02-05-2017 Post does not mapped to Knowledge Tree Paul S San Diego, California, USA Posts 2,797 Joined on 10-12-2006 Post #: 21 Post ID: 22950 Reply to: 22948 Neutrality Yes, try ethanol (with as little water in it as possible). Contact cleaner is typicalyl just that.  I have ass-u-me(d) that part of your post-solder cleaning involves something alkaline, as well, to neutralize the solder flux. That's why I also water wipe (then dry) to finish, to get the alkaline residue off.  I tend get more build-up on the joints than others because I flux the hell out of thick parts, especially, and this absolutely requires scaling as part of cleaning the joint. Paul S

02-05-2017 Post does not mapped to Knowledge Tree Paul S San Diego, California, USA Posts 2,797 Joined on 10-12-2006 Post #: 22 Post ID: 22951 Reply to: 22950 One Example (of MANY!) Here's one example of what I mean regarding cleaning a solder joint: https://gokimco.com/chemtronics-es835b-flux-off-rosin-flux-remover.html?gdffi=a2b2595eeb2e44a8bc2e332d298712bc&gdfms=D2663A01824B473FAC1E75660BF93E39&gclid=CLWNztik-tECFUlNfgodZUgKGg Plenty of options, all "base" in nature. Best regards, Paul S

02-06-2017 Post does not mapped to Knowledge Tree N-set Warsaw, Poland Posts 642 Joined on 01-07-2006 Post #: 23 Post ID: 22952 Reply to: 22951 Flux remover Paul, I'm using this one: http://uk.farnell.com/kontakt-chemie/kontakt-pcc/flux-remover-aerosel-200ml/dp/2532504 Cheers, Jarek

02-06-2017 Post does not mapped to Knowledge Tree Paul S San Diego, California, USA Posts 2,797 Joined on 10-12-2006 Post #: 24 Post ID: 22955 Reply to: 22952 Only Because of the Bubbles... No doubt there are any number of ways to get a nice coating of natural shellac over clean, chemically neutral, soldered connections, but you did mention you have "bubbles", and there must be "chemical" reasons for this.  I looked up the cleaner you are using, and there is no indication that it is alkaline, which a specialized flux remover should be, as far as I know. One first needs to remove the residual rosin (including scraping, as necessary), then one needs to neutralize the residual acids (from the flux).  Then one can clean it in a way that leaves it "neutral". Then the traditional shellac (with denatured alcohol) can be applied in thin layers. Here's a spec sheet I found on your cleaner.  You can check your cleaner with litmus strips, of course.  However you manage it, you are aiming at a clean and chemically "neutral" joint under the shellac, and no "bubbles". http://docs-asia.electrocomponents.com/webdocs/136b/0900766b8136b1bf.pdf Best regards, Paul S

02-06-2017 Post does not mapped to Knowledge Tree N-set Warsaw, Poland Posts 642 Joined on 01-07-2006 Post #: 25 Post ID: 22956 Reply to: 22955 PCC data Paul, thank you for your explanations. No idea if PCC is alkaline but according to its manufacturer it has some isoalkanes and isopropyl. Visually it does remove it quickly (also my Cardas solder is not leaving much of a flux): http://www.kontaktchemie.com/KOC/KOCproductdetail.csp?product=KONTAKT%20PCC I'll ass-u-me that the bubbles are due to the slowly evaporating isopropyl in too thick applications of the coating and I'll leave the phonocorrector with the bubbles. I have no intention to go cleaning all the joints. Will try the denaturated alco solution with next solderings. Thanks again, Jarek Cheers, Jarek

02-06-2017 Post does not mapped to Knowledge Tree Paul S San Diego, California, USA Posts 2,797 Joined on 10-12-2006 Post #: 26 Post ID: 22957 Reply to: 22956 Flux Is Acid You need acid (flux) to flash clean the metals as they are being soldered and prevent a "cold joint"/poor bond that not only spoils transmission initially but it oxidizes and worsens faster over time. If you've used enough flux for a good joint (especially with thicker/heavier gauge materials), then you will have acid and also acidic oxides on the metals after soldering. No matter visually "clean", the metals need to be chemically neutralized to stop oxidation and/or electrolysis happening under the shellac, which only works, after all, to keep oxygen from a "perfect" soldered joint. No sense putting shellac over a corrupted joint Paul S

02-06-2017 Post does not mapped to Knowledge Tree rowuk Germany Posts 461 Joined on 07-05-2012 Post #: 27 Post ID: 22958 Reply to: 22957 Vintage connections better Remember wirewrap with the sharp cornered posts? The amplifiers that I built that way are still noise free after 40 years. 20 turns or so per post work just fine and those connections can be shellacked. Whenever I feel blue, I start breathing again.