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Rust is the Enemy

Susquatch said:
Ah, I see! There is the answer I was looking for. You let your shop go below freezing. This changes the dynamics considerably because it presents the opportunity for a change of state.

If the air in your shop is that cold, it hardly holds any water at all. Almost anything (yes even your breath) will increase the relative humidity in a heart beat and any moisture in there will collect wherever it can. It can't dry up because it is frozen. Most likely the relative humidity in your shop stays at the dew point for the first little while because of this excess frozen water that condensed out while the garage was cooling down the night before.

I have water pipes in my shop. So I never let it go below freezing lest I burst a pipe.

II will say that it's amazing to me that you don't have a crap load of rust in your shop just from the overnight freezing. It's a testament to the anti-corrosion chemicals you use.
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My old shop did as it had no running water. The Garage (attached to the house) generally doesn't drop below freezing but it can on occasion (I have heat trace on the water lines) still runs into the same issues. The condensation only occurs during the heat cycle. Remember the metal stays warm during while the shop cools. During weather warming and cooling cycles (even if extreme they are usually slow.
 
Degen said:
My old shop did as it had no running water. The Garage (attached to the house) generally doesn't drop below freezing but it can on occasion (I have heat trace on the water lines) still runs into the same issues. The condensation only occurs during the heat cycle. Remember the metal stays warm during while the shop cools. During weather warming and cooling cycles (even if extreme they are usually slow.
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You park a car in there or bring in a snow blower?
 
Canadians are spoilt… Our living area is mostly 21C year round (my wife no longer wants to save energy in the summer, so the AC is set for 22C, maybe I’ll sneak it up to 23C but that won’t last long…). In the summer we dehumify, in the winter humidify…
When I was a boy, if it was 10C outside it was 10C inside… The coldest I’ve ever been was in Australia… a cold winter chilled you to the bones. It was too expensive to space heat… (or so I was told…)
Anyway, enough rambling on about “when I was a boy”… back to the original topic.

I purchased a five gallon container of orange desiccant, and once it had absorbed water it could be dried out in the oven and reused. It was used to keep humidity out of a crated engine. I suspect it would work for covered machinery also?

I‘ve used T9 Boeshield and it works very well. My lathe spent a winter sharing our garage with our vehicle and it didn’t get any rust (Unheated, attached, insulated garage). I did liberally coat any bare metal surfaces with oil quite regularily.

For my woodworking tools I’ve had very good success with ProtecTool Wax from lee valley. The only issue I’ve had is putting too much on and then it gets gummy.
 
Degen said:
Neither, all building pull in moisture under the right conditions, most of it comes from humans.
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Of course they do. But the thing I'm struggling with is trying to understand how your garage manages to increase humidity to 100% in an endothermal environment. The only way I know of to do that is to melt snow or ice or to add a mister of some kind. Humans produce a lot of water both breathing and sweating, but not anywhere near at a rate fast enough to increase humidity sufficient to overcome the rate of heat being added with a furnace.

I accept your observation as factual. I believe that you actually do see water droplets forming on cold steel when you turn the furnace on. Since I know that cannot happen in a closed system, I am trying to figure out how such a large volume of extra moisture is getting in there.

You have ruled out melting snow and ice, you have ruled out standing water, and you have ruled out moisture from exhaust gases from your heater. But A LOT of additional moisture has to be getting in there somehow.

The science of humidity and water condensation has been exhaustively studied and the physics mechanisms are very well known.

Briefly stated, cold objects sweat because they chill the air adjacent to them below the dew point for that air. If we know that there was no sweating before heat was added to the system, then we also know that the relative humidity of the air at the surface of the object was below 100%. Therefore any additional heat added to the air will eliminate any potential for sweating because adding heat reduces relative humidity fast. I say fast because the amount of water that air can hold increases exponentially with temperature. The psychometric curve is an exponential curve, it is not linear

Thinking about what you said though, there is one more possibility. If you are actually standing there breathing on your metal surface while you watch it, it will probably sweat. That because you are breathing out very warm very wet air. The air you breathe out is not a high volume at all compared to the air volume in your garage. But if your breath is accidentally or intentionally directed toward a nearby cold surface, it will necessarily cause condensation on the metal surface because the air in your breath will be cooled by the metal below its dew point.

Is that perhaps what you meant all along?
 
