Condensation in workshops

[corbraeParticipant @corbrae]

Workshop condensation

[corbraeParticipant @corbrae]

Hi There

I have condensation problems in my concrete sectional Garage used as my Workshop, I run a Dehumidifier all day and that helps a lot. I wonder if others have suffered the same problem and how they managed to cure it.

Thanks

Bob Short

[Steve GarnettParticipant @stevegarnett62550]

It’s been quite extensively discussed before – here are a couple of threads to look at:

Surface rusting in worksop

Workshop heating

[Keith LongParticipant @keithlong89920]

Hi Bob

Have a look at the thread “Workshop heating”, there was quite a lot in there about how folks keep the workshops habitable and dry.

Keith

[MikeParticipant @mike89748]

Over the last month I have been trying Superdry dessicant packs in my damp workshop – the big packs suspended from the ceiling near lathe and mill, and small packs in tool containers. A bit early to give you a definitive verdict, but all seems well at the moment. With your dehumidifier, probably just a few packs in with your tools and any stocks of steel you keep would be sufficient. Full details of the products at http://www.airandwatercentre.com.

Hope this is helpful.

[TerrydParticipant @terryd72465]

Hi Corbrae,

 

this is a perennial problem most of us suffer from. I have a detached garage which I use as a workshop (brick cavity wall and insulated ceiling) and used to get lots of condensation. I couldn’t afford to run a large enough dehumidifier. However itthe grage has had to be rebuilt after a fire and I am taking the opportunity to have a couple of large radiators linked to the household heating system which hopefully will help.

 

Of course the long term solution is prevention by modification of your building with insulation, heating, double lining, draught proofing etc etc but this gets expensive and it depends how far you wish to go and how much you can afford to spend..

However that is a rather drastic solution, in the interim there are a few simple things to try including using dessicant products and protective waxes and oils. for a relatively small layout of a few pounds you can provide a good level of protection. I have seen the Superdry products but they seem rather expensive as they are ‘one-shot’ disposable products which cannot be regenerated. As an interim solution I use impermeable plastic covers for my machines, I use heavy duty polythene, some folks advocate cotton, but as that is a good absorber of moisture personally I think not. After all if such plastic (PVC) covers are good enough for Myford, they should be good enough for me. I then keep a 100gm silica gel pack with each machine. This creates a dry micro environment around each machine, the plastic cover preventing more moisture entering.

 

Silica gel dessicant can be regenerated in the microwave in a couple of minutes and lasts for a long time. It is available in 100 gm bags on eBay for for as little as £6.00 for 5 (in. postage). You can even get some small colour change bags to keep in as well which tell you when to regeneration is necessary. Tools can be kept in drawers and cupboards, again with these bags of SG. There are products with which you can protect your equipment by coating barriers, such as waxes and oils. Some examples are shown here at Arc Eurotrade.

 

Best regards

 

Terry

 

 

Edited By Terryd on 30/01/2011 12:38:19

[GoCreateParticipant @gocreate]

My first workshop was a concrete sectional construction garage.

I lined it out, including covering over the up and over door, with a sheet of polythene, then 1″ thick polystyrene and 3/8″ ply. The ply was screwed to a vertical wood battens secured to the wall panel clamp plates. I made a false ceiling with I think 2 x 2 timber frame and 1/8 ply insulated with loft insulation. Because I covered the up and over door, which improved security as this opened onto a street, I made and fitted a side door by removing one set of wall panels.

 

The concrete floor was painted, coverd with lanimate flooring underlay and then a layer of loft floor boards. The boards did tend to waer a bit so later I glued on some vinyl tiles.

 

I heated it with a 2kw convection heater, I had no problems with condensation and did not use dehumidifiers.  I allowed the heater to heat slowly, turning it on a hour before I went in, I think this helps reduce condensation tendancies. after a bout 3 hours it was as warm as toast even on the coldest day.

 

It’s alot of work and expence but I expect cheaper that running a dehumidifier over a period of time.

 

Apart from the floor I have done the same with my current workshop though this is block built and rendered, again I have no problems with condensation

 

My first workshop was in NE england by the sea, my current workshop is in the Grampians Scotland, both locations prone to cold damp weather at times.

 

My experiance is that it’s well worth the effort and expence, it can be tricky and frustrating to do when the workshop is full of your gear.

 

Hope this helps

 

Nigel

Edited By tractionengine42 on 30/01/2011 17:02:11

[corbraeParticipant @corbrae]

Many thanks to all who have read and replied going to re roof when weather gets better

and get rid of the Steel corragated

will advise later

Regards

Bob

[Gordon AParticipant @gordona]

Greetings Corbrae,

It is interesting that you are getting rid of your steel roof when the weather gets better.

