered enough to stop and note down.
Does a mix card belong to a particular plasterer or firm?
A card can, freely. The ratio and the coat depths can't.
1:3 and a three-coat build-up aren't anybody's invention — they're how the material behaves, the same way a diagram of a two-way lighting circuit is a fact about wiring rather than a design. A specific firm's job-card layout or letterhead is theirs to licence if a real one is the point; otherwise the invented card is the better one, because it can carry the wearer's own job rather than somebody else's client.
Does this apply to other trades that build up in layers?
Most trades with a hidden substrate and a visible finish work the same way.
A roof gets its waterproofing from geometry and depth rather than any single layer — a thatcher's course diagram makes the same argument from the outside in rather than the inside out. Painting and decorating, screeding and rendering all share the shape: the coat that's judged is rarely the coat that's doing the structural work.
What's the strongest objection to putting this on a shirt?
That it looks like a spec sheet, not a design.
It reads that way at a glance and then doesn't, once the numbers get smaller as they go — that's a shape, not just a list, and it's the shape of the whole job compressed into three lines. The ratio sitting large in the middle gives it a centre the way a logo would, without being one.
Does it print well?
Yes, with one condition: the texture has to stay coarse.
Real plaster cracking is fine detail that falls below the weave's floor if it's reproduced at true resolution, so the cracked surface on this hero is drawn deliberately coarser and sparser than a photograph of one would be. The numerals want to stay flat and dark — charcoal works well against sand — with the one blue reserved for the ratio, so it reads first.
How do I get one made?
Describe your card at JustOG — the coat depths, the ratio, and what the handwritten note should say. Pick a direction, drag the crop frame, see it composited on the real garment, and it's made to order and shipped.
Designs other people have published are in the shop.
Eleven millimetres nobody will ever touch, under two that everybody will.