plastic or cotton covers for machines

Some people advocate using a cotton machine cover rather than a plastic one, but I have never been convinced of the wisdom of this. Is there any real scientific evidence that would back up this idea. If the cotton only absorbed moisture and as a result kept the machine dry I could see the logic, but surely damp cotton will also release moisture to the detriment of the machine. What do others think?


Doug

Doug, I live 50 meters from the edge of the Atlantic, and have a very high , salty, humid environment.

We have regular strong, wet westerly winds from the ocean, and sometimes dry wind from the east over the sandy desert, so I get sand and dust as well! I always covered my machines with heavy plastic and then a cotton cover, like an old bed sheet or similar. The I discovered these semi-waterproof Car 'shade' covers - they are made from a thin but very tough material coated/impregnated with a plastic or rubber coating, similar to a semi-waterproof raincoat. They also have an elastic around the periphery.

I obtained a medium motorcycle size for the small lathe, and a mid size Quadbike one each for the big lathe and the two milling machines. They work a treat - quick to fit, do not tear easily, and form a nice skirt down to the base of the machine.

Joe

Joseph, yes, I used them on both motorbike and kit car when I needed to store them outside, before we moved house and I gained garage space.
I can confirm they work well, and are also breathable to an extent.

For UK readers, an easy source is either Aldi or Lidl when they have the motorcycling offers on; normally about £9-10 each

Bill

Edited By peak4 on 06/01/2019 14:56:40

Plastic vs Cotton depends on what your problem is. Both inhibit air-flow around the machine and keep damp air away, or at least stop it circulating. Both are potentially helpful with various pros and cons. Cotton is a better insulator, which tends to help the machine underneath at a steady temperature. A plastic cover can trap wet air in contact with the machine, or collect condensation on the inside and drip water on to the machine. Cotton being porous and a good thermal insulator won't collect condensation, but it will soak it up.

One way of choosing is to decide if your damp problem is more like a shed roof or feet. A shed subject to rain and mist needs an impermeable barrier to keep wet out. Plastic socks would be very bad for your feet. They trap sweat, you smell bad and get foot rot.

In my generally dry UK workshop, in a well-insulated part of the house, cotton is better because it doesn't trap condensation. At the Nambian seaside Joe has a very different problem; for him plastic is best. I suspect for a lot of people either would do, or even not bothering.

When dealing with condensation I feel it's best to eliminate root causes if you can - stop water getting in or remove it with ventilation or a dehumidifier and inhibit the temperature swings that encourage condensation on cold metal surfaces. (A blanket might be better than cotton sheet.)

Dave

I use old towels and lots of them and have no rust on my machines.Rapid temperature swings do cause condensation.I have a dehumidifier which is switched on economy seven from 1am to 8am and I don't heat the workshop as I worked outside for 50 years and find a coat over my overalls is quite comfertable and therefore it's only my breath thats a problem.

Frank

my machines are wrapped in old Duvet's and blankets.......

underneath each machine (7) I keep an 11watt curly whirly bulb running 24x7...never any rust ......the bulbs are on from the end Sept till mid march........

My place is a 17th century watermill........leave the covers off just 1 night and u get rust.......

when my water soluble suds liquid is finished I'll be using 40grade (I think) Hydraulic oil for coolant.......

Condensation forms far more readily on smooth surfaces, such as plastic sheet and tin shed roofs. As Dave says above "In my generally dry UK workshop, in a well-insulated part of the house, cotton is better because it doesn't trap condensation." + it can evaporate off. Me? in my part integral garage I don't cover anything and don't get rust as the temperature swings are too slow.

BTW Ikea still sell a very cheap polyester single quilt for the price of a pint, for an extra quid you can get a double, only 4 tog.

Lots of different ideas there, I do like the motor cycle covers that Joe illustrated-must keep an eye out for them . I have been using the original Myford plastic cover for 20 odd years and it is now falling apart so I will need a replacement soon. I have a well insulated workshop and the plastic cover has served well so I will probably stick to plastic, but as Dave- the Silly old Duffer- said it seems to be horses for courses.