I will be replacing my rotting wooden shed/workshop roof with profiled steel sheeting when the weather gets better!

 

I don’t know what you intend to use as a replacement for your roof, but maybe you could retain the existing if it is in good condition and invest in better insulation instead.

I will be using “ThermaWrap” as a vapour barrier and additional insulation (similar products are available). I was surprised to discover that despite being 4mm thick, the manufacturer claims insulation properties equivalent to 65mm of polystyrene!

 

Another insulation product I have used is Celotex ( Kingspan is a similar product). This is a dense rigid foam sheet with aluminium foil either side that has very good insulating properties and available in a range of thicknesses.

Apologies if you have already looked at these products, they are not cheap, but this is the route I am taking to help keeping precious tools and equipment as free as possible of the dreaded metal mould .

 

Does anyone out there remember a magazine article some years ago on making a lathe bed heater to prevent condensation? Basically as I recall, it was a small number of high wattage resistors bolted to a sheet of aluminium which was bolted to the machine bed. This arrangement was powered by a low voltage source with the intention of maintaining the lathe (or miller, or shaper etc.) at slightly above ambient temperature when the workshop was “resting”.

 

Regards,

Gordon A

 

 

 

[Peter G. ShawParticipant @peterg-shaw75338]

Gordon,

 

Not so much make, as buy.

 

I have fitted, and reported via MEW, using a pair of self-regulating 10W heaters available from RS Components. Although these devices are rated at 10W, they actually are taking 18W each, or they were when I checked. Anyway, since then the lathe has never had that bone-chillingly cold feel in cold weather, and has not had any condensation whatsover. I also chuck an old table cloth folded double over it and at one time used to also use a sheet of plastic as well. I don’t use the plastic now.

 

There are alternatives. Dave Fenner, the previous editor of MEW was going to try something else: I think it was the self-heating tape and then report back. I don’t recall seeing it, but can’t see why it shouldn’t work. Someone else used a 10 or 15W incandescent bulb under his bed. In short, the idea is to keep the lathe just slightly above the lowest air temperature thus stopping condensation. It certainly works for me and my garage does have a nasty tendency to leak – usually when it rains heavily if it’s going to do! And anyway, it’s more or less permanently damp – rain gets under the front door, a rear wall often shows signs of damp especially when the wind and rain combine to blow from the SW.

 

Regards,

 

Peter G. Shaw

[TerrydParticipant @terryd72465]

Hi Peter,

Just a few thoughts, sorry it is so long, I won’t mind if you fall asleep from time to time.

 

Another common and cheap heater can be made from a couple of 240V, 15 Watt incandescent bulbs in batten bulb holders connected in series, together with a suitable light switch on a wooden base with a flying lead to a 13A outlet. As the lamps are connected in series they are each receiving 120V so their life can be measured in 10s of years probably (i have incandescents working that I replaced when I moved into this property 18 years ago still going strong – so much for the so called ‘energy saving bulbs’). It is still a good idea to cover your machine with a waterproof cover a lá Myford and keep a desiccant silica gel pack(50 or 100gm) enclosed to reduce humidity.

 

I’m afraid I can’t agree with you tablecloth, as cotton is an extremely good absorber of moisture, hence it’s use in our more intimate garments and summer and sports clothes. (Notice how damp tee shirts remain in hot summer as they absorb body moisture and the ambient humidity of the air does not evaporate that moisture as it’s dew point is higher) It will simply absorb moisture and keep it in contact with your metalwork. A moisture proof cover and dessicant will provide a micro environment with air having a lower humidity in that micro environment, hence higher dew point and less condensation. Plastic above cotton is just about the worst combination – no evaporation.

 

Also it is not enough to keep the temperature of the equipment “just slightly above the lowest air temperature thus stopping condensation.” The temperature must be kept above the Dew point of the atmosphere. The dew point will vary according to temperature and humidity of the air.

 

The dew point is crucial in this process. Hoar frost in winter is formed on trees and bushes when the temperature of the surface of the plants which may be the same as the atmosphere, but it is below the dew point so moisture condenses from the air as it meets the plant and then freezes according to the air temperature. It is the same process when dew form in spring and summer mornings and tropical forests.

