Is moving air less likely to condense?

[nigelmercier]

I've been thinking of ways to reduce the chance of damp affecting tools in my shed, in particular my new lathe. However this question also applies to boats...

Is moving air less likely to condense on cold surfaces? If so, perhaps a temperature controlled fan would be more useful than a heater.

 

[LittleSister]

Don't think a fan will really help much. Suggest either plenty of ventilation, or wholly sealed up and use dehumidifier. I've known boats and sheds stood for years without getting damp. They all had/have good ventilation.

The other thing is to avoid the lathe (or anything else sensitive/precious) getting colder than the air around it, so insulation from the ground, and a loose cover over the top so its not radiating at the roof (which in turn is radiating at the sky).

A third line of defense is to protect the lathe with ACF50 or similar.

 

[Richard10002]

Ventilation and moving air, so some kind of slow fan, plus vents for it to change the air.

 

[grumpy_o_g]

I've been thinking of ways to reduce the chance of damp affecting tools in my shed, in particular my new lathe. However this question also applies to boats...

Is moving air less likely to condense on cold surfaces? If so, perhaps a temperature controlled fan would be more useful than a heater.

Yes, if warm static air comes into contact with a cold surface it's sools the air above it and allows a considerable amount of condensation to form. If the air is moving it gets far less time in contact with the cold surfaces so less condensation occurs.

Basically either keep the tools warmer than the air, the air coming in cold (and therefore dry) or don't let the tools come into contact with the air.

 

[lynall]

I would be a little worried about the bare metal surfaces on the lathe, especially when the **** weather returns, at work the tools rust like theres no tomorrow.

 

[cliff]

A fan will make SFA difference - clean the Lathe of all cuttings/swarf and give the bed and slides a wipe with an oily rag and/or spray with Contect™ Duckoil or if feeling really rich ACF 50. Finally cover the Lathe with a loose cotton cover.
Do make sure you remove all traces of cutting fluid/coolant even though it is supposed to contain corrosion inhibitors..
DO NOT use propane (or butane) fuelled space heaters in your workshop.
Ventilation

 

[nigelmercier]

Ventilation is not a problem, there's an open 75mm overhang all round the eaves. That's why heating is not an option.

The next bit is completely non-boaty ...

I plan to make an MDF cover for the lathe, lining the top with the polystyrene foam insert it was packed with. Apart from keeping dust out, it will prevent it being seen from the drive if the door is open.

The shed has been a bit neglected recently, but I've given it a coat of preservative and made a new door. Looks pretty smart. I discovered that there had been a build-up of soil along one side of the concrete base, and the adjacent floor rail was rotten. I jacked up the side using a trolley jack and blocks of wood. Cut the rail up to every floorboard join with a chainsaw. Levered off each section, most were rotten from the bottom. Cut off the nails with an angle grinder. Replaced the rail in four 1.2 metre sections with tantalised 45mm square timber. Lowering it down was the hardest part, but got there in the end. Job done, very pleased with myself, so had to share.

Another non-boaty comment. Before making the door I looked online to see if there were any tips. About half of the pictures of ledged and braced doors had the hinges on the wrong side, so the braces were not in compression. I decided to screw and glue the braces and ledges, and glue and ring-shank nail the T&G. My wife said the new door will outlast me.

I am also pleased to report that I still have a full complement of fingers.

 

[Boo2]

I've been thinking of ways to reduce the chance of damp affecting tools in my shed, in particular my new lathe. However this question also applies to boats...

Is moving air less likely to condense on cold surfaces? If so, perhaps a temperature controlled fan would be more useful than a heater.

Best way to prevent condensation on a machine tool like a lathe is to run a low (say 40W) bulb continuously on inside the lathe cabinet itself. This keeps it warmer than the surrounding air and prevents condensation that way. Alternatively run a dehumidifier. I don't think a heaterless fan will help at all.

Boo2

 

[Daydream believer]

I have an aged Drummond lathe & being mainly cast iron I suppose that it is less susceptible to rust. Modern lathes seem to use steel for structure
i do keep it well oiled though
Just had to make new tufnol bearings for my rope stripper which the manufacturer said was past servicing
That on its own has paid for the lathe & some accessories

But good ventilation is the key along with a cloth cover. I suspect that the earlier comment about circulating air not having time to condense on cold surfaces might be wrong as you are actually applying more air to the surface anyway

 

[alant]

I've been thinking of ways to reduce the chance of damp affecting tools in my shed, in particular my new lathe. However this question also applies to boats...

