Replies

1. 
   Elcoholic | Oct 21, 2003 05:40pm | #1

   I'm not a scientist but I'd definitely say yes.  Moving air fights condensation.

   John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne

2. 
   bill_1010 | Oct 21, 2003 07:26pm | #2

   Condensation is a result of the air temp being different then the object.   Warm air holds more moisture then cold air.  The air near the object is changing and it usually means the water is forced out of the air.

   COndensation will always happen, however air circulation would allow that condensed water to evaporate back into the air.   Youll still have oxidation.  The best remedy would be to watch the humidity in your workshop to reduce the vapor in the air so when the air does meet an object of different temp.  there is less water to condense.

1. 
   FGP | Oct 22, 2003 12:52pm | #3

   Thanks for explanation WmP.

   I think that you are telling me that;

   1. keep the shop warm - this is expensive.

   2. keep humidity as low as possible - also expensive.

   3. keep air circulating with a low wattage fan - not expensive (but not as effective as 1. & 2.).

   My feelings are that 3. IS USEFUL insofar as rusting is time dependent; if condensation is removed fairly quickly then no harm done.

   You have answered my question, thanks.

   Fred at Kington in UK.

1. 
   UncleDunc | Oct 22, 2003 10:37pm | #4

   Another possibility is to put a heater in your toolbox. It doesn't take a great deal of electricity to keep all your tools warmer than ambient, which guarantees no condensation. The box doesn't have to be airtight, just restrict circulation enough that the heater can keep up with the convection. I don't recall seeing ads for these in FWW, but I have seen them advertised for pianos and gun safes. Goldenrod (or Golden Rod) is one brand name. No endorsement implied, it's just the one I remember.

3. 
   Steinmetz | Oct 22, 2003 11:14pm | #5

   Fred, A small lamp bulb placed in your tool cabinet, plus packets of dessicant (sodium silicate)

   will keep oxidation in check Stein.

4. 
   john | Oct 22, 2003 11:22pm | #6

   The air in the workshop will always be a little bit warmer than that outside, and that in itself will help to keep the humidity a bit lower. Other important factors are to keep the moisture out. Concrete floor? Does it have a damp proof membrane underneath? If not then I suggest applying one over and then laying hardboard (masonite) over it. Then line the walls and the ceiling of the workshop with  damp proof material. Stop all the drafts getting in. Do all that and a cheap £130 de humidifier will do a good job of keeping the humidity below the rusing point. I'm in the UK and haven't had a tool rust on me in years

   John

1. 
   Malcolm2 | Oct 23, 2003 06:54am | #7

   My first reaction when I read the top question was that circulating the air may make condensation worse! Moving air dries wood (and clothes) faster than still air, and if the moving air is contained in a room, then maybe the average humidity in the total air mass in that room would increase if it was moving - and so increase the risk of condensation and rust. What do you physicists think?

1. 
   bill_1010 | Oct 24, 2003 02:40am | #8

   moving air really doesnt dry the wood.  What is happening is new air moving through the woodstack brings in air that isnt saturated with water vapor while moving out air that is water saturated.

   Consider it a conveyor belt, new air is empy while the air going out is full. The wood deposits vapor onto this "conveyor belt"

   All air has a dew point, and condensation is a result of air reaching its dew point. 

1. 
   Malcolm2 | Oct 24, 2003 04:22am | #9

   Agree. Same with wet clothes on a line. But in a closed room does this effect mean that the humidity of the whole room increases? Your wood stack is in an open space. Tools and machinery in a closed workshop are not. Just wondering, quite happy to be wrong!

1. 
   bill_1010 | Oct 24, 2003 07:08am | #10

   in a sealed room, once the air reaches 100% humidity for the room temp, "drying" will not occur.  However if you continue to heat the room, the air can hold more vapor.    Thereby reducing the water in the object, transfering it to the air. 

   However once you reach 212/f 100/c water converts to vapor.  Im sure a person well learned in physics can go into more detail. 

2. 
   FGP | Oct 24, 2003 02:12pm | #12

   Kiwimac2.

