Rusted bits

Síle · Aug 21, 2008

I'm not sure if this is the right forum for this.. but I'm going to go for it anyway.

Before going on away for two weeks, I cleared my darkroom, washed down the sink and closed up all my chemicals. When I got home the metal on the enlarger head and metal on the ring around my lenses were all rusted. I also have some grips holding up the enlarger head (don't ask) and they too are completely rusted over.

What did I do wrong? There are some photo's of my darkshed(there was a url link here which no longer exists), if anyone can shed (no pun intended) any light on what might have happened I would be very grateful!

Thanks...

DWThomas · Aug 21, 2008

Sounds as though high humidity and temperature variations with the placed closed up may have resulted in condensation? You might consider a small dehumidifier to dry the place a bit when you're not around -- or at least a hygrometer to see if the humidity is indeed running high -- say greater than 60%.

DaveT

nsurit · Aug 21, 2008

Doesn't look as if there is much in the way of ventilation. Would a light tight ventilation louver and a corresponding vent fan help? With all the cleaning you might have built up the humidity and then it was trapped. Bill Barber

Nicholas Lindan · Aug 21, 2008

Síle said:
going on away for two weeks ... metal on the enlarger head and metal on the ring around my lenses were all rusted.

You need to have air circulating through the shed. You need an air exhaust vent in the roof and an air intake near ground level. Ideally you would have a fan running most of the time - they make solar powered exhaust fans, but a small muffin fan only takes a few watts to run - figure $0.03 / day for the electricity Vs $0.30 / day for interest on $100 worth of solar panels. Just about always the more expensive alternative is also the most polluting after _all_ the factors are added in.

pentaxuser · Aug 21, 2008

I don't think humidity alone could account for it. The humidity in my house is never less than 60% and most of this summer has been running at over 70%. In the U.K. and the Republic we live in a high humidity climate. Nothing has rusted in my darkroom which is a converted bedroom. Had it been the winter then the sudden drop in temp in an unheated shed combined with wet weather over a two week period might have accounted for it but even then the rust seems to have formed very quickly. However it was the summer and in the whole of Ireland this summer, like the whole of the U.K. the temp drop from night to day has been unusually small.

Is it possible that the rust was forming unnoticed before you went away and were the rusted parts bare metal? Was there evidence of serious condensation in the shed on your return? It's puzzling.

Dave Miller's darkroom is a shed. He may be able to shed some light on your problem, especially if he has also been away on holiday.

Anyway we could theorise to the cows come home but in practical terms a dehumidifier is likely to be the answer, even if we never get to the why . There's no doubt that if humidity can be kept low enough like the Arizona desert then rust almost ceases completely. This might be difficult to achieve in Ireland but shouldn't be necessary to keep things rust and damp free .

A heating engineer might be able to advise on the size of the dehumidifier needed to reduce the humidity enough. This is going to sound like me being a "dismal Jimmy" but if it is that high to cause these problems after two weeks, I'd want to check my enlarger lens to ensure condensation can't enter there and potentially cause fungus. Photo paper might also fare badly if stored there. On the other hand if you've had paper in there for months and it is showing no signs of the wavy warping that occurs with paper in books etc in very damp conditions, it would seem to indicate that normally dampness isn't a problem.

I hope it turns out to be manageable and the solution is relatively inexpensive.

pentaxuser

fotch · Aug 21, 2008

In most if not all areas in the USA, a house is built with ventilation in the roof, above the ceiling (and insulation).

The ceiling (above the drywall or plaster) will have a vapor barrier, then the insulation, then the vented roof. This includes vaulted ceilings (which is like this darkroom), this system is still used. There are other ways of building but I would venture a guess, this is the most used.

The walls are similar in that you have the drywall, vapor barrier, insulation, air space but usually no ventilation.

If the house is not built over a basement, rather, a crawl space, it will also be similar to a point, with the roof ventilation system. If on a slab, it should also have a vapor shield.

Don't know if it is different in other areas and don't know why it would differ if is does. Anyway, I cannot tell from the photos, however, it looks like it has no vapor barrier-ventilation system. Does it?

A look at the local building codes would probably state what is needed for your area.

In anycase, there might be a problem with mold so this should be of concern also.

Hope this helps
Jim

Paul Goutiere · Aug 21, 2008

It is a really good looking "darkshed" I'm impressed.

The first thing I'd like to ask, however, is;
Is it heated?
Is the heat on 24/7?
External ventilation?