StevSmar said:
Canadians are spoilt… Our living area is mostly 21C year round (my wife no longer wants to save energy in the summer, so the AC is set for 22C, maybe I’ll sneak it up to 23C but that won’t last long…). In the summer we dehumify, in the winter humidify…
When I was a boy, if it was 10C outside it was 10C inside… The coldest I’ve ever been was in Australia… a cold winter chilled you to the bones. It was too expensive to space heat… (or so I was told…)
Anyway, enough rambling on about “when I was a boy”… back to the original topic.

I purchased a five gallon container of orange desiccant, and once it had absorbed water it could be dried out in the oven and reused. It was used to keep humidity out of a crated engine. I suspect it would work for covered machinery also?

I‘ve used T9 Boeshield and it works very well. My lathe spent a winter sharing our garage with our vehicle and it didn’t get any rust (Unheated, attached, insulated garage). I did liberally coat any bare metal surfaces with oil quite regularily.

For my woodworking tools I’ve had very good success with ProtecTool Wax from lee valley. The only issue I’ve had is putting too much on and then it gets gummy.
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Obviously, you are not a Canadian Farmer..... I dunno about others here, but I don't live in 21C all year long at all. I live in freezing cold winters and hot humid summers. Even at night when I am indoors, the house is kept cold in the winter and hot in the summer. Not as cold as outside of course, but still much colder than 21C.

In fact, my tools have it better than I do! So I guess I have spoiled Canadian tools! LOL!

Ive used volume dessicant too. But frankly it is too difficult to use in tool boxes, tool cabinets, and boxes. And it doesn't work well for a large shop either. It works reasonably well in small sealed boxes. But it seems that VCI is largely displacing dessicants as the preferred way of protecting things from corrosion today.

And yes, lots of coatings work well. They are just difficult to use and maintain. It would be good if there was a better way.
 
The issue with humidity and condensation on tools is simple, as you heat your work area (particularly if you let it get near freezing or below) for a longer period the metal cold soaks. What happens as you heat the shop the relative humidity changes (temperature dependent) except at the surface of the machine as it near freezing. What happens next can best be described as your heavy metal machine becomes the shop dehumidifier by pulling any and all moisture out of the air and condensing it (unfortunately) on its surface. Over all this is not the extra moisture from unknown sources, but by letting the machines cold soak and then heating the shop when we need it we create a clone of the dehumidifier.

To be fair different heating methods can cause issues, but overall if cold soak can be avoided, condensation can mostly be avoided, again unfortunately some shops can not do this so other preventative measures need to be taken
 
Degen said:
The issue with humidity and condensation on tools is simple, as you heat your work area (particularly if you let it get near freezing or below) for a longer period the metal cold soaks. What happens as you heat the shop the relative humidity changes (temperature dependent) except at the surface of the machine as it near freezing. What happens next can best be described as your heavy metal machine becomes the shop dehumidifier by pulling any and all moisture out of the air and condensing it (unfortunately) on its surface. Over all this is not the extra moisture from unknown sources, but by letting the machines cold soak and then heating the shop when we need it we create a clone of the dehumidifier.

To be fair different heating methods can cause issues, but overall if cold soak can be avoided, condensation can mostly be avoided, again unfortunately some shops can not do this so other preventative measures need to be taken
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That is mostly a wives tale. The science says it doesn't happen that way. To do that, the air next to the machine would have to increase its moisture by attracting moisture from elsewhere.

Looking at it a different way, the air right next to the machine doesn't know the heater has come on. It wasn't below the dew point beforehand, and there is nothing to make it colder because it's already as cold as the machine. So it can only reduce its humidity as it warms. Even if it never warms, that little piece of air can never get to a higher water content than it had when it started. Unless more water is added.....

Similarly, other units of air elsewhere in the room are warming, but their water content is not changing either (unless water is added) so their humidity level is diving. Even if air currents take them back to the machine where they cool, their water content does not change. Therefore they cool but never colder than the machine which was a temperature above their dew point.

Most of the wives tales on this matter are the result of higher daytime humidity from lots of sources including humans, overnight cooling below the dew point, and water that condensed when the dew point was reached during the night but not noticed until after the heat comes up a bit.

Another source for the wives tales is the result of excess water someplace (ice, frost, puddles, leaks, people breathing on things, drips, sweaty concrete, wet towels, etc etc) that increase the relative humidity faster than the heater can compensate.