 

Insulation and vapour barriers etc are only a part of the solution to condensation. There must also be heat to retain, after all, all that insulation does is retain heat. It does not create heat. My own bungalow has solid insulated floors, cavity wall insulation, 18″ of loft insulation and deep double glazing. We also have sophisticated draught exclusion systems on most doors and windows, not all, to allow air exchange. However if I leave it for a week in freezing temperatures without a heat source I can guarantee that I will have burst pipes and a substantial bill when I return,

 

Keeping condensation away involves a combination of strategies including insulation, providing sufficient heat and creating the correct environment, if this can not be done for the whole space then create micro environments around valuable equipment.

 

I have just had my detached garage workshop rebuilt following a fire and am lucky that the previous owner had the walls built as cavity type. The ceiling is plaster boarded with 180mm of insulation above, it has double glazed windows and a sealed and insulated electric retracting door. This is heaven but I still have to heat the place or all of the insulation etc will be of nothing otherwise. at the moment it has condensation every evening as the temperature falls, I intend to extend the house central heating (underground pipes are installed) into the garage with froststat control. I’ll also create micro environments for each machine and critical area using some of the techniques I have discussed using quite inexpensive methods. I will report on it’s long term efficiency at some future date.

 

Best regards

 

Terry

[Chris CrosskeyParticipant @chriscrosskey26628]

Thanks for this thread, I’m in pretty much a similar boat and was going to ask pretty much the same question…. having measured mine I think I’ll be going for polystyrene 50mm in the walls, 25mm in the floor and loft insulation in the roof with DPM and plasterboard for the walls and dpm and hardboard on frames for the roof… Floor will go DPM-screed-insualtion-floorboards but under the two main machines it’ll go DP-screed-brick-built plinth with absolutley levelled surface. I’ll look at putting some sort of very low level heating in on or near the machines.

 

Looking forward to this, going from my old 11×7 shed to a 17×9 with additional storage…. if nothing elseI’ll have the space to rebuild the mill at last….

 

chrisc

[NJHParticipant @njh]

Terry you right here – I find that the dew point is critical to avoiding condensation.

My workshop is 10ft.x17ft x 7ft and I took a great deal of trouble in insulating it. I have been collecting data over the last year and you may be pleasantly surprised at how little you will need to do to keep the dreaded condensation at bay!

I have been monitoring the temperature and humidity (max and min) and calculating the dew point each day. I have a small oil filled radiator as background heat in the workshop – the attached garage is unheated and I also monitor the temperature there to provide a simulated “unheated workshop” I don’t cover the machines, provide local heat or spray wd etc.

A major advantage of good  insulation is that  changes in temperature are damped – when rapid changes of temperature occur it is easy to encounter the  dew point and experience the dreaded condensation- the damping helps to avoid these swings.

 

Since Jan 2010 the workshop temperature range has been 3.3 min 22.8 max

The unheated section has been -2.7min 21.9 max

At all times the workshop temperature has been above the dew point – no condensation – no rust!

The cost of running the heater for the year was £65. Yes I’d rather spend it on tools or materials but it seems to me a small price to pay to keep a lot of expensive kit in good order. All the data is logged on a big excel sheet with lots of pretty graphs – I am happy to supply further details if anyone is interested.

 

Regards

 

Norman

Edited By NJH on 08/02/2011 18:00:11

Edited By NJH on 08/02/2011 18:03:39

[TerrydParticipant @terryd72465]

Hi Norman,

 

I agree with you. The temperature of the equipment to be protected only needs to be kept just above that of the dew point of the air. I have connected my detached garage to the domestic heating system and am experimenting with the size of radiators at the moment and have quite a small one which seems to be doing the job. i have bought a double sensor (cheap from China of course) thermometer to use as a humidistat in order to keep the same sort of records as yourself.

 

Some folks though see insulation as the solution, when in fact heat is the solution, insulation merely slows down the heat loss for economic reasons. The reason i use plastic machine covers is that the provide an impenetrable barrier for moisture and if you dry the enclosed air you create a dry micro environment meaning that less heat is required. Polythene and silica gel are cheap and effective, and silica gel can be reactivated in a few minutes in a microwave.

 

I also recommend providing a barrier on vulnerable surfaces such as slideways by using chemical barriers such as those provided by Arc Eurotrade. These are my double insurance. My reasoning for the extra protection is that if you raise the temperature of the workshop, the dew point of the air is raised as the air can hold more moisture, so condensation can still occur in certain conditions. It’s a catch 22.

Best regards

 

Terry

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, humidity is the real problem. As far as rusting is cncerned, a cold dry room is better than a warm humid room, but of course a cold room is not comfortable to work in. One other solution to reduce the humidity, but keep the heating costs down when not in use, may be to fit a small extracter fan like those you find in your loo/bathroom, you can get them with a humiditystat fitted, and they will cut in and out automatically, and I have heard that they are very effective.

