Best time to spray

C

Chris Martin

Promoted Users
Hello SPI Friends,

As I mentioned in previous postings, I am working on becoming proficient enough on spraying white Single Stage to paint my beloved home built airplane. Has not been an easy quest but I think I am getting there. Yes, my goal is to produce a very nice finish Worthy of an SPI paint.

This forum has become my daily read and Barry, as well as some other experienced painters in the forum, have been of invaluable help. But I am not quite happy with my skill level yet so I will be asking a few questions that may seem trivial to an expert but not so much to an amateur.

My question today is: Which is better, to spray in the morning at 80F and 93%(higher) humidity or in the evening at 90F and humidity below 85%(lower)? I would like to spray during both times but I have been spraying test pieces at high temperatures with inconsistent results (mid 90s and higher and low (or lower for Florida standards) humidities during the mid part of the day) and I was told to stop and only spray when temps are lower. My problems are mostly orange peel and nibs that I am starting to suspect are not dust or air supply contamination (But that will be a subject of another posting)

My question is to understand what has a more detrimental effect on the quality of my spray. Is it temperature or humidity? I am using white SS with slowest everything. I just ordered some Retarder and it is something I will be experimenting with next week.

Every little thing that helps will make me improve.

Best,
Chris
 
Thanks for the feedback guys. Morning is certainly nice. The only drawback for me is that by 9 I have to be sitting in my desk at my “other“ job but it’s here at home :) I can wake up early so no biggie. But if the high (very here in FL) humidity is not as much an issue as the temps then it is better.

Do keep in mind that I have a well sealed DIY spray booth (at times I do think though that the garage may have been better) so bugs may be manageable except when I open the booth doors. But great point.

Thanks
Chris
 
Very high humidity can actually affect how the clear lays out. Compensate by using the slowest reducer and activator possible and using some of the SPI retarder in your clear.
 
Thanks Chris. I ordered some retarder last week to give that a try. Read a lot about it and curious to see how that works.
 
Shine, it’s true that the humidity starts to rise in the evening but it peaks in the morning. About 10% difference 83-93% tomorrow as an example) I’ll go for the morning to follow the advice and I think the process will be much more enjoyable. Once I get to the larger parts (wings and fuselage) I’ll plan for spraying on weekend mornings to have more time just in case.
 
If humidity is the problem then keep in mind that its relative humidity. Its relative to the current temperature, so just because the humidity is high in the morning, doesn't mean it will be high when it warms up. Its determined by the dew point. Maybe the Scientist will shed some light on the subject.
 
Relative humidity decreases as temperature increases for a given dew point.

Not a real scientist, I am an applied scientist…. :D

Don
 
my shop will be 105 or better today. it will still be miserable at 6am. if i could leave it open it would be better.
i'm plumbing in my a/c this fall when they have time. but my days of painting are over except for the bikes and maybe some small thing.
i just look at hourly and pick the best time.
 
shine said:
my shop will be 105 or better today. it will still be miserable at 6am. if i could leave it open it would be better.
i'm plumbing in my a/c this fall when they have time. but my days of painting are over except for the bikes and maybe some small thing.
i just look at hourly and pick the best time.
Click to expand...
Yes. It was 101 the past couple days inside the shop. I sprayed 2k high build and it was drying as it was landing...just can't do anything
 
Have shop heater on so paint will cure

Screenshot_20230619-143520_Weather.jpg
 

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i will shoot at 6am tomorrow. coolest part of the day. dont have much to do. be done by 8 or so.
in my younger years i did not work july/aug. took off and stayed in the water . shooting lacquer at 100+ just didn't work.
 
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