Okay, a little o/t for an electronics forum but I couldn't find anywhere better to ask. Hopefully soldering questions belong here?

So yesterday I found a little tin of "Burnley Soldering Paste" from around WWII. I collect old bottles and tins, so I'd like to get this one all nicely cleaned out for display. Of course, it's still half-filled with this immensely sticky, slimy, indelible shit-brown gunk. I scraped the bulk out and used a hard wire brush to get the paste off the outside lip of the tin and the inside of the lid, but this completely gummed up the brush and there's still a thin layer inside the tin that won't come out with any amount of scrubbing, brushing or detergent. Anyone have any suggestions on how to chemically abolish ALL of the soldering paste from its tin without, ya know, completely corroding the tin itself?

 

Easiest way to get most of it out is just warm it up and pour it out. I do that when my solder paste gets lots of bits of bench debris in it. Then wipe out with soft paper towels 'til it looks clean. I would then wipe yours out with a solvent like naptha (white gas, lighter fluid). Though, when it's clean as a whistle..it might rust. Depending on what you are using it for, you could coat the inside with something.

Ken

 

Okay, a little o/t for an electronics forum but I couldn't find anywhere better to ask. Hopefully soldering questions belong here?

So yesterday I found a little tin of "Burnley Soldering Paste" from around WWII. I collect old bottles and tins, so I'd like to get this one all nicely cleaned out for display. Of course, it's still half-filled with this immensely sticky, slimy, indelible shit-brown gunk. I scraped the bulk out and used a hard wire brush to get the paste off the outside lip of the tin and the inside of the lid, but this completely gummed up the brush and there's still a thin layer inside the tin that won't come out with any amount of scrubbing, brushing or detergent. Anyone have any suggestions on how to chemically abolish ALL of the soldering paste from its tin without, ya know, completely corroding the tin itself?

Ultrasonic cleaners have started turning up in retail outlets.

Maybe get some litmus to determine whether its acid or alkali - then use a detergent that's opposite, to neutralise it.

 

Okay, a little o/t for an electronics forum but I couldn't find anywhere better to ask. Hopefully soldering questions belong here?

So yesterday I found a little tin of "Burnley Soldering Paste" from around WWII. I collect old bottles and tins, so I'd like to get this one all nicely cleaned out for display. Of course, it's still half-filled with this immensely sticky, slimy, indelible shit-brown gunk. I scraped the bulk out and used a hard wire brush to get the paste off the outside lip of the tin and the inside of the lid, but this completely gummed up the brush and there's still a thin layer inside the tin that won't come out with any amount of scrubbing, brushing or detergent. Anyone have any suggestions on how to chemically abolish ALL of the soldering paste from its tin without, ya know, completely corroding the tin itself?

The old solder pastes use pine resin as the matrix. Some were plain pine resin, some had bits of other. Although the term "solder paste" is on the container, it is essentially a flux instead of the modern term of solder paste that refers to a metal power of tin alloys that can be heated to solder a part in place.

Unfortunately, pine resin turns into amber over many years - hard and impervious to many things.

You will have most luck by letting it resolvable into turpentine. Turpentine is the volatile If it is not too viscous. You could let it sit in the sun to warm it up (don't apply direct heat to solvents). Do this well away from your home as a solvent fire could be bad (will be bad).

Take your time. The solvent that works depends how much original solvent is left in the mixture. Some articles will tell you that isopropyl alcohol works, but, if too old and hard, Not so much as when fresh from the tree. Soap, water, acid and bases will mostly be a waste of time. Solvents will be your friend. Likely denatured ethanol or isopropanol if you can find it. Acetone or methanol are also worth trying.

 

Pine resin sounds about right. It's actually not hardened at all, just immensely sticky.

So the next step is to fill the tin with a solvent like naptha, acetone, or an alcohol and let it dissolve the remaining residue? I'll see what I have on hand and give it a go. Thanks!

 

Listen to everyone above... The cleaners might take the paint off and ruin the tin.. Use a heat gun or something similar to turn the paste into a liquid and it will pour right out and no fuss..

 

From a collectors' pov... the container is worth more if the original contents are intact... Be very careful not to louse up the exterior of the can in an effort to clean it...

 

From a collectors' pov... the container is worth more if the original contents are intact... Be very careful not to louse up the exterior of the can in an effort to clean it...

With most soldering fluxes - the original contents will eventually eat the tin.

 

Do not use acetone it will take the paint off, alcohol should work.