 

I once saw a programme on TV about an airplane which had to be ditched in the artic during WW2 for some reason. The programme was about some presivation scheme to recover and restore the airplane. Althuogh the airplane had been standing there for 40 odd years or so, there was no rust or coorosion on it because the air was so cold all of the time. This ment that there was no humidity in the atmosphere, no humidity no rust.

 

I’ve found in my unheated garage that things seem to get a little rust on them in damp weather, but not so much when it is cold and frosty. But like Terry I keep my machines covered over with a plastic sheet (piece of damproof membrain bulders use) but as yet don’t have any method of low heating or silica gel, but they do have a smear of oil on them.

 

May be a bit of useless information for you.

 

Regards Nick

[Peter G. ShawParticipant @peterg-shaw75338]

Hi Terry,

 

I don’t know what the old tablecloth is made from. All I know is that it is green, torn, and got a raised pattern on it. Actually, come to think of it, I don’t even know if it was a tablecloth, it’s been there so long. I suspect it’s actually a manmade fibre.

 

Don’t know anything about dew points, hygrostatics or whatever. What I do know is that my system has worked well now for a few years in that rusting does not appear even in the cold weather we’ve experienced recently, so something must be right. Ok, extreme cold means that the air cannot hold as much water so maybe that’s nothing to go by for me.

 

I think that from my point of view, strictly as an amateur, if something works, then that’s good enough and in this sort of situation, where I simply am not interested, deep technical discussions simply glaze the eyes. Don’t misunderstand me – the fact that you do know about it and can advise as such is a bonus not to be sniffed at, and I thank you for your comments. Maybe I’ll resurrect the old piece of plastic as well.

 

Interestingly, I use the same principle on the miller – small heater, miller covered by the plastic bag it originally came in, and on top of that a cloth thingy which came from my parents some years ago. Again I don’t know what the cloth is, suspect something manmade, and probably a seat cover or something similar. (Mother was into making things like that.) Anyway, it does seem to keep it slightly warm, possibly not quite enough as I only use one heater.

 

And considering that the garage has sprung yet another leak recently…..

Perhaps I should take up knitting!

 

Regards,

 

Peter G. Shaw

[The Merry MillerParticipant @themerrymiller]

 

Now Peter,

 

as regards taking up knitting and condensation getting into your balls of wool and onto your metallic knitting needles !!!!

Edited By The Merry Miller on 09/02/2011 15:23:02

[John HardingParticipant @johnharding75458]

Hi, the best route to preventing or removing condensation is good ventilation. As those of you fortunate to still have a bathroom with a window opening onto the outdoors will know that opening the window soon clears the condensation. The standard 4″ fan is pretty ineffective; if using a fan, install a 6″ or 9″ fan and provide a matching size inlet on the opposite end of the workshop.

 

If the workshop is heated only while working in it, then before quitting, it might be worth leaving the door open for a few minutes to flush out the warm humid air.

 

Past experience taught me that insulating a suspended floor makes a really difference. On this occassion I had lined the roof and walls first with polythene to draught proof and then with polystyrene, followed by hardboard. It was only by covering the floor with polystyrene that the shed would hold the required temperature.

 

For several years I stored woodworking tools in all plywood cupboard standing in a garage. Tte cupboard size 4ft high x 3ft x2ft required just one night light bulb of 8 or10watts, which would last all winter. The bulb stood on the floor of the cupboard. I started with 40 watt and then 25 watt bulbs which quickly burnt out.

 

Regards, John Harding

 

[Nicholas FarrParticipant @nicholasfarr14254]

Hi,

Posted by John Harding on 09/02/2011 16:04:32:

 

 

 

For several years I stored woodworking tools in all plywood cupboard standing in a garage. Tte cupboard size 4ft high x 3ft x2ft required just one night light bulb of 8 or10watts, which would last all winter. The bulb stood on the floor of the cupboard. I started with 40 watt and then 25 watt bulbs which quickly burnt out.

 

Regards, John Harding

 

 

At my old company where I used to be, we had steel cubboards for storing MMA welding electrodes which had a 110v 100w bulb. That kept them dry a treat.

 

Regards Nick

[Ian S CParticipant @iansc]

One thing I have used is a solar powered fan to ventilate a shipping container that was being used for storage, it had a battery charged by a solar cell, very handy as the container was out in a paddock away from mains power. Ian S C

[Roderick JenkinsParticipant @roderickjenkins93242]

I don’t think ventillation helps much unless you are actually generating moisture in the room, like in a bathroom.. I used to work in a laboratory that had 20 changes of air per hour. It was in a substantial building with radiator heating. Eveything rusted like crazy because there was a constant stream of moist air being introduced form outside.

