Rust in Workshop

Brad / Dave,

Quite probably the gas heaters are your problem. They give off copious quantities of water vapour while they heat the air and leave your machines cold. When you turn them off, the air cools and the moisture in the air condenses on the machines. Gas heaters are a BAD IDEA in workshops unless they are of the room sealed variety that vent directly outside.

Can I suggest that you mount a 60watt bulb in the base of each machine and leave them on all the time you are not using the machine. This keeps the machine a degree or so above the air temp thus stopping the condensation.

AWEM

Assuming that the shed is reasonably well sealed, get a dehumidifier and pipe the drain pipe to the outside. Run the dehumidifier until the shed has dried out. After that it should cycle on and off and cost less.

Are you parking cars in there as well? If so, the dehumidifier is vital. If the building isn't well sealed then you will have issues at this time of year. The dehumidifier will help, but it'll cost more to run.

Mark Rand RTFM

Problem I found was that the de-humidifier didn't work when most needed, ie during the winter months. The absolute worse thing to do was to get the shop nice and warm on a cold winters night, then power down and leave the place for a week. 90% of my rust problem went away when I stopped heating the workshop and put up with the cold. I will try Andrews' trick and see if that solves the rest. Used to do that with the rabbit during cold spells, never thought to use it on the machines!

Steve

Atmospheric moisture is bad enough for rust, but you are adding to it with the gas heaters. All heaters with a flame, whether gas, oil, paraffin, or wood create water as a product of combustion, so unless the heater has a flue to the exterior of the building you are causing the rust by warming it. That may seem contradictory but it's true.

The three solutions are to get electric heaters, get flued gas heaters, or get a de-humidifier. I use the last option as it is cheaper to run than electric heating. The only drawback with cheap de-humidifiers is that they rely on ambient temperature to defrost, hence the defrosting doesn't work below about 5º. That really isn't a problem because at these temperatures (such as we have overnight at the moment in the south) the realative humidity is very low, so it can be switched off without any significant risk of rust.

Cliff Coggin

Dave I have a 6m square shed built with 4x2 walls and 6" joists for the roof. It is split in two down the centre with a 4x2 stud wall.One side ( my workshop) is insulated with 100mm rockwool on all walls and the roof. The other side is not insulated and has an aluminium garage door. The workshop has two electric heaters. I only switch on when I am there and it is too cold. I have no problem with rust at all in the workshop side but it does occur in the other half. I believe that the insulation keeps the temperature more stable and that prevents condensation forming on cold ( cooler) objects. If you put a mirror in the freezer then bring it out into the warm room condensation immediately forms on it. But if you leave the mirror in the room so that it changes temperature as the room temperature changes it will stay clear. As long as the shed temperature changes slowly enough to prevent the larger mass of the machines from becoming fridge mirrors I think you will avoid surface rust. This works for me but if you think I have done something wrong then there is always WD40. Regards Alan

Hi.

That's exactly right with the ' normal ' refrigerating dehumidifiers - efficiency drops like a stone at much below 15C or so.

I've bought myself a desiccant rotor dehumidifier - I was having exactly the sort of problem described in the original post - rust everywhere - and presto, the problem has gone :-) Remarkable quantities of water coming out of the thing...

The desiccant rotor dehumidifiers cost a little more to run (they include a heater as part of the mechanism) but you probably don't also need a heater on anything but the coldest days...

Youra.

At the expense of loosing space think about putting a domestic freezer in the shop. I had to put up with one in an unlined brick garage once and the rust problem was reduced no end. Just simple lubrication took care of the rest.

Remember for a freezer to work it has to give out heat and if it keeps the dew point at bay then it's doing it's job.

Insulation is the only real answer.

.

-- Regards,

John Stevenson Nottingham, England.

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Do you think that just insulating the roof with fibreglass and plasterboard do the trick? (probably together with a dehumidifier?) I can't line the walls as I can't afford to loose the space. Would 4" breezeblocks be sufficient to avoid lining the walls? Brad

A freezer does work for me in a 22x12 foot garage, the only rusting occurs with bits laying on the floor for any length of(long)time

Brad/Dave?

You have me a bit confused with your "breezeblock" question. My experience with 4" breezeblock single skin walls is no they are not sufficient even when well sealed. However you don't need a great thickness of insulation and in my first workshop (single block garage

10x20) the rust problem was mainly solved with a plastic membrane, 1" of polystyrene sheet and an inner wall of 1/2" ply so the total thinkness was less than 2" but it was very effective. The roof definitely needs doing but remember to allow for air circulation above the insulation or you will get condensation dripping from the roof. Having some ventilation is also helpful as even just you working in the shop will introduce enough moisture to create a problem.

Although I live less than a mile from the coast and park a small car in there, I don't have a problem with rusting. A combination of some gentle background heating (dry, when it is cold I use a small oil filled electric radiator with a thermostatic control set low), a cheap de-humidifier and oiling the "bright" bits of the machines with Nuto

32 or similar light machine oil keeps my stuff clean and bright. I banished WD 40 from my workshop years ago and now only use it on lawn mowers and things that don't really matter and only then to remove any moisture on them before oiling them properly - it is a better cleaner than it is a protective.

regards

Keith

What you need is a nice draughty workshop, with a bit of air movement through there, and you'll have no problems. Can be a bit parky beavering away there in the winter though. Works for me anyway.

Peter

A very similar solution worked for me - fixed vertical battens to wall, insulated gap created with rockwool. faced with polythene dpm sheet and lined with chipboard. Similar approach for roof. Temperature is remarkably stable summer and winter. Heat with convector heater thermostated to 12-14C - it doesn't switch in very often even in winter provided the door isn't left open. Had to wall off the steel up and over door as that would negate insulating the rest. Non oiled bright surfaces will develop a very thin patina of rust after a moist winter - oiled surfaces don't rust at all.