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Rough Finnish Rustseal


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Bought a tin of Iron red Rustseal + cleaner and rust blast today to coat an engine block, painted it on and left it to dry, came back a few hours later to find it had dried and gone all rough, luckily i could just peel it off 


Block had been chemically cleaned then washed with detergent then aquaclean then treated with rustblast (as per instructions on bottle) 


Whats going on ?

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It sounds like you applied the RustSeal very thick which will cause the bubbling issues.  Please sand the surface down and apply two thin covering coats.


Small bubbles in or on the paint film.


Liquid solvent (thinners/reducers) becomes "trapped" in the paint film when the surface layer skins over too quickly, preventing their evaporation into the atmosphere. Solvents that vaporize within the paint film leave bubbles, pinholes or craters as they push through and "pop" the surface. Solvents can be trapped due to:

Thinner/reducer evaporating too fast for spraying conditions.

Inadequate flash time between coats.

Excessive film thickness or "piling on" of heavy/wet coats.

Too hot and/or too humid conditions.

Too much air movement causing coating film surface to "skin over" before solvents evaporate.

Excessive purge/flash time before force drying.


Sand smooth with 320 or finer grit sand paper, and recoat.


Apply THIN COVERING coats.

Avoid allowing coating to puddle/pool in low areas.

Allow each coat to dry to the touch (no longer sticky or tacky) before applying subsequent coats.

Use correct solvent for proper evaporation rate.

Avoid too hot/humid atmospheric conditions (ideal = 55°-82°F/13°-28°C)

Maintain correct spray gun speed & distance.

Use the recommended air pressure.

Use the correct air cap/nozzle/needle recommended.

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