Humidity monitors

dhutton01

Backyard Hack
I am curious if anyone else makes use of a humidity monitor in their booth/shop. I have two monitors, one indoor and one outdoor. I make my decisions on how high to heat my shop based on humidity. When the weather is damp/humid and humidity higher than 50% I heat my shop warm enough to force the humidity to 50% or lower. Quite often this means significantly warmer than the 65/70 degrees specified for spraying and curing paint. I feel this guarantees proper drying/flashing of cleaners and avoiding issues with moisture when spraying.

Anyone else track humidity when working in their shop?

I am guessing scientists like Lizer might also use dew point in their analysis and decision making. :)

Don
 
I know when it's high humidity clear doesn't want to lay out as well. Temps don't seem to matter either, whether it's 68 or 90+ degrees. If it's humid it's hard to get clear to lay down nicely. It's a noticeable difference compared to lower humidity days. I think what you are doing is very sound Don. :)
 
I sometimes heat my shop to 80 degrees if it’s cool and humid outside. I feel it gives me a better result. Just call me Mister Jamaica. :D

Don
 
I have a sensor that links to a digital display on my work bench along with one in the house. It tells me temp and humidity. I have one outside also so i can see everything front my kitchen. That way i know if there is an issue with my heater.


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Don I’m a microbiologist not a meteorologist! And at work I have a dry room that maintains humidity at 20% for our moisture sensitive tests and it’s the facilities guys that make all that magic happen. Now as a hay farmer, the humidity is something I monitor every day in the summer. However it’s God who’s controlling that one. That said, here in SW MI humidity is pretty low and not something I have to worry about too often. 40-50% in the summer typically. Occasionally will get a few days in the 60% and just a few high humidity days. And I don’t have the luxury of spraying in the winter.
 
Yes, I pay close attention now to: relative humidity levels at temperatures outside where I intend to spray--if I pull air from outside, barometric pressure and what temperature dewpoint is for outside temps and what they are likely to be after all the fun is to be done. I use a handheld moisture meter operated by batteries and a similar Fluke temperature probe with several thermocouple taps and a dial Airguide barometer. It has helped a lot in making better guesses to estimate how good or poor my work might end up being and how to adjust. Airflow volume increases in the booth or paint room/garage may need to increase.

Reported humidity values are only relative (RH) to the maximum amount the air can hold at that temperature and not coming out as rain or fog. The actual grains or grams or whatever weight measurement of water vapor in say a cubic foot of air remains the same unless it is condensed out, or stripped off by desiccant etc....The little HVLP TURBINE things everyone loves to bash can with some tweaking be made to work well for some automotive refinish products--but when I measured the air coming out the air hose of mine at 156F 2% RH--it had the same amount of moisture vapor in it going in at 87F 45%RH. The sellers of these can mislead buyers by suggesting the output is "warm and dry". Mine is very hot and relatively dry for that temperature. Barometric pressure can really influence flash off as well with the combination of temperature and relative humidity, I was up at 8,600 ft doing some work and it didn't take me too long to figure out it was not like being somewhere near sea-level.
 
It's always humid here, right now it's 82% RH. Gets worse late May through mid August. Best time to paint is Aug-Oct otherwise just have to deal with it. AC will remove some but reheating the AC air is the best way to remove it. After I left my manufacturing job of 35 years I worked at a hospital for 1.5 before retirement. They had 6 Daikin walkin rooftop units that I got stuck servicing. 3 of the units were multi cycles units with steam boilers to keep surgery / Lab and Pharmacy at 40-48%. They had a tech come in to cali. the monitors once a year. I just have a cheap wall mount monitor that I recalibrate off the NWS station 2 miles away.

John
 
In Georgia, we have perfect paint conditions for about 10 mins a year.
Shot a deck lid 3 weeks ago while raining and 40 degrees out 75 in the garage.

Personally, I pay no attention except at pollen time and I never paint at night for bugs.

The humidity will act as a retarder to a point as it changes the evaporation rate but im religious on my flash times and never very but once about ten years ago on the 4th coat and learned my lesson.
 
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The humidity will act as a retarder

I thought the tin in the clear accelerates the cure when it's humid. That must be after the initial flash? I don't know the terminology. I still wear a shirt with my name on it, in case I forget.
 
It does but sort of a washout as humidity affects the tail solvents evaporation point the most.
Where trouble can arise, adding too much polar or bad gun adjustment or a run.
Then you can get co2 gassing or iso clumping.
 
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When humidity is high, like while raining, I allow at least 30 min flash time
between clear coats, more is better and for my normal collision repair work
3 coats of clear is all I use. On bumpers which is most of my work,
2 coats is enough because I don't cut and buff them.
 
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