Stop Silver Solder Running

I've always used a soft lead pencil line to stop silver solder running. Damned hard to get a good clean line sometimes, particularly on brass, so I tried a few other ideas.
Found that typing correction fluid works perfectly. I buy the small bottle with the brush - gives a clean accurate line, quick to apply, & no clean up.

Disclaimer - of course its probably toxic like most of life these days, but I'm still here. Apologies if its a 'known' but I havent seen it mentioned before.

Gippy

the new water base non toxic stuff is not as good as the old trik. based stuff good job i have a stock of the old stuff

its a H&S issues the typists were sniffing it and making more missaks and using ( sniffing ) it more 


Stuart

thank you for the tip, I will try that

Correction fluids used 1:1:1 trichloroethane, Various trade names such as Genklene (UK), Dow Horgen Swiss. We used to make a fair tonnage every day until the Montreal Protocol came along. Trike is trichloroethylene (Triklone) still used industrially but evaporation rate is too slow for correction fluids. Typists, as opposed to computer operators, were relatively busy and expected to churn the work out.
All these chlorinated solvents including Arklone used in dry cleaning, give off vapours that are heavier than air and collect at ground level, in tanks and basements, in the process displacing the air and leaving none to breathe. These substances are/were non-flammable, a great advantage.

Accidents were frequent but the manufacturers largely stopped producing 1:1:1 trichloroethane because of the destruction of the ozone layer with such a volatile substance being often used under uncontrolled conditions.

Jerry

Trichloroethylene is not something you want anywhere near freshly machined aluminium 

There was a company in the south of England that many years ago where someone dunked a hot bit of freshly machined aluminium into the trike tank to clean it off and forgot to take it out on a Friday evening. Monday morning the inevitable had happened the hydrogen chloride and hexachlorobutene vapour had coated the entire machine shop. It was all a write off 

Jo

I use type of engineers chalk (thin stick) from Brownells I got years ago and never had a problem and easy to clean off. used when soldering (not soddering ) sights etc.
Pete

Jo,
You have the circumstances and results correct but it was actually 1,1,1 trichloroethane  (CAS 71-55-6), (Genklene?) in the tank. The solvent was stabilised (composition was a trade secret) but the stabiliser vapour was more volatile and lighter than air so it tended to evaporate, leaving the 1,1,1-tri in the tank unstabilised. The cooling coils which prevented loss from the vapour degreasing tank had been turned off, and the inevitable result of all this was as you say.
At this distance in time I am not certain of the evolution of hexachlorobutene.
I have a copy of the tech service report somewhere but as it was an internal document it cannot be published.

Vapour degreasing tanks generally contain >100litres of solvent; correction fluid ~20 ml.

Jerry

Jerry I don't remember the exact details it was over 20+ years ago. But the lid was left open and I suspect the power turned off to the workshop 

I do recall when I worked for a company that made torpedoes we had our trike tank, which was used for degreasing the sections prior to assembly, in a separate building to everything else. They were really, really careful with it and access was very restricted!

I think it was Trike that we used for cleaning up the circuit boards as we assembled them. Great stuff, nothing afterwards did it as well I recall them getting worried about us inhaling the fumes, maybe they thought we might be enjoying ourselves too much  .

Jo

Many, many years ago there was a case of an RAF technician who went back to work after everyone had quit for the day to clean some private motor parts in a work Trich bath.  Unfortunately he was overcome by the fumes, slumped head first over the bath and wasn't discovered till the following morning by which time he was severely brain damaged.  Trich was very hard to get in the RAF after that.  Perhaps it's no bad thing that it's still tricky to get.
I also seem to recall that Trich was used in fire extinguishers at one time but I may be wrong about that one.
Jim

That was CTC

Carbon Tetra Chloride  excuse the spelling also used in dry cleaning and a product called Dab it Off

Stuart

CTC!  That's the stuff.  Good job I wasn't a fireman innit? 
Jim

Jo,

You've certainly got a good memory. I only recalled the detail after you had mentioned the occurrence.
It was in 1982-3 I think or perhaps earlier as I changed jobs in '84 and never got involved with chlorinates solvent formulation afterwards.

Best regards
Jerry

I worked many years ago in a company that manufactured valves for nuclear reactors. Before the individual components were assembled, they were cleaned in a trichloroethylene bath and then touched only with white cotton gloves.
The stuff was also good for cooling when working on stainless steel.
There was always a container with the mixture next to the drilling machine.
The painter in the company used it to clean his tools and wash the surfaces before painting.
In the mid-1970s, no one cared about environmental protection.
The wastewater from the electroplating and chemical baths was discharged into the nearest stream without any after-treatment.

Back to the original topic of this post ...... 
(Typos fixed)

The Silver Solder will only flow where there is flux on the surface.  As an RAAF Fitter, often silver soldering very small instrument components, we were taught that the flux should be applied very sparingly, and only in the places that you want the silver solder to flow.  When you heat the job, the flux liquifies, and capillary action will carry the flux through the joint - and capillary action will allow the silver solder to also flow into the joint.  If you've got excess flux on the job, the flux that does not flow into the joint, will flow down hill on the job creating the messy silver soldering result being referred to by the original poster.    Silver Solder Fluxes can usually be "diluted" to make them easier to apply in small quantities, and exactly where you want it.  My understanding is that most modern silver solder fluxes are water based, and so a small amount of the flux paste can be mixed with water to make a more runny slurry - at least on the brand of flux that I use.

But also - thanks for reminding me of all of those nasty chemicals that the Air Force had people like myself using, with no PPE and no warnings....

Correction fluid works . Be careful that it is dry before applying heat. I was in a hurry one day and began the heat right away. The part caught fire, had to blow out the flames and clean up the mess i made. It dries fast so probably 1 minute or so will be enough time before applying the torch.