Any great variance in temperature will cause condensation. Vapors from acetic acid and other chemicals are aquiescent and will be attracted to the condensation and hurry the
corrosion which may be inevitable anyway.

Trust me!

Ian Grant · Aug 22, 2008

It's ventilation and humidity, I had similar problems with a small darkroom in the UK and it ruined my original Durst, I was able to re-build the 5x4. It makes sense not to keep your enlarger lenses in the darkroom, take them into the house after each session.

A small ventilation fan should make a very significant difference.

Ian

Dave Miller · Aug 22, 2008

You will get quite violent temperature swings in an unheated shed, even a well insulated one. This may allow condensation to form, and will almost certainly allow the relative humidity to reach 100%, hence rusting. The recommendation to ventilate it effectively is a good one. I have a small fan circulation fan running continuously in mine, plus a small heater maintaining a minimum temperature of 18C.

Síle · Aug 22, 2008

Thank you all for taking the time to reply in depth to try solve my puzzle. The general consensus seems to be condensation is the culprit, which I will admit at the beginning I was reluctant to concede could be the problem.
As Pentaxuser said, Ireland is not a country of temperatures extremes or indeed great heat. particularly this damp summer, so I had initially discounted that as a possibility. Also when I got home there was no residue of condensation on any surfaces in the shed and no signs of dampness whatsoever. Some paper ( lying on the counter top beside the enlarger) is fine. Also there was absolutely no signs of rust on anything before I left. Another weird thing is that there are two vice grips holding the enlarger head in place, and the one on the top was fine but for a few spots and the one about 10 inches below was completely rusted over.
Paul I do have heating in there in the form of a small plug in electric heater, but as yet I have had little use for it, and have turned it on twice briefly since the completion of the shed in March. I think I will take Ian's advice and take the lenses in with me each time I'm out there.
I've bought two louvred air vents (thanks for the suggestion Nsurit) which I'm going to stick in today and hope that it helps in the short term. But will look into an electric fan in the long term as Nicholas suggests.
If I could ask one more thing.. What is the best way to deal with what's happened.. should I take out everything and sand and wipe down all surfaces affected? And if so, with what?

Thanks a million again to everyone for the advice and suggestions.

Mick Fagan · Aug 22, 2008

Síle, last night I was at a friend's place in his workshop, I chastised him for the condition of his panel saw bench (for cutting timber).

The saw bench top is cast iron and it had rusted over with a fine even layer of fresh rust. He told me that this was a normal occurrence in his garage and proceeded to remove the rust by spraying the the rust areas with WD40, allowing it to sit for about a minute, then rubbing the surface with a stainless steel wool. Like the ones you use for scrubbing pots and pans.

I watched as a slurry was formed, he then proceeded to wipe off the rust and WD40 with a rag. I was quite amazed at just how effective this procedure was.

I have used various methods at removing surface rust, but this was one of the easiest methods I have seen in years. You could go to a hardware store and look at the various specialist rust removal products as well.

With my workshop tools, especially my handsaws, I use a neutral furniture wax to keep surface rust at bay on bare metal surfaces, works a treat.

Mick.

Martin Aislabie · Aug 22, 2008

As Dave said, you get quite abrupt temperature swings in any thin skinned shed.

Perhaps counter-inuatively you get most condensation on internal objects when the temperature in the shed warms up - as the interior furniture stays cool due to thermal inertia .

This is most likely to occur in warm weather that is a mixture of strong sunshine and heavy showers

However, I am sure you are not THAT interested in Thermodynamics and/or HVAC

What you need to do is introduce through flow ventilation - louvres and flaps will be enough - just leave them ajar when your not in there - you could add fly screens to prevent too many "freinds" from joining you

As Dave also says you could add a permanent ventilation fan to help manage humidity levels and a small heater to prevent temperatures dropping too low

You can also paint the outside of the shed white - reflects solar load to keep the temp change smaller/slower when the sun comes out

Also think about who water proof your shed is - do the roof and walls weep a little & do you get damp/moisture rising up from the ground.

If you still have condensation problems after sorting out the ventilation and the moisture proofing sorted out you might want to think about insulating the shed to avoid excessive temperature swings

Martin

Síle · Aug 22, 2008

Mick thank you, that sounds like a great way to get rid of the rust and not too difficult a way either! It should also help to protect them in the future. Although going away for 2 weeks is a once a year occasion, I will be wary now of further rusting, mould and fungus! Hopefully it will stop at the rust.

