This was my very first brass paraffin stove purchase, way back in 2005 A Phoebus fixed leg n.1 My first attempt at cleaning it up produced this .. (note the non original Primus filler cap) ... however it came at a very high price. In my innocent eagerness, I left the stove soaking in a vinegar bath overnight. After much help from Handi Albert (where are you Albert ?) it turned out like this That's a BIG 5/6 pint kettle looking right at home But the joy was short lived. Albert had repaired 5 or 6 hair line crack that had appeared in the tank ... that vinegar bath .. and after a few more weeks with it burning, more hair line cracks appeared. The tank now seeps fuel in 3 places when pressurised, so I've decided to 'chalk it up' to experience and retire the Phoebus to the top shelf in the garage. Still, it got me well on the road to this stove collecting lark (d@mn Phoebus ), so I'll always treasure it.
Hi Spudz. How is this for coincidence? I actually have a fourth Phoebus No. 1, a fixed leg two-pint stove which I have not yet fully restored or photographed. I bought the stove, via Ebay in May 2005, from Bergamo, Northern Italy. I had to replace the whole NRV on the air-pump, and I then had the stove operating. I still need to repair a "weep" of paraffin from one position on the bottom tank seam. However, hope springs eternal and these are old stoves. I guess that Austria was a nearby supplier of quality stoves for Northern Italians in the 1930s. Best Regards, Kerophile.
Hi Prindel, Is it a two-pint stove you are interested in or specifically an old Phoebus.? If you want a usable stove you are probably better with a more modern, 40 year-old Swedish model, such as a Primus, Optimus or Svea. I am somewhat disillusioned with our mutual Postal Services at present but if you are looking for one of these Swedish Quality stoves, and you want to risk our shipping services send me a PM. Regards, Kerophile.
Hi Spudz So are you saying that an overnight soaking in vinegar (is that malt, spirit, wine, cider, or what?) resulted in the cracks?
I think it is bad to over do the vinegar, well known to chemically stress spun and stamped brass, but it may also have had a lot more to do with how it was annealed at the factory. There are a couple of lamp and lantern companies known for poor annealing of their products for defined periods of time and many, or even most, of their founts from those time periods have or get stress cracks. Regards, Ed
my emphasis I guess I did say that, but perhaps I shouldn't have. I'm no metallurgist, but there has been some advice on this Forum regarding overdoing the vinegar bath treatment (white wine in this case), I'm just putting 2 & 2 together and keeping fit by jumping to conclusions. It was very disheartening to 'see' hair line cracks 'appear' before my eyes as the stove tank was put under pressure. One moment everything was fine, then .. bubble bubble bubble, as fuel began to weep from a crack. Like most things in life, I suppose even white wine vinegar is best 'taken' in moderation.
Hi, I am a Metallurgist.... They do say that if you are a Medical Doctor, never admit to it at parties as if you do everyone will want a free consultation. Nothing is simple and there is a mountain of literature on stress corrosion cracking (SCC), particularly that of Brass. Here is a review article on cleaning brass I found on a quick search: http://www.abbeyclock.com/polish.html This covers many of the basics of metal cleaning and corrosion. Prindel is correct when he says that inadequate annealing ( stress-relief) of tanks and fonts, during the manufacturing process, is implicated in Stress Corrosion Cracking. The residual stresses locked up in the atomic lattice of the metal provide the driving force for crack initiation and growth during subsequent corrosion. Similarly if the metal is stressed by an applied load during the corrosion process, cracking can occur. The nature of the corroding substance is also important. Alpha brass ( the material used to make stove tanks) is particularly susceptible to SCC when exposed to ammonia solutions or mercuric salt solutions ( and the latter is used in a standard test for susceptibility). However many corrosive solutions can crack a metal already prone to SCC. In the case of Spudz Phoebus tank, I believe it highly likely that it failed as a result of SCC. It is probable that there was a high degree of residual stress in the tank, probably from the time when it was manufactured. The tank can stand this level of strass as a standing load indefinitely under normal conditions, however, once exposed to a suitable corrosive agent, rapid SCC occurred. It is the simultaneous action of stress and corrosion which causes the problem. The metal can handle any one of these, but not both. There are two secondary issues to consider with Spudz experience, firstly the over-exposure to the vinegar, and secondly the use of wine vinegar. If a tank is susceptible to SCC a longer exposure to the corrosive solution could be a factor, but not the most important. Brass tanks can crack under the action of condensed moisture layers if these contain ammonia ions. If you must use vinegar, used the cheapest distilled vinegar (Acetic acid is available in grocery stores as white distilled vinegar at a standard concentration of 5% acetic acid by volume.) not brown vinegar, malt vinegar, wine vinegar or vinegar made from fruit juices. The latter are all complex solutions: yes they do contain acetic acid but also a lot of other compounds, some of which could be very corrosive. As I said at the beginning, nothing is simple and I cannot recommend a "safe" cleaning solution for old stoves and lamps. We are dealing very often with old items which were manufactured with different materials and methods that would be used nowadays. There would also be variabilty in the quality of manufacture, between manufacturers and even within the same factory ( the Friday afternoon stove). If a particular stove does have locked-in residual stresses it is susceptible to SCC and this can occur in many metal cleaning solutions, or even with liquid layers condensed on the surface. There is nothing you can do about it. Personally I use a solution of Citric acid in water to clean oxide films from old brass items. However, I would not be too surprised if it too had the ability to crack a stove tank with high levels of residual stress. As you can see there is a scientific argument for leaving the protective oxide layer as is. It has to be a personal choice. Regards, Kerophile.
