RMweb Gold 57xx Posted January 1, 2020 RMweb Gold Share Posted January 1, 2020 I have a new toy to play with after Christmas and so dug out my small tub of solder paste only to find it has gone rather stodgy. Does anyone know what solvent is used in it to thin it down? Link to post Share on other sites More sharing options...
Andy Reichert Posted January 1, 2020 Share Posted January 1, 2020 Usually Flux. Match the flux to that already in the paste. Also warming the paste should make it more inclined to flow. place the (sealed) container in some hot water. Do NOT put any paste in the microwave to warm it.. Andy 1 1 Link to post Share on other sites More sharing options...
michl080 Posted January 2, 2020 Share Posted January 2, 2020 (edited) Ric, I have solder paste that is normally used in the electronic industry. If I am using the paste as it comes, it spatters quite heavily. So I mix the paste with Flux (phosphic acid 25%) to a soft creamy texture. This improves the wetting of the brass and reduces the spattering. I should add that Andy's comment about using the same flux is correct. I am using my method with small amounts of solder paste. I think that the solder will corrode after some time if is is exposed to phosphoric acid. Michael Edited January 2, 2020 by michl080 1 Link to post Share on other sites More sharing options...
RMweb Gold 57xx Posted January 2, 2020 Author RMweb Gold Share Posted January 2, 2020 (edited) Thanks both for your replies. I have no idea what the flux in the paste would be, it's a pot of "mechanic" solder paste from Hong Kong, my Cantonese is non-existent, assuming it's even mentioned on there! The only discernible bit is that is a Sn63/Pb37 mix. I have a pot of Carrs Yellow that I was going to do a small test of thinning with. Perhaps the best course would be just to mix small batches with the phosphoric acid as and when required. Edited January 2, 2020 by 57xx Link to post Share on other sites More sharing options...
RMweb Gold Phil Bullock Posted January 2, 2020 RMweb Gold Share Posted January 2, 2020 Surely all that will have evaporated is the solvent - probably water! Try adding a drop to a small amount and see how it works.... Link to post Share on other sites More sharing options...
RMweb Gold 57xx Posted January 2, 2020 Author RMweb Gold Share Posted January 2, 2020 1 minute ago, Phil Bullock said: Surely all that will have evaporated is the solvent - probably water! Try adding a drop to a small amount and see how it works.... That was my thinking Phil. My kitchen cupboard looks like a solvent shop with many different options I could play with, but thought I'd ask first before multiple experiments. Link to post Share on other sites More sharing options...
RMweb Gold Phil Bullock Posted January 2, 2020 RMweb Gold Share Posted January 2, 2020 I have some Carrs solder paint which I keep leaving the top off so will probably need to do the same.... Link to post Share on other sites More sharing options...
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