Martin thank you for the brief lesson in thermodynamics, it was truly enlightening! I think there must be something in what you said.. "This is most likely to occur in warm weather that is a mixture of strong sunshine and heavy showers" as this has been one of the wettest summers ever, but there have been (very) brief periods of strong sunshine in between. I do hope to do as Dave suggested and eventually fit a permanent fan, but for now, the louvred vents will just have to do.

As a complete aside.. I have to add.. it never ceases to amaze me of the sheer wealth of knowledge and expertise in all fields lurking in the halls of Apug, it really is fantastic. Thanks again everyone.

pentaxuser · Aug 22, 2008

Sile. I thnk you said that the shed has only been operational since Spring and you may not have had any really long cold spells but uninsulated wooden sheds will get very cold in Winter and without insulation any heating is going to be quickly lost through the walls. I've been in my garden shed for as little as 15 mins in Dec/Jan and I wouldn't like to spend an hour or more there. It is single skin and unheated. I'd like it even less if I had to pay to keep it warm as a single skin shed.

Unless they float Ireland and move it about a 1000 miles South( Gibraltar as a minimum) by say October I'd consider insulation seriously.

pentaxuser

Síle · Aug 23, 2008

Pentaxuser,

The shed has just been operational since Spring, and thankfully there haven't been terrible temperature lows as of yet.. But, and I'm not so sure how well you can see from the photo's, the shed itself is cladded on the inside with 8mm thick boards, and the floor is insulated with a double floor laid on top (to be sure to be sure...)...
That coupled with my trusty plug in heater should hopefully see me through even the coldest Irish winters and means I won't need my thermal undies!

ic-racer · Aug 23, 2008

Interesting you have posted this issue as I have followed a number of these darkroom shed posts and thought to myself 'you could never do that in the Midwest USA' The humidity, mildew and rust would destroy all the equipment.

Bob-D659 · Aug 23, 2008

A rub down with steel wool and oil will remove most of the rust. A bath of naval jelly (phosphoric acid) rust remover works as well. Just make sure to clean it off and coat all bare metal surfaces with a light coating of oil.

Vaughn · Aug 23, 2008

Probably not the problem, but there are chemicals used in making photographic solutions that if they escape into the air will corrode metal. There is one in particular, but I can't remember its name.

So, are you storing raw chemicals in your darkroom -- if yes, you might make sure all are well sealed.

Vaughn

glbeas · Aug 24, 2008

Vaughn has a point. Fixer powder is hygroscopic, meaning it'll suck water out of the air and eventually liquify if the humidity is high enough. Mix the powders outside to avoid contamination if you can. I've heard of an instance where an electric outlet got dusted with fixer powder at some point and after a week or so it shorted and burned out from the salty moisture on it and in it.

Drew B. · Aug 24, 2008

Síle;670257) What did I do wrong? Thanks...[/QUOTE said:
yup...ventilation is the culprit. Hey, when we all come to Ireland, can we use your darkroom?

Reinhold · Aug 24, 2008

Síle,

As others have noted, temperature swings can condense the humidity on cooler metal abjects. Every once in a while conditions are just right, and it everythig gets all "sweaty".

I have an unheated machine shop with the same problem

My solution is to use "Goldenrod dehumidifiers" under a cloth sheet which I toss over my machines when I'm away.
They keep the temperature from dropping to the dew point under those "blankets" covering my equipment.
These heaters are used extensivly by the marine industry to control rampant humidity in boats.

Here's some info on the Goldenrod units... http://www.drytheair.com/xcart/store/catalog/category_264_Electric_Air_Dehumidifiers_page_1.html

Another approach for heating during the upcoming winter months is an oil-filled space heater. They are relatively low wattage, and very safe when unattended. The heat is gentle, and not prone to the wild swings of fan-forced space heaters.

If I were in your darkshed, I would absolutly have one of these... http://www.lakewoodeng.com/html/list_oilfilled.html

By the way...
Verrrry nice darkshed.

Reinhold

www.classicBWphoto.com

Síle · Aug 24, 2008

I see an afternoon of wire wool, WD40 and Petroleum jelly in my future.. Which sounds like more fun than I know it will be!
Thanks for all the advice, I had my suspicions, and it appears they were well founded. Vaughn I don't store dry chemicals in there, just bottled ones, and would be wary of every doing so after reading glbeas story!
Reinhold, thank you for the links and compliments on my Darkshed. I'll look into those for the future, it does seem like a great idea, and the heater... is exactly the same as the one I have in there! I did something right!!
Drew... come on over, but bring your wire wool

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