Hello, Spudz, Kerophile, and All, Don't know if you remember, but a while back, I ended up with what appeared to be a fantastic Hipolito stove, only to find it full of stress cracks on the tank!! Here are a few photos that have been posted here before: Needless to say, finding this otherwise lovely stove rampant with stress cracks was not a happy thing for me!! But, I still appreciate it's beauty, and the price I paid, even with shipping from the UK, was not too high. So, I immediately retired it, and for the rest of it's life, it will be a "looking at stove", and not a user. Them's the breaks, eh.... or, in this case, the stress cracks!! Your first Phoebus is still an important and valuable stove, Spudz, especially to you!! That's the most important thing, really. View it with pride and tenderness, Lad!! Take care, and God Bless! Every Good Wish, Doc Mark
Hi Doc, Cracking ( sorry) photographs of the SCC phenomenon, absolutely text-book quality. Polish the stove, give is a coat of clear lacquer and you have a nice display model. I don't believe that any manufacturer was immune from this problem as it is an inherent weakness of the Alpha brasses used in tank manufacture. The temptation for the designer is to leave the components "half-hard", rather than fully annealed, at the end of manufacture as the strength is higher and they can get away with thinner ( and cheaper) sections. The only practical way of hardening and thereby strengthening these brasses is by cold-working them, unfortunately this leaves them prone to SCC in service. I have found that the otherwise very good Czechoslovakian "Meva" stoves are very prone to SCC. They took thin sections to the ultimate. It made for light stoves but unfortunately left them vulnerable to cracking. Regards, Kerophile.
I knew about the ammonia. That's a reason why I don't really fancy the very common use of Autosol to polish these old articles. I'm not sure if the Autosol do any damage in reality, but I have some indications so I don't take that risk anymore.
Thank you George for an excellent exposition of the problem. I don't think any of my collection has stress cracks, but that is not to say they won't appear in future. After an initial cleaning, and some photographs, I don't tend to clean them again, but even so perhaps it is time to drop the vinegar and look towards citric acid.
Both acetic and citric acids are typical weak organic acids, Keith, and have a similar structure. Each molecule of citric acid has three carboxyl groups whereas acetic molecules have only one, otherwise there's not much to choose between them. My bet would be that they're equally likely to be involved (or not) in stress-cracking. Personally I've always used vinegar for cleaning purposes. My technique is to use a 20-30 minute dip followed by a quick rub-and-rinse between my fingers. Occasionally I find a second 20-30 minute dip is necessary to remove the stubborn stains. I'm not a fan of prolonged immersion in anything. I've only one stove that shows stress-cracking - my Parkinson-Cowan 4-burner - and I suspect that's age-related rather than anything to do with cleaning...
I used to be indecisive, but now I'm not so sure. OK back with the vinegar ! I also use dips of 20 minutes or so, and give them a quick rub over. I do find it is useful to give them a good scrubbing in hot soapy water before, as it gets the greasy gunge off and lets the vinegar really get to work on what's left.
Hi, I found a link today to my forst post on CCS. It was on the subject of stress-corrosion cracking, sometimes also referred to as "Season-cracking" Here it is: Best Regards, Kerophile.
