You level the plate, dial in the exposure, and still the first centimetres look washed out or streaky. Nine times out of ten the problem is not your settings — it is the resin sitting in the vat. Pigment settles, volatile components spread unevenly, and a patient, proper mix is the cheapest quality upgrade in LCD printing.
Why a Vat Goes Bad Without Mixing
Resins are suspensions, not solutions. Photoinitiators and pigments settle toward the bottom on the shelf and even inside a sealed bottle between uses. Inside a vat, each cured layer selectively consumes near the surface, leaving the top slightly depleted and the bottom richer — until streaks and translucency show up on the print.
Signs You Are Printing an Unmixed Vat
- Washed-out colours and milky translucency printed as "clear".
- Streaky horizontal bands on an otherwise flat surface.
- Under-exposed rafts near the vat bottom, over-exposed on the top.
- Layer-detail softness that settings tweaks never fully fix.
How to Mix Resin the Right Way
In the Bottle
Before pouring, roll the bottle between your hands for 30–60 seconds (never shake hard). Shaking whips in air that later pops as surface bubbles and voids.
In the Vat
Use a clean silicone spatula to slowly stir the full depth, scraping the bottom corners where pigment hides. On printer models with a built-in mixing paddle, run it for a minute before the first layer.
For large vats, a dedicated heated resin mixer keeps pigment suspended and viscosity low in one pass — a worthwhile tool for frequent resin users.
| Situation | Recommended Mix |
|---|---|
| Fresh bottle, all-new pour | Roll 45s + stir full vat depth |
| Refill from same resin line | Stir 60s, scrape bottom corners |
| Vat rested overnight | Stir 90s before pulling plate up |
| Heavy pigmented / metallic | Mix paddle + spatula, then settle 5 min |
Settling and Trapped Air
After mixing, a short settling pause of 3–5 minutes lets bubble columns rise to the surface. Scoop any persistent foam with a filter before your first exposure. A vat that stays too long unused should be re-mixed rather than trusted — residuals after a weekend can deplete the photoinitiator locally.
Resin Temperature Affects Everything
Cold resin flows thicker, drags on the film, and under-cures. Aiming for a stable vat temperature near 25–30 °C improves flow and detail consistency. The HeatMixer doubles as a gentle heater for exactly this purpose.
Your Mixing Routine, Star to Star
- Roll the bottle 45 seconds before any pour.
- Pour through a filter to keep cured flakes out.
- Stir the full vat depth, scraping the corners.
- Let bubbles rise 3–5 minutes; skim any foam.
- Check resin temperature; warm if under 25 °C.
Try the routine with a straightforward, forgiving ANTINSKY Standard Lite Resin, which is fast to dial in, or a tougher body with ANTINSKY Standard Resin. Consistent mixing removes a whole class of failures no exposure table can fix.