Flash Time / Open Time
Quick answer: Flash time is how long a coating takes to start evaporating solvents and show visual cues like rainbowing; open time is the workable window to level the coating before it begins to set. Many brands use the terms interchangeably.
What it means
After you apply a ceramic coating, solvents begin to flash off and the film starts to react. During the open time, you can level the product cleanly. If you level too early, you can smear or remove too much product; too late and you risk high spots because the film has started to set.
Why it matters
- Finish quality: timing controls whether the film levels to a clear, even gloss or locks in proud patches.
- Process control: guides section size, applicator load and towel rotation for consistent results.
- Environment: temperature, humidity, airflow and panel temperature shorten or lengthen the window.
- Efficiency: predictable timing reduces rework and helps plan inter-coat windows and cure protection.
Where you’ll see it
Manufacturer instructions, training guides and pro forums describing when to level, how big each section should be and how long to keep the car dry after application.
Context
Car Paint Protection; Ceramic coatings
Common mistakes
- Working areas that are too large for the conditions, so parts of the section have already set before levelling.
- Trying to compensate by laying product too thick to “buy time”, which increases the risk of high spots and streaks.
- Ignoring panel temperature, draughts or direct sun which shorten the window dramatically.
- Levelling without raking light, so you miss overlaps and edges as the window closes.
- Stacking coats outside the inter-coat window so the second layer cannot bond properly.
Written by Danny Argent. Last updated 06/11/2025 17:40