Hi Kerophile, I'm interested in understanding more about the annealing process. From my schoolday metal working I recall heating brass and copper sheet to cherry red prior to any bending or other shaping process to ensure the workpeice was malleable and wouldn't crack. However, we never annealed anything after the shaping process to relieve residual stress. For something like a bowl or other object I guess this isn't too much of an issue. However I made at school, and after school years, several model stationary steam engines - strikes me I might have been advised to have annealed the boilers after initial shaping prior to final assembly? I was lucky enough to have an Uncle (now long deceased) with a really good workshop that enabled me to carry on with that stuff after schooldays for a few years. I made a couple of engines for younger cousins, but suspect they don't still exist (the engines, not the cousins). However, I still have my original school made one somewhere - must dig it out an see if I can revive it! Anyway I digress..... If you were to take something like the major, upper section of a stove tank that had just been shaped (via some sort of press I assume) and then annealed it, would it naturally go out of shape if it wasn't placed in some sort of jig. It would seem to me that this would be the natural order of things, that the piece would want to move out of the desired shape as it is heated and the residual stress is relieved if not being mechanically held to shape? If this is the case then I assume it is a process complication/cost trade off during the manufacturing process that determines this doesn't necessarily occur as a matter of course. Obviously with the use of lead solder it's impossible to heat the completed tank to the required annealing temperature and thereby rely on the increased structural integrity of the complete tank to hold the shape as obviously the solder would melt and the tank would fall to pieces. Any insights on whether any of this logic is valid? Or is it just a load of rubbish?
Hi Bomx4. A lot of what you say makes perfect sense. As in life, all is compromise: I will confine my comments to 70Cu/30Zn brasses because other materials, such as steels, are somewhat different in their hardening behaviour. You can harden and stiffen brass by working, but you lose ductility and make the item prone to possible cracking later. Manufacturers therefore make a choice as to how much "work" or distortion they leave in a finished component. In the case of sheet and wire, you will often see materials being offered as "Fully hard", "half-hard", or annealed. Depending on the final application, the customer makes the choice. If you need to further shape the material you would not buy fully-hard material, as it will crack if you add further work without first annealing. If you are going to use the material in as near delivered shape and size you might buy half or even fully hard material as it will be stiff and you might get away with a thinner, and cheaper section. In the case of classic stoves, Meva, the Czech manufacturer, took the use of thin hard sections to the limit, IMO. Their stoves are light, as they were able to use thin sections, but the material is hard and contains much residual stress, making them very susceptible to stress corrosion cracking. Most of the early Swedish stoves used thick section, fairly soft brass. This made them heavy and probably more expensive in material cost, but they are very resistant to stress cracking. I have seen cracking in some Swedish stoves, but the cracks were often associated with later dings, which would have work-hardened the brass locally. On your point about losing dimensional control when annnealing; Manufacuters would typically anneal once or twice during the working process and then take to final dimensions with a relatively small final work-step. Alternatively they would avoid work hardening all together by "hot-working" the material. In this way the annealing process goes on simultaneously with the working and the material stays relatively soft and ductile. Here endeth the lesson Best Regards, Kerophile
Hi Kerophile, Excellent. That provides the second half of what they taught 13 year old boys at my Secondary Modern School. I guess "heat this first and it'll be easier to work and won't break" is sufficient for a 13 year old in metal working class without getting into the atomic structure of metals! I have an old spirit stove that has classic stress cracking which I managed to silver solder up just so I could see it working once, but I wouldn't really trust it in regular use even though it's not a pressure stove. The tank is made of very thin sheet. Got some pics somewhere - I'll try to dig them out. I used silver solder on the cracks because I had to disassemble and then reassemble the tank using lead solder. However, you could actually see and hear it crack further as I heated it up to silver soldering temperature - was touch and go whether I was able to complete the job successfully but it worked out in the end. I did it from the inside - looks OK from the outside, but Lance would probably have a cow if he saw the inside
Hi Bomx4. Many years ago I had a cracked font on a Vapalux lantern. A friend offered to braze it for me. We both watched with amazement as the crack extended as he brought the area up to temperature. The thermal stresses due to differential thermal expansion were sufficient to propagate the pre-existing crack(s). We never did get a successful seal and I ended up buying a replacment tank from Base Camp. Best Regards, Kerophile.
Here's some photos of my first and only (so far, knock on wood) experience with stress cracks. And sadly, on an early Optimus #1 Traveler. This is *not* the Traveler I posted in the Reference Gallery. I was so happy to have found a second one. I love those little bun feet. I didn't even mind that it had a globby solder repair. Or, that the tank was full of gravel. Or, that the burner was nastily choked up. But this stress crack on the top of the tank And this one on the bottom of the tank made me very sad indeed. Subsequent to taking these photos, I found a patch of interlaced cracks across the multi-lingual stamped lettering on the side of the stove. This one will never again take the pressure that a pressure stove requires for operation. Maybe it would make a good electric lamp. I could just drill some holes in the tank and mount some ports........ Kidding!!! Cheers, Gary
