Dan Gelbart posts unusual shop tricks

[Susquatch]

I try to aim for a humidity of around 50%

Corrosion can occur at humidity levels below 60% but it is rare and requires other conditions.

For example, machinery that is colder than the room air and that have high thermal inertia can cause a boundary layer of high humidity air at the surface of the machinery that can result in corrosion. Another potential problem is tool drawers and cabinets that can trap warm high humidity air. When the room cools around them, that moist air in the cabinets can cause moisture to condense on tool surfaces. I try to keep drawers open enough to prevent this and for cabinets and containers where I can't, I put a ZeRust Block inside.

Normally, air that has stabilized at humidity levels of 75% or lower will not result in any significant corrosion.

However, I set my Dehumidifier for 50% and run a big fan to provide a safety margin for areas of my big shop with poor air circulation.

In my case I think my basement is a little damp and it doesn't matter how hard I crank the dehumidifier the humidity barely drops. If it drops its only because it makes the temperature go up a little.

This is a very real problem. As @mbond says, not much you can do to fight basic thermodynamics. If your basement is adding as much water to the air as your Dehumidifier is removing, about all you can do is heat the air and/or maybe pump dry air into the basement from the rest of your house.

Have you measured how much water is being removed? At low temperatures, it won't be a lot because cold air doesn't hold much water. In my basement, at the beginning of the humidity season (summer), I get about a 5 gallon pail of water a day for a week or so. Then, as the basement starts to dry out, that will slow down a great deal. Basically, it takes a while to dry out wet surfaces, wet rags, and wet concrete.

I do have a couple of humidity meters but don't find them very accurate. (two meters often disagree and take turns on which one is higher).

This is normal. As long as they are within 15% of each other when they are side by side and have stabilized for a few hours, I wouldn't worry about it. Even a lab grade meter will vary a fair bit. If you ever find a really good affordable one, please let me know.

 

[BaitMaster]

I do absolutely nothing to keep things from rusting, other then keep things inside. And gently oiled.

Humidity is not a problem around here. At all. Foreign concept that you guys are like humidity scientists. lol.

 

[mbond]

Humidity isn't something that can be measured directly in a reliable way.

Relative humidity is the ratio of the current level of dissolved water versus the maximum level of dissolved water. In still air, the maximum level is usually calculated from the temperature and pressure (and an assumption about what gasses are in regular air). The electrical resistivity can give an estimate of how much moisture is actually present. Take all of those together, and factor in the error in each measurement along with the assumptions, and it is no surprise that the results don't inspire a lot of confidence - hence what Susquatch says about 15% difference being essentially the same reading

As to your actual problem, how good is the water proofing in your basement?

 

[DPittman]

I do absolutely nothing to keep things from rusting, other then keep things inside. And gently oiled.

Humidity is not a problem around here. At all. Foreign concept that you guys are like humidity scientists. lol.

Ain't it great?

 

[BaitMaster]

Ain't it great?

It is nice for keeping machine tools in good shape.

But I do love the ocean, and I am a long way from it.

I swam in the pacific last year first time in about 7 years and boy, it was cold. But I miss it. I was out on the coast for a couple jobs, and grew a love for the water.

 

[Bandit]

I don’t know how good the water proofing is in my basement, never tried to keep water in it. LOL.

 

[Canadium]

.....

As to your actual problem, how good is the water proofing in your basement?

I have a very old house. The outer basement walls have relatively new waterproofing but the floor remains damp. The concrete in the floor is so old it seems to have become porous and I think the water table is close to the basement floor. The house is so old it doesn't really warrant expensive remedial repairs. Makes more sense to just tear it down and rebuild. I'm getting a little old for a grand project like that tho.

 

[Susquatch]

The outer basement walls have relatively new waterproofing but the floor remains damp.

Sounds like rust and you are BFF's.

I'd be trying a big Dehumidifier if I were you. Just run the drain into your sump pump hole.

General PDP Template

www.canadiantire.ca

I'd set it for 40% and just let it run for a few weeks. Unless your water table is really high, you might be pleasantly surprised by how dry your floor will get with time. Canadian tire will accept returns in that time.

If you have central air, you might need to increase your basement air flow vs the upstairs. Home air conditioners are surprisingly good dehumidifiers.

But sometimes they have too much air flowing through the condensor. At my old house, I added a cardboard restriction to the filter to slow the air down. It was like a miracle. Within days we had a nice dry house. Basically, the air has to flow slowly enough through the condenser to be able to reach the dew point in the condensor - otherwise, the air just gets cold and doesn't get cold enough to dehumidify. It's kind of counter intuitive.

 

[Canadium]

Sounds like rust and you are BFF's.

I'd be trying a big Dehumidifier if I were you. Just run the drain into your sump pump hole.

General PDP Template

www.canadiantire.ca

I'd set it for 40% and just let it run for a few weeks. Unless your water table is really high, you might be pleasantly surprised by how dry your floor will get with time. Canadian tire will accept returns in that time.

If you have central air, you might need to increase your basement air flow. Home air conditioners are surprisingly good dehumidifiers. But sometimes they have too much air flowing through the condensor. At my old house, I added a cardboard restriction to the filter to slow the air down. It was like a miracle. Within days we had a nice dry house. Basically, the air has to flow slowly enough to be able to reach the dew point in the condensor - otherwise, the air just gets cold and doesn't dehumidify.

Been there done that! The dehumidifier will not take the humidity down to 40% ever! Maybe 55% if I'm lucky! All the dehumidifier accomplishes is a big electricity bill. And here's the kicker. My steel tools actually rust far less in my humid basement than in my garage where humidity is usually far lower! Why??? Because the temp in my basement is very steady whereas temps in my unheated garage follow the wild swings of the outdoor temps. Consequently steel in my garage is often colder than the dew point and gets condensation water on it but that never happens in my basement!

 

[Susquatch]

The dehumidifier will not take the humidity down to 40% ever! Maybe 55% if I'm lucky! All the dehumidifier accomplishes is a big electricity bill.

I was only suggesting a set point of 40% to keep it running full time to draw down the space humidity and dry out the concrete over the course of a week or two.

55 or even 65% is just fine for an actual stead state humidity level. The lower the better of course, but sometimes you have to take what you can get.