Is moving air less likely to condense on cold surfaces? If so, perhaps a temperature controlled fan would be more useful than a heater.

http://www.newton.dep.anl.gov/askasci/gen99/gen99979.htm

"Believe it or not, at ordinary temperatures all molecules are in a state of incessant motion -- vibrating, jiggling and slipping about. The warmer it is (the more thermal energy the molecules have), the more they move.

Even though water molecules have a tendency to hold on to each other, increased molecular motion encouraged by warmth (heat) makes it increasingly difficult for them maintain their bond to each other. Whenever a water molecule receives enough energy to break loose, it can either keep on moving away from the wet surface or be bumped back into it by collision with nearby molecules in the air.

If the nearby air is moving, water molecules that do manage to jump free of the wet surface are swept away rather than re-deposited. Thus, more wind means faster drying. Of course, this process works even better when the moving airstream is of low humidity."

 

[sarabande]

I use a good car polish on the metal surfaces of e.g. bandsaw, benchdrill, router, etc.. Very draughty workshed

 

[Daydream believer]

http://www.newton.dep.anl.gov/askasci/gen99/gen99979.htm

"Believe it or not, at ordinary temperatures all molecules are in a state of incessant motion -- vibrating, jiggling and slipping about. The warmer it is (the more thermal energy the molecules have), the more they move.

Even though water molecules have a tendency to hold on to each other, increased molecular motion encouraged by warmth (heat) makes it increasingly difficult for them maintain their bond to each other. Whenever a water molecule receives enough energy to break loose, it can either keep on moving away from the wet surface or be bumped back into it by collision with nearby molecules in the air.

If the nearby air is moving, water molecules that do manage to jump free of the wet surface are swept away rather than re-deposited. Thus, more wind means faster drying. Of course, this process works even better when the moving airstream is of low humidity."

Interesting.
One might also point out that cold air contains less moisture ( down to something around 2-3 degrees i think) That is when it starts to regain moisture
So the point being that a warm shed might attract more moisture which will be condensed on to a cold surface ( possibly a lathe!)

So how about fitting an extract fan with a dehumidistat -- would that work?- or would the humidity switch level in the fan be too high for a shed & would it just suck moist air from outside.
If you want to maintain moving air around the lathe it would certainly do that cheaply as some are very energy efficient

 

[JumbleDuck]

Yes, if warm static air comes into contact with a cold surface it's sools the air above it and allows a considerable amount of condensation to form. If the air is moving it gets far less time in contact with the cold surfaces so less condensation occurs.

I disagree. When the air is kept moving there is much less chance for a drier layer to form next to a surface onto which the water has condensed. Think of it the other was: far more water evaporates when the air above a damp surface is kept moving even though, by your argument, the dry air is next to the surface for far less time.

 

[Jassira]

<snip>
. My wife said the new door will outlast me.
</snip>

Good job your not paranoid

 

[LittleSister]

Alternatively run a dehumidifier.

Pointless running a dehumidifier if the area (in this case shed) is ventilated (as he told us it is) - you will be paying good money to try to dehumidify the planet!

 

[grumpy_o_g]

I disagree. When the air is kept moving there is much less chance for a drier layer to form next to a surface onto which the water has condensed. Think of it the other was: far more water evaporates when the air above a damp surface is kept moving even though, by your argument, the dry air is next to the surface for far less time.

I'll have to have a think about that one. Can't fault the logic at first glance...

 

[Vallich]

If you're going to cover your lathe then I suggest you use some sorta breathable fabric to allow any moisture to pass out but none should ingress.

 

[JumbleDuck]

I'll have to have a think about that one. Can't fault the logic at first glance...

Try breathing softly and then more vigorously on a cold window ...

 

[Jassira]

I disagree. When the air is kept moving there is much less chance for a drier layer to form next to a surface onto which the water has condensed. Think of it the other was: far more water evaporates when the air above a damp surface is kept moving even though, by your argument, the dry air is next to the surface for far less time.

not sure if it's relevant but you only seem to get dew on the grass after a still night

 

[cliff]

If you're going to cover your lathe then I suggest you use some sorta breathable fabric to allow any moisture to pass out but none should ingress.

No you may not! I have used cotton machine covers for decades without any problems. You can keep your "breathable" fabrics etc