 

In the past I used an oil filled radiator, on a timer, behind the lathe which was on a Myford stand. The timer came on from a couple of hours before dawn and this warmed the lathe so that it was not colder than the air. The really bad days were after a cold snap, when evrything got cold, and then a warm westerly blew in from the Atlantic. Fortunately my current workshop is in the garage adjacent to the house and contains the balanced flue central heating boiler. Not always warm, but always rust free.

[Peter G. ShawParticipant @peterg-shaw75338]

I always thought I had plenty of ventilation – soffits etc don’t fit very well and the roller door lets plenty air through, especially in the teeth of even a moderate SW wind. Rear door opens into a porch which was deliberately built to allow plenty of ventilation while giving protection from the wilder elements, although I do take the point about an air change on closing down after a session. Trouble is, to do that will involve raising the garage door slightly which then becomes an open invitation to the local cats, and next doors dog. I’ve even had a cat come in the house through two open doors on hot summer days whilst I have been on the computer! Blasted nuisance!

 

Regards,

 

Peter G. Shaw

[MichaelRParticipant @michaelr]

Here’s a thought, instead of covering the machines with a sheet or plastic bag how about using a Electric blanket, set on the lowest setting this would keep condensation away.

Stick.

[Cyril BonnettParticipant @cyrilbonnett24790]

I went to have a look at a coronet minor ‘ten in one’ offered for sale a few years ago, on arrival I was told that it had been purchased new but because of ill health never used, situated in a garage it was covered with blankets, carpets and polyethene sheet, quite a load to remove, despite it having been oiled the owner looked quite shaken when eventually all the ‘protection had been removed, the machine was covered in a thick layer of fine red rust. The chrome on the lathe ‘way’ was gone and it was badly corroded as was the alloy parts.

Living in the highlands not far from the sea I have to deal with a salt laden atmosphere which at times leaves a coating of salt on our windows, this means that prevention of rust is a continual battle.

Plenty of ventilation in my wooden workshop/shed along with loose bubble wrap sheets and a light coating of wd40, or if I’ve spent all my pocket money, an oil and petrol combination seems to do the trick, mind you the price of those is comparable to that of the wd40 when I come to think of it.

Cyril

[PatParticipant @pat]

Covering a machine with a heavy cotton sheet has always been regarded as good practice and it certainly helps reduce condensation due to diurnal cycling of the workshop temperature assuming the work space is not a constant temperature.

 

The use of a small heater under the bed of the machine also helps and these were sold as damp chasers. 50 mm dia tubular heaters are still available but are a bit more bulky than the damp chasing rods that were common a few years ago.

 

Now I have retired I have set up a small machine shop in the single skin double garage and use two types of dehumidifier with controls to catch any excess humidity. The reason for two types of dehumidifier is simply that the compressor sort have a high extraction rate provided the ambient temperature is over 10 Centigrade and have the other advantage that they can be controlled directly by a time switch and humidity sensor. The sort that use a rotating desiccant drum work well down to 3 Centigrade but require internal modification if they are used with any form of external switch as their fan and drum motor must run on for several minutes after the internal heater is turned off in order to save overheating the drum. I burnt one drum in finding this out! The switch gear powers up the dehumidifier when the RH is above 75% and a simple changeover air con thermostat is used to switch the compressor type on if the temperature is above 10 Centigrade or the desiccant type if under 10 centigrade. A further thermostat cuts the dehumidifiers out if the temperature falls below – 3 centigrade. As stated the desicant type has been modified for external switching running the drum and fan for 5 minutes after switching off the internal drying heater.

 

The machines are covered in heavy twill cotton sheets (Axminster Tools) and are cleaned with WD40 bulk liquid brushed on if not going to be used for a few days. So far no rust problems after three winters but there is a brown stain on some surfaces that wipes off with turps / white spirit. I do not use paraffin as this causes parts to rust where as turps does not.

 

 

The electricity consumption averages at less than 150 watts during the winter and the RH is less than 70% .

 

I like the idea of using an electric blanket provided it is electrically sound and not a refugee from the tip. However the use of polythene or non absorbent sheeting will make condensation problems worse.

 

Hope this helps avoid the rust bug – Regards – Pat

 

 

Edited By Pat on 06/07/2011 12:11:34

Edited By Pat on 06/07/2011 12:12:50

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