| Electronics > Repair |
| Restoring dried solder flux paste |
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| tooki:
I tried various ratios, stirring while cooling vs. leaving it still, nothing made any difference. Nothing at all like the old Kester 44 rosin flux paste I have a tin of, which is clearly a true dissolved mixture, since it can be remelted without any kind of separation, so it's not a suspension or emulsion. From the (many, many) flux MSDSs I looked at, and a few other sources, it's pretty clear that for liquid fluxes, unprocessed rosin can be dissolved in solvent, but that for petroleum jelly based paste fluxes, the rosin is processed first. |
| SilverSolder:
Are all paste fluxes based on petroleum jelly, or only some of them? |
| jpanhalt:
@tooki I just bought a pound of gum rosin. That's about 8X the amount of paste flux I have used in 50 years. Should last me awhile. :) My hypothesis is that your mixture is all wrong. I suspect something like 1% to 5% petroleum jelly is what is needed, maybe even less. Should arrive later this week, but an unusually strong Winter storm is brewing, and shipping may be delayed (i'm in a very remote area). Will test and report. John |
| tooki:
--- Quote from: SilverSolder on February 15, 2021, 09:57:14 pm --- Are all paste fluxes based on petroleum jelly, or only some of them? --- End quote --- No, not all are. Newer flux formulations tend to use other things. --- Quote from: jpanhalt on February 15, 2021, 10:00:22 pm ---@tooki I just bought a pound of gum rosin. That's about 8X the amount of paste flux I have used in 50 years. Should last me awhile. :) --- End quote --- I should think so! :D --- Quote from: jpanhalt on February 15, 2021, 10:00:22 pm ---My hypothesis is that your mixture is all wrong. I suspect something like 1% to 5% petroleum jelly is what is needed, maybe even less. --- End quote --- Not a chance. A 99% rosin concoction, provided you found a way to make a stable mixture, would be a solid, not a paste. Kester SP-44 was 25-50% rosin according to the MSDS. (The MSDS doesn't list petroleum jelly, but other sources say that's what its base was.) MG Chemicals 8342 rosin flux paste's MSDS says it's just 5% rosin, 10% paraffin oils (which could overlap with petroleum jelly, that being such a loosely defined term), a few % acids, with the balance unspecified. SRA #135 rosin flux paste's MSDS says it's 30-50% rosin, 20-40% petroleum jelly, and the balance "non-hazardous stabilizers, and water". (That paste has the most similar appearance to the Kester SP-44 of all the still-available rosin paste fluxes I've seen.) --- Quote from: jpanhalt on February 15, 2021, 10:00:22 pm ---Should arrive later this week, but an unusually strong Winter storm is brewing, and shipping may be delayed (i'm in a very remote area). Will test and report. --- End quote --- Please do!!! If you do find a way to make a functional rosin flux paste, I think many people would be curious. (I've seen a few youtube videos claiming to do so, but I am quite certain they're fake, in that they claim to add a small amount of IPA to solid gum rosin to make a paste, but then when they demo the paste, it's a very pale yellow paste, not the dark amber the rosin would be.) |
| jpanhalt:
One experiment is worth 1000 expert opinions or TDS's. Why do you think ChipQuik's TDS's are so vague? (PS: ChipQuik's use of bismuth in its low-melting solder is a matter of marketing.) Will report back as weather and the USPS allows. |
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