Protecting Precision Tools From Humidity-Induced Corrosion

For this I would make a small cabinet with an incandescent light bulb in it for heat. With a normal socket, you can try various wattages to see what is enough.

as the last comment ie locker with bulb and also a small domestic dehumidifier unit will do it.

Along this line, look at the hot boxes or dry boxes that welders use to store welding electrodes in to keep them free of moisture (moist rods lead to hydrogen inclusion in welds which causes embrittlement).

"many precision measuring tools" may preclude a cabinet, but that'd be the way to go if you were talking about a few cubic feet. You might consider sealing the room, if needed, and using a small de-humidifier. You can adjust them to run only when needed. Considering the cost of your instruments, it would probably be a small investment.

We run one in our Minn. basement all winter long.

Keep in mind that the ability of the air to hold humidity is determined solely by temperature. For example, if the air is at 20°C, it can support about 15gm of H₂O per kilogram of air. However, when the temperature drops to 15°C, it's ability to support moisture drops to 10gm. The reason you have humidity precipitating out on your tools is because the surface temperature of your tools is below the dew point of the air. Dew point simply being that temperature at which the total humidity becomes greater than the air can support.

The suggestions here are all valid. Adding some kind of heating device to your tool cabinet will help to keep the air temperature above it's dew point, and desiccants in the toolbox will help remove the humidity in the vicinity of the tools themselves. And obviously, a dehumidifier will also help. Simply heating the shop itself would probably do the trick as well, though one supposes that it might be costly depending on how well insulated the room is. But then, it is only 80ft².

One thing you might consider is acquiring a wooden tool chest for your precision tools. For generations, an oak tool chest was considered the ideal place for such. In particular, a wooden chest has the advantage of being able to absorb considerable moisture all by itself.

I do have a wood tool chest, but it is made from mahogany. Will that protect as well as oak?

It should, but I would still want to put packages of desiccant into each drawer, and replace them regularly. And I would seriously consider heating your shop. How cold does it get in there?

corrosion? Metal? WD40 or unsalted lambsfat or saturated wax or petroleum jelly.

I remember machine shop at Pearl Harbor on the pier, corrosive high humidity environment.

Recommend light machine oil and some infrequently used items wrap in oil cloth and use the oil every day. Eventually the tools may acquire what is termed a browned finish...lots specialized applications available but this is tried and true

Hi,

wooden (any type) cabinet is good for equalizing day-and night changes.

But longterm too high humidity will pass the walls.

So heating as proposed above is good.

If you add cooling - this would be best.

Think about condensed water on cars in the night: the roofs are radiation cooled and the cool air cannot any longer dissolve the water.

So if you have a rooftop of metal and this has an inclination so that condensed water can be collected and removed (to the outside) then your interior will be mostly dry. But if the outside conditions are mostly foggy this will not help.

Heating and storage of heat: best by solar heating of massive stone walls. These will be warmer than the surroundings and ideal for putting the wooden cabinet.

Cooling and condensing water: where to get the cold? Looking to blue/dark sky (no direct sunlight allowed to this surface!) is most efficient, tapping cold ground-water maybe good too. Using a refrigerator with door open and set to 10 degrees below your ambient temperature will let condense a lot of water at the cooling plate and bring some heat to your place. You need to collect the water and duct it outside - not a big problem. Commercial dehumidifiers working with this principle cost near 500 to 1000$.

RHABE

I suggest you seal your room as best you can. Then invest in an inexpensive dehumidifier. The dehumidifier does two things. It removes moisture from the air, and it slightly warms the space. Both these actions reduce the relative humidity, which is what you want to do to lower the dew point temperature.

This is the most intelligent reply I've heard again so far.

Hey Ronseto-- For such problems I have used zip Lok sandwich and freezer bags for Mikes, calipers etc. I have even seen 1 gal and 5 gal bags if needed. This doesn't add any utilitiy increase to your operation. Just a suggestion!

Simply sealing an instrument in a sample of moist room air doesn't change the dew point temperature of the air (although it does limit the total volume of water available to condense). Put active desiccant in the bag with the tool and you can achieve real condensation protection.

i'm sure you could look it up, but you will want to keep your humidity to 40% or less. The lower you go the more static electricity you might have to deal with. Hopefully you don't care about that. Sensitive instruments require stable temperature as well. If you're trying to measure beyond a thou, the room should be temperature and humidity controlled anyways. NIST standards recommend 68* Depending on how crazy you want to get there are correction factors for thermal expansion. For instance a good round number for steel is 10 millionths of an inch per inch degree (F*). Most are slightly less than this, but it provides a worst case scenario. All I'm saying is if you really have precision measuring tools, and if you're worried about the humidity you should probably be worried about the temperature more so...

Perhaps some of these in your toolbox would help.

http://www.corrosionvci.com/vci_vapor_corrosion_inhibitor_foam.htm

In the remainder of my shop(1200sf); when the temperature drops to below 40°F at night, the machines get cold. When the day warms up, warm moist air condenses on the cold iron surfaces, like on the table saw, lathe, etc. I have to squeegee the water from the surfaces of the machines. Serious rust forms. I try to keep the iron surfaces coated with wax, but this has to be re-applied regularly. I know that an airtight shop with insulation along with heat would solve the problem, but the cost is beyond my resources.I have a dehumidifier now, but it is too small for the whole shop. I will move it to the dedicated 80sf machine shop as there is where the most valuable of my tools are located.

BTW How long does a packet of dessicant last? How often does it need to be changed? Can it be re-activated, like in a micrewave?

Plain silica aerogel dessicant can be put in a low temp oven (not a microwave) for several hours to reactivate it. Many brands change color from blue to pink as they absorb water so it is a visual indicator when they are in need of regeneration/replacement.

The VCI thing I mentioned is not a dessicant, it actually emits a vapor that inhibits corrosion. but it really only works in an enclosed space.

If your primary concern is some large iron surfaces, you can heat those surfaces by any number of means, to maintain their temperature above the lowest dew point. This is how your windshield defroster works.

Another possible fix is to get some Break Free Collectors oil from any major gun supply house - costs about $8.00 FOR A 4 OZ bottle. Apply it lightly to surfaces you want to protect. One application will prevent corrosion for about five years.

Of course there's always cosmoline.... it can be purchased any number of places still, it is still on the DoD QPL list. During WWII, coastal artillery batteries had crews whose sole job was slathering cosmoline onto the guns daily to keep the salt air from corroding the guns into worthlessness. They got it by the 55 gallon drum. Those crewmembers were called "cosmoliners". If it worked for coastal gun batteries, it ought to work for you.

Yeah, except I have to use those tools every day. It's not long time storage.