Doug

Agree with SOD - at this time of year watch out when warm moist airstream arrives after a very cold spell. In an unheated workshop the heavy machinery may have fallen below freezing point (well below dew point).

If the machinery is below dew point then condensation will form on it and rust non painted / oiled surfaces. If below freezing it gets worse as water being heavier than oil will penetrate below the oil and ice crystals form. Rusting will ensue even if the workshop itself is lightly heated and no condensation on windows. Ambersil make a good protective 'oil' which I find helpful if I cannot get to heat the workshop at the critical time.

If you know such a weather change is about to occur try and get the building heated or put a small tubular heater under your lathe and maybe under your 'precision tool cupboard' also to get these items well above freezing.

The advantage of some steady heating (and dehumidifying) of a workshop is that the building fabric dries out and gives this the capacity to adsorb some of the moisture that infiltrates when a warm moist air mass arrives. (sort of sponge effect)

Yes heating and dehumidifying costs but in many cases that is trivial compared to loss of value of tooling as it goes rusty!

I have a heated shop and my machines are left naked.

In summer I run a dehumidifier.

Much depends on your climate.

In humid climates where condensation is an issue, just a little heat works wonders - every 3degC you raise the air temperature doubles the amount of moisture it will hold, thus Clogs 11 watt bulb is a good idea. Isolating the machine and keeping the air inside the barrier a few degrees warmer than that outside works wonders.

We get quite a bit of rain here. My machines are in attached garage which though not directly heated, stays above outside temp., and in the 30+ tears we've been here I have never had a condensation issue. For preventive purposes I periodically coat all unpainted surfaces with a light film of way oil, or I use a product called Boeshield T-9 - not sure if it is available in the UK. Other moisture displacing compounds like WD40 also work pretty well.....

Tim

My mini-lathe is approaching it's twelve'th birthday. It has zero rust problems.

After use I lightly give the metal parts a mist from an aerosol can of this **LINK** and cover it with a wheelie bin liner, topped off with a cotton bedsheet. Sometimes I have noticed that the sheet feels a little damp when I remove it, but underneath, all's well.

Admittedly the air temperature in my part of Australia seldom goes below zero, but the humidity and summer temperatures are really hot (44°C /111°F) here last week so cause their own share of problems. (Sweat dripping onto the ways has to be wiped off immediately or it will leave a mark)

The lanolin based oil seems to help a lot (never seen a rusty sheep), it's safe to use and also makes a great cutting fluid for aluminium if I run out of kero.

Only downside is that I once used some to flush a model diesel engine, flicked the prop and away it went!

* Danny M *

Duplicate

Edited By Danny M2Z on 07/01/2019 05:18:20

Dave, your post set me thinking a bit more on the issues I had with rust here in Namibia. I have two shops, one only metal working and one that is mostly woodwork. In the latter is a large bandsaw and tablesaw ( table abt 1.5mx1m). As wood and oiled metal surfaces don't really mix, I started by not oiling these machines. I covered first with an old duvet cover, cotton, then a plastic cover to still keep the sand/silica/mica dust from the tables. After a week or two, I found my hand covered in a red/brown fine powder after wiping the tables with the hand. I cleaned off the fine rust, which covered the entire metal surface, and then swapped the plastic and and duvet, ie, plastic first, and the rust would still appear, but in patches and only after 4 to 6 weeks. The patches were noted to be where the plastic did not contact the table fully.

I think the cloth cover contained enough 'water' absorbed from the humid air, and trapping that between the metals surface and plastic sheet was bad. Likewise, trapping pockets of humid air between the plastic sheet and the metal surface was as bad.

So now I wipe down the woodwork machines with a 50:50 mix of turps and two stroke oil, and cover with plastic, and a quick clean before doing wood seems OK.