   You have stated some serious truths but the original question remains. To my mind  if the air is in motion then any condensation should theoretically be removed by further evaporation - but this would further reduce the temperature of the cold surface on which condensation had taken place thus increasing the chance of condensation. I think this is what you are saying.

   I cannot see where this thinking leads - the question remains unanswered! I think I'm going to forget it and just concentrate on keeping warm.

   Fred.

   Thanks to others for their responses.

   FGP

2. 
   FGP | Oct 24, 2003 02:00pm | #11

   John,

   Thanks for suggestions - I've taken note and am on my way to attempt to improve matters. We are only fifty or sixty miles apart but you wouldn't believe the instances I experienced last winter. I found my heavy machines simply DRIPPING in condensation (usually after becoming warmer outside). I'm determined to remedy this and in fact most of the roof is already insulated. I'm putting in lots of silica gel sachets and have just ordered some XMP spray from Axminster. You will have noticed some other interesting suggestions from other Forum members. I like the idea of fitting a light bulb in the tool cupboard. I once knew a guy who kept a a huge 200watt lamp in the knee-hole of his desk - reckoned this was cheaper than room heating!

   However, you can see from the replies - my original question is not easily answered. Does a fan help or does it not? Thanks, nice to hear from you.

   Fred at Kington, Herefordshire, UK.

5. 
   randyth | Oct 24, 2003 10:47pm | #13

   Air movement only causes a faster mixture of different air masses.  If two air masses have identical properties, air movement will have no effect on condensation.  That is, if the air mass in an air tight room is at a constant 72F and 55RH, a fan within the room would have no effect on condensation. 

   If the air conditions between two rooms were different, a fan would mix the different masses toward equilibrium--faster.  If room A was 65F and 20RH, and room B was 75F and 80RH, a fan circulating air between the two rooms would cause a much faster change in the temperature and Relative Humidity in both rooms.  Assuming equal size air masses and structures (heat sinks) in each room, the air temperature shoul equilibrate near 70F.  The relative humidity in room A will increase, and the RH in room B decrease.  Until equilibrium was reached, you would have condensation in room A and evaporation of any condensate in room B.  Once equilibrium between the two rooms was reached, the fan would have no effect.

   This is true at both the macro and micro level.  Consider sweat on an arm.  The micro atmosphere 1/100 inch above the arm surface has a higher RH and temperature (generally) than the surrounding air mass.  No air movement results in a slower evaporation of sweat from the arm and a slower feeling of coolness.  Sit in front of a fan, and voila, coolness.  You are mixing the air directly around your skin with drier air more rapidly allowing a faster rate of evaporation.  Note, on hot, humid days, that fan doesn't work as well.  The micro environment around your skin, and the temperature and RH of the surrounding air are already near equilibrium. 

   If your tools are in a room with abnormal temperature fluctuations, you will get condensation on your tools.  Those large, bulky, metal tools take longer to equilibrate temperature-wise.  When the room temperature rises, tool temperature does too, only at a slower rate.  (and vice versa)  If the dew point temperature of the air is higher than the temperature of your tools, condensation is going to occur.  The dew point is the temperature where the air becomes fully saturated with moisture.  Condensation on your tools is like arm sweating in reverse.  In this case, air movement will mix the micro air environment around your tools and equilibrate it with the surrounding air.  This will help keep the "micro dew point" around your tools higher and help stop condensation.

   Seems to me, the best solution is to avoid temperature and RH fluctuations.  If this is not possible, use a fan for mixing.

1. 
   FGP | Oct 25, 2003 02:51pm | #14

   Dear RT,

   Thanks for this excellent explanation - a treatise almost! I am now certain that you are correct in every detail. A point that I had not mentioned earlier was that my condensation problem only becomes apparent when the outside temperature RISES and the heavy metal machines are slow to reach equilibrium. Your explanation covers this process wonderfully. The use of a non heating fan as you imply merely accelerates the equilibrium state (the desirable state). Thanks to you and others who have kindly responded.

   Fred in Kington, UK.