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why cant you silver solder in the workshop?

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Dave Jones 101/01/2010 17:47:36
85 forum posts
5 photos
I have read in various books/magazines that you are not meant to silver solder indoors as this causes other machinery in the workshop to rust.  With the obvious safety aspects of using that much heat indoors, why does it cause machinery to rust?
Les Jones 101/01/2010 17:58:58
2239 forum posts
153 photos
Hi Dave,
                 I have not seen that recommendation but it does make sense as burning any hydrocarbon (Propane, butane, paraffin etc) produces water vapour and carbon dioxide. The water vapour will increase the humidity and water may condense out on cold metal.
 I suppose this would rule out boiling a kettle to make a cup of tea in the workshop.
DRG MIMechE01/01/2010 18:06:49
6 forum posts
3 photos
Hi Dave
    You will get condensation with a variety of fuels if you were running a paraffin heater to keep warm this dose not mean you should not do it. You just have to clean everything and oil it when you have finished.

Edited By DRG MIMechE on 01/01/2010 18:07:37

Baz01/01/2010 18:34:18
609 forum posts
2 photos
Hi Dave,
         Apart from the condensation that may or may not be caused, I think the real reason is due to the fumes released from the flux and the cadmium fumes released from the silver solder rod. Most instructions say to use in a well ventilated area, whatever that may mean. Personally I silver solder small jobs in the workshop with the door open but try to do larger items outdoors, weather permitting! 
Circlip01/01/2010 18:49:56
1383 forum posts
Are we forgetting one part of the process not mentioned?? The bit that when the lumps have cooled to black heat and dunking them in an ACID pickle??
   In the days of PROPER acid (Sulphuric) pickles, you could watch the rust forming so it was advisable to "Do it" in the fresh air. Less of a fire hazard outside too.
  Regards  Ian.
Nigel McBurney 101/01/2010 20:17:22
945 forum posts
3 photos
HI a long time ago I started on an Allchin boiler and bought a propane torch kit,first time I tried it out in my workshop on annealing some copper,I did it on some firebrick on the concrete floor,it was all going well and getting nicely red hot until I got up off my knees and looked at my tools and the brand knew Myford,in that relatively short time there was a yellow rust film on most of the bright steel and cast iron surfaces,the rise in air temperature and the moisture frome the burning propane had caused instant corrosion.As I was annealing it was only the propane that caused the rust,I have never  heated work or silver soldered in my good workshop since.  I have an outer workshop for rough work  with double doors and a mobile steel bench and position it behind one of the doors so that the work is in shadow so that I can see if it is hot enough and keep the other door open for ventilation.Electric welding is always done outside ,the fumes can then be carried away by the wind.If I silver solder a large job like a boiler I would do it in the open air to avoid the fumes .
Martin W02/01/2010 00:41:22
905 forum posts
30 photos
Re rusting when using a propane burner etc. As Les said above burning hydrocarbons produces not only water but carbon dioxide. Here the real problem is the carbon dioxide in combination with the humidity. Being slightly acidic in solution it changes the chemical reaction, Fe(II) changes to Fe(III), and instead of forming a passivating oxide layer which adheres to the metal it produces an oxide which allows further oxides to form until the active agents, water & CO2, are used up.
So there is some wisdom in not using burners in workshops with bright metal but that said a thin coat of oil/grease will stop it in the first place. As my machines are in an unheated garden shed I tend to wipe them down with quite literally an oily rag at the end of the day. While it may hamper cleaning occasionally all the surfaces are as rust/tarnish free as when there were delivered. Again prevention is better than cure.
Cheers and a Happy & Prosperous New Year to All

Edited By Martin W on 02/01/2010 00:42:00

Tony Martyr02/01/2010 11:54:36
209 forum posts
41 photos
I have never suffered from rusting in my unheated garage/workshop until I started making my boiler and dunked hot metal into a sulphuric acid pickle - then I had a thin rust form selectively on my lathe chuck and milling table where there was no oil film.
Undoubtedly the cause was the acid fumes condensing on cold, unprotected metal.
I had been using the propane torch previously to anneal the copper without any rusting.
I now silver solder with the large door open and the pickle bucket has been removed to the garden in the hope it will reduce the pH of the soil and not rust my workshop equipment.
Martin W02/01/2010 14:07:12
905 forum posts
30 photos
Sulphuric acid vapour does exactly the same as CO2 in solution but is much more aggressive. It really depends on the concentrations as to how quickly iron/steel is attacked and also if there is any protecting coat on the exposed surfaces. I agree with you that pickling etc should be done well away from any machinery and the best solution, no pun intended, is to do it in the open air.
Martin W
mgj02/01/2010 15:51:45
1017 forum posts
14 photos
Well in the open is a bit dramatic in this weather?
I have moved all the soldering and SS out into another sort of shack outside the main workshop - and all the linishing and grinding kit has followed it.
I reckon that Bakers fluid fumes are worse than pickle for rust, but I may be wrong.!!!!!
Ian S C02/01/2010 23:07:01
7468 forum posts
230 photos
Some times when burning LPG,and othe hydrocarbons carbon-monoxidecan be produced,at least I think thats the case.Two trampers died not far from here 2yrs ago,it was found that they had thier camp stove lit in the closed tent to keep warm.If you use the torch inside VENTILATION is the thing most needed-it also helps with the condensation.Even an extractor fan wouldn't go amiss.Ian S C Until the suppliers got the mixture right you couldn't use the gas in the workshop in the winter,I used to go to do a job,turn on the gas and if I was lucky a tiny flame would appear-turn off gas,go inside and do something else.But now I can use the gas all year round.Its dearer now,can't use the gas so much!!!

Edited By Ian S C on 02/01/2010 23:14:12

Norman Barber05/01/2010 12:49:47
14 forum posts
I only carry out relatively small silver soldering jobs in the workshop and have never experienced rust problems on any of my machines, although I have now fitted a fairly powerful extractor fan over the brazing hearth.  Large jobs like boiler making are best done in the open air.  I am alarmed at the idea of putting a hot job (of any size) into a sulphuric acid pickle bath.  This can be very dangerous.  I always allow the job to cool down completely to room (workshop!) temperature before putting it in the bath.  It is true that cleaning takes a little longer from cold, but not that long.  My pickle tank is in the workshop and I have ever had a problem from acid fumes.  I have, however, had problems when soft soldering using Bakers fluid.  I agree with Meyrick.
Norman Barber
calder percival 104/03/2010 20:06:51
19 forum posts
1 photos
cadmium free solder is now available readily and soldering in ventilated areas is so much more fun than breathing dangerous chemicals.
Ian S C05/03/2010 02:08:55
7468 forum posts
230 photos
Sulphuric acid on its own won't cause rusting. With reference to vol one of ME, an artical on rust prevention. Conentrated sulphuric acid is placed in a small glass dish, and for example place in a cabinet with the exhibit on display that may be liable to rust.The acid will not evaporate, but will absorb atmopheric water(leave room in the glass container),when diluted, put in the pickel bath. I would'nt really recomend the idea, it could end up a bit worse than a bit of rust. Ian S C
Speedy Builder505/03/2010 12:48:13
2447 forum posts
195 photos
As Mr Percival, it could be the cadmium effect.  I have had problems with all my electricity cable clips softening and the cables then drooped like spagetti.  Now I have another problem.  I installed a suspended automatic fire extinguisher as the workshop is an insulated wooden structure,  now I am scared that I might set it off by accident,  either by the heat of the brazing hearth,  or by accident clouting it with a piece of wood stored in the 'loft'.

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