The third source of the wives tales happens with a well sealed cold room that is filled with cold air slightly above the dew point with cold machines and equipment in it. If the doors are opened and a rush of warmer more humid air enters the room (from outside or from inside the house), that warmer air mixes rather quickly with the rest of the room air significantly raising the average overall humidity. Because it usually does have way more moisture in it, that excess water can condense when it encounters the cold machine. Not only that but because warm air holds so much more water than cold air, it doesn't take much cooling from those giant heat sinks to condense that water back out of the air. Here is a rather interesting corrolary of that science. If you mix equal parts of air with one part at 30 degrees F and 50% humidity and the other part at 50 degrees F and also at 50 % humidity, the result is air that will be 40 degrees F, but much higher humidity. Prolly 70 % or so. You can do the exact calc using a psychometric chart if you want by obtaining the pounds of water for both samples and then looking up the humidity using that new total mass. If both parts were at 100%, guess what happens? Yup, lots and lots of dew! This is the outcome of that non-linear relationship I described earlier.

In summary, there is no science to support what you think is happening. Nonetheless, what you saw did happen. You just need to figure out why/how it happened. Hence my desire to help you find it. You cannot fix a problem if you don't know why you have it.

If that doesn't make sense, I'd be happy to try and explain the nuances further and/or explore other explanations with you that you might suggest. Might be better in a phone call to avoid boring other members to death though. Or better yet over a few beers to improve the efficiency of the discussion... LOL!

Edit - here is an experiment you can try. Next time it gets cold in your shop, take a big block of cold steel from your shop, put it in a big zip-lock bag, and then bring it inside the house. No dew will form on it. Do the same thing with another one but leave the bag open. It may or may not end up with condensation on it depending entirely on the humidity level in the house.
 
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Love to see it @Degen. You already have my contact info. Please send it along. I'll happily retract anything I said that is wrong and then embrace that knowledge going forward. Many times, learning new things means admitting when you are wrong. But just a heads up, I've proven big window companies wrong on several occasions already in my life. Wives tales exist in all fields, and in all industries, at all levels. I'm sure I'm guilty of believing a few too. For example, my father in law could divine water. I still can't understand how he did it, but I watched him do it multiple times. I'd pay money for a scientific paper that explains that one! LOL!
 
Degen said:
Sorry to burst you bubble on this one I have documentation to say otherwise after being in the window industry.
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We let our cottage freeze over winter and sometimes in the spring when we go there the windows are all frosted up, on the inside!!!

It happens after a warm spell and then there’s a cold snap.

The cottage is pretty well sealed, though no doubt there is some air infiltration and moister air introduced when it’s warm.

But it surprises me every time I see it, because I think the the relative humidity of the air must have dropped way further as the air heats up, so where did the moisture come from?

It must be something like when the windows get even colder than the inside of the cottage, the water molecules that are bouncing around in the air stick to the windows and freeze and eventually accumulate, regardless of the overall relative humidity of the air?
 
StevSmar said:
We let our cottage freeze over winter and sometimes in the spring when we go there the windows are all frosted up, on the inside!!!

It happens after a warm spell and then there’s a cold snap.

The cottage is pretty well sealed, though no doubt there is some air infiltration and moister air introduced when it’s warm.

But it surprises me every time I see it, because I think the the relative humidity of the air must have dropped way further as the air heats up, so where did the moisture come from?

It must be something like when the windows get even colder than the inside of the cottage, the water molecules that are bouncing around in the air stick to the windows and freeze and eventually accumulate, regardless of the overall relative humidity of the air?
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Your first instinct is correct. Lots of air does get in and out especially when the temperature changes. In fact, the temp cycles actually force the place to breath in and breathe out as the air expands and contracts.
 
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Why would a floor drain stop working? It’s worked fine for 3 years then in the last couple weeks won’t drain. It’s just a hole cut in the slab, with gravel underneath
 
How much rain have you had recently @Chicken lights ? We had 2.5 inches on Monday. The outside water was up 2/3 of our basement windows. It was like looking outside into an aquarium. Fortunately I noticed how much rain was coming down and saw the windowz early enough to be able to use a shop vac to keep up with what came through the window seals.

If your ground is as saturated as ours is right now, the water has no place to go. I'd bet the gravel under your shop floor is filled with water.
 
I don't have a drain in my shop but wish I did.

If your gravel is saturated, you may have to break an opening for a small pit and sump pump that just shoots water outside a few dozen feet or runs into a storm drain. It would probably only run a few times a year. But it would save you from this.
 
@Chicken lights

You could drill a hole 10 feet away and see how wet the gravel is there. Just drill a hole someplace you can plug later and stick a rod down into the gravel. When you pull it out you will know the story. You could also put a small pump into that hole to act like a sump pump with a water hose going outside till you get the water level down. If you lived close by I have a pump you could use. Crappy tire or home hardware might have a little giant.
 
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