Size & Adhesive Dry-Time Calculator
Pick your size type and room conditions to get a working estimate of tack time and how long the surface stays receptive to leaf.
Estimated tack & open time
How the estimate is built
Each size type has a typical tack time and open window at a 70°F, 50% relative-humidity reference room. From there, every degree above 70°F speeds drying by roughly 1%, and every degree below it slows drying by about the same amount; every point of humidity above 50% RH slows drying by roughly 1%, and every point below it speeds it up. The two effects multiply together, so a warm, dry room and a cool, damp one can produce noticeably different times from the same size.
These are planning figures, not a chemistry lab result — humidity meters, thermometers, and manufacturers themselves will tell you more than a rule of thumb ever can. Use the estimate to plan your session, then confirm with the touch test before you lay leaf.
Frequently Asked Questions
What does "tack" mean for a gilding size?
Size needs to dry from wet to just tacky — no longer sticky to the touch of a dry knuckle, but still receptive enough to grab leaf. Laying leaf too early smears the size through it; waiting too long past the open window and the size skins over and won't hold the leaf at all.
What's the difference between quick and slow size?
Quick size (often a 3-hour oil size, or a fast acrylic/water-based size) tacks up in a few hours and has a shorter open window, which suits a single work session. Slow size (a 12–24 hour oil size) takes much longer to tack but stays workable for a long time afterward, which is useful for large or highly detailed pieces gilded over several sessions.
Why do temperature and humidity matter so much?
Size dries by solvent evaporation (oil size) or by water evaporation and coalescing (acrylic size), and both processes speed up in a warm, dry room and slow down in a cool, damp one. A size that tacks in 3 hours at 70°F can easily take 4 or more in a cold, humid workshop.
How should I actually check if the size is ready?
Numbers are a starting point, not a substitute for the touch test: press a dry knuckle lightly against the size every 30–60 minutes as your estimated tack time approaches. It's ready when it feels tacky like the back of tape, not wet and not dry.
Educational tool only — a working estimate, not a substitute for your product’s own instructions or the touch test. Always test on a scrap piece first and work in a ventilated space.