# Shop Humidity Percentage Goal?



## Stonebriar (Jul 20, 2014)

I have my shop here in the south where humidity is an issue.  I have rescently installed air and heat, but don't run them all the time.  I bought a de-humidifier and wonder what percentage would be ideal to keep the rust off my tooling. The range on it is 35% to 60% any suggestion for a good number?

Thanks,
Rick


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## sinebar (Jul 20, 2014)

I live in the Hudson Valley and it gets quite humid here too. In my basement shop, I keep my dehumidifier set to 55%. It keeps the shop dry enough and it doesn't have to run 24 hours a day at that setting. The dehumidifier helps a lot, but I think it is more important to keep the bare metal surfaces of my machines protected. My shop is part metal shop and part wood shop. I use Boeshield T-9 or paste wax on my wood machines and I keep my metal machines clean and well oiled. So far, I don't have any rust problems.


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## Tozguy (Sep 28, 2014)

My shop is kept between 50 and 55 % relative humidity. Dehumidifier runs constantly for three summer months. It is turned off for winter months when humidity  goes down naturally to 35 %.


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## Tony Wells (Sep 28, 2014)

Emory is not far from me, so I imagine the humidity is not too different. I have a hygrometer on the wall and glance at it once in a while. On hot summer days, before I run the air, it is pretty close to what the weatherman says. I can be quite high on days in the summer when thunderstorms are forecast, but I have found that anything below 40% is uncomfortable to me to breathe, and my eyes tend to dry out. 60% is comfortable, but I have always thought that since Metrology labs are kept at 68°F @ 50%, that is my target most of the time. It's not always easy to get to the 68° part, but the humidity control is no problem. I have no issues with rust on bare metals. The machinery stays oily enough though, so it doesn't have a problem.


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## GA Gyro (Sep 28, 2014)

Not sure if this helps... however in the heating and AC business we advise 45-50% RH at 73-76 DF as ideal conditions in one's home in the summer.  In the winter 40-50% RH and 65-68 DF is easily achievable without busting the energy budget.  A humidifier is not a bad idea in the winter... albeit sparingly.  Keep your filter clean!  
When the RH is in a comfortable range, one can set the thermostat to higher temps in the summer and cooler temps in the winter and be comfortable, thus lowering one's energy costs.    

Since my shop will be in the basement, I am thinking to follow those guidelines.

Regardless... probably keeping metal coated with oil... is cheap insurance.


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## Stonebriar (Sep 29, 2014)

Well here is what I wound up doing.  I air conditioned my shop, thanks to my brother in law. He gave me a 2 year old unit someone pulled out for a larger one. And bought a dehumidifier.  I set the humidity level a 45% on the dehumidifier.  It keeps the humidity level at a good place when the air is not on. It has been very pleasant in there and has eliminated any surface rusting issues I was having.  This seems to be working great.


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## bedwards (Sep 29, 2014)

I run the air only if I am in the shop but run a dehumidifier 3 hours a day on a timer in the summer. I keeps RH between 50 and 60%. Before then, no real corrosion issues but wood and plastic were trying to grow hair. 


bedwards


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