So, as you say, there is no 'better' solution - keep falling condensation from the machines, keep the machines above the dewpoint temp (Clog's idea of a very low wattage lamp under the was, with a car cover might work well), and keep them oiled. When I still lived in South Africa ( Johannesburg) humidity was low, temps inside the shop were never below 10-12deg in winter, and the building was brick and steel roofing with an insulated ceiling and the machines stood open with no problems, so each situation needs to be resolved on it merits..

Joe

I think MX3, WD40 and Ambersil corrosion inhibitor are all similar in that they incorporate special oils that displace water (heavier than water? Fish based oil?). Ambersil is used in the marine industry and dries to leave a thin protective film which is much more effective than WD40 but ay be a bit tacky for coating finest instruments like micrometer threads. It cleans off readily with petrol based solvents / white spirit / oil. I use Ambersil on all my heavier and little used tooling ( vertical slides, change wheels, spare chucks, big boring bars etc) where I don't want rust damage.

I have found that cloth covers actually aggravate rust when they get damp unless the surface below and the cloth itself are oiled. I lay an oily rage over machine slides when not in use as it also catches and holds dust and doubles as a wipe over having brushed off swarf at the end of a session. I then have a thicker cover over the lathe but do not protect the milling machine other than the oily rag over the table.

The external walls of my workshop are old solid brick and items laid against them on the North wall will rust unless a decent air gap is left under and behind to let the heat in and the moisture out. The combination of a small fan to move air around in the worst area and a dehumidifier nearby effectively does the trick and makes no noticeable difference to our electricity bill.

My workshop is an amalgamation of two buildings and is constructed from part concrete block work walls and timber frame with weatherboard exterior. The block work is not insulated, just painted with polyurethane floor paint on the inside to prevent damp penetration, the weatherboarding which faces the prevailing weather, is insulated internally with 100 mm of Celotex. The roof is a flat roof of OSB sheets, covered with 2 layers of torched on felt, insulated internally with 50 mm of Celotex. During the winter months I run a small oil filled electric radiator, 24 hrs a day on a low setting to provide background heat throughout, also I run a dehumidifier during the off peak hours, 1.00 am to 8.00 am, 365 days a year. The dehumidifier is wall mounted and has a permanent drain which is led out through the wall so no emptying is required. I picked up the dehumidifier from an online sale a number of years ago for about £100 and it has proved invaluable. I never have to cover my machines and to date have not suffered any rust problems on the machines or tools, despite the fact that we are only about a mile from the sea. I think the reason for success is due to keeping the temperature reasonably constant throughout the winter, this is achieved by the insulation stabilising the temperature and preventing large temperature fluctuations. I think every workshop will behave differently and I believe you have to experiment to find what solutions fit your individual circumstances.

Dave W

Did you try wax of any kind?

I have a 1970's workshop with single wall brick , concrete floor and 100mm composite roofing, and have never had a problem with rust on my tools or machinery. My various machines are cover with covers made from a 'retired' caravan awning!

ega,

I did try wax - first a beeswax type, which was no good - well, it prevented rust, but the wood tended to stick or judder along the waxed surface after a while, and was not easy to pass smoothly through the saw blade. The beeswax was too soft.

I then tried a carnauba wax which buffs up hard, but you have to buff it - leaving it just wiped on it dries to a whitish almost powdery surface, and has strong 'stiction' . Also the buffed wax would be abraded and torn away when chips and sawdust was scraped over the surface, but not visible, and so small rust lines would form if I did not re-wax. And re-waxing carnauba to a sheen is hard work!

Joe

Joe

As you would expect there are other, purpose made waxes, with or without silicone. One, not tried by me, is:

https://www.axminster.co.uk/axminster-machine-wax-400g-101582

I appreciate that there is no local branch and that your environment is a mixed blessing!

Another relevant item available here in the UK from the Halfords cycle shops is a cover which they sell as "bike pyjamas"; just the right shape for a long machine like a planer/thicknesser.

Edited By ega on 11/01/2019 00:22:29