Lead