Been working through some tank problems and built a couple new ones. I was wondering what type of solder people are using 60/40 or StayBrite? I have always used the 60/40 but seems the StayBrite is considerably stronger than the 60/40. If you use StayBrite what soldering agent did you use acid/rosen? If acid how did you clean/neutralize it? I did one tank with StayBrite/acid and in 10 minutes it was rusting, lots of WD40 stabilized the outside but I didn't trust the inside so I tossed the tank. What do you use?
60/40 or 63/37 (eutectic) rosin core is fine. The very slight extra strength of Sta-Brite is not necessary - I have had plenty of tanks put together with 60/40 that inflated themselves in a crash from hydraulic shock, but the solder joints stayed together. As you found, never, under any circumstances, use the Sta-Brite flux - it can never be neutralized and will rust steel or iron for *years* afterwards. If you absolutely must, like on bare steel, use non-corroding plumbers flux paste.
The trick to soldering successfully is to use clean tinned material and apply sufficient heat. I use the K&S pre-tinned sheets - what most people would refer to as "tin" as in "tin can", which for all of anyone here's life, has been steel with tin plating. Don't use brass except in an emergency, particularly brass shim stock, which tends to split since it was hard-rolled.
When soldering, the solder has to be hot enough to *flow like water*, and it will have a slightly bluish tint. If it is clumping up, it's not hot enough. If it's beading up, it's hot enough and the metal is hot, perhaps so hot it oxidized. Both side of the joint have to be hot enough to melt the solder on their own., you cannot melt the solder on the iron and "carry it" to the joint and drop it on there.
If you are using 60/40, as the solder cools, there is a "plastic" stage where it gets thicker before it solidifies. If you move or disrupt the joint when it is in this state, it will harden with grain and be dull, and very weak. This can't happen with 63/37, it goes straight from liquid to solid, so in that sense it is a bit more forgiving. A properly-made solder joint will be very shiny with a slight "halo" of rosin around the edges. Clean off all rosin afterwards with lacquer thinner. Any dark "dots" of "rosin" remaining in the joint itself will eventually wash themselves out and cause a leak, every joint should be completely shiny silver from end to end.
DO NOT use a torch to solder tanks, unless you really know what you are doing and know how to go gently enough to not oxidize the metal or boil off the tin by overheating it.
Brett
Topic: Best solder for tanks? (Read 1358 times)