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fan on or off while final coat sets up?5/13
we have an enclosed automotive booth and are spraying 2k poly.
it was cool and humid yesterday so i thinned the material pretty heavily. i sprayed two large pieces - the back of one and the front of another. everything was from the same mix of finish. i sprayed the back first and left the fan on after i was done finishing. the quality of the back is unimportant and i was in a hurry to spray the other piece. this piece dried perfectly, without any bubbles, dirt, etc. to be found. this piece was natural sapele.
for the other piece, i turned the fan off immediately after spraying and let it dry without any airflow across the surface. this piece dried with some small bubbles, that i was able to hit with brown paper 18 hours later to bring the finish to an acceptable level. this piece was stained walnut.
i always though airflow could do more harm than good, but yesterday's results showed the opposite of this.
I leave the fan on low to continue to carry out the solvents as they flash off and to keep anything from landing on the finish. Once it tacks up, then I turn it off.
we don't have a speed control on our fan so all on or all off.
i usually turn the fan on once it has skinned over. is there anything that can happen to the finish after it has skinned over (30-1 hour after being shot)?
I believe air flow is crucial to any finish curing. I currently have a box fan set on low blowing across what I sprayed today. Yes, I leave the booth on all day long.
Were both pieces the same ? If I understand your post correctly ,one was sapele ,the other was walnut with stain, could it be an issue with the stain . Maybe the thinned down finish reacting with the stain ?I'm just trying to eliminate any differences to make sure your comparing apples to apples.
Aren't small bubbles called solvent pop and are the result of too thick a coat? Less airflow would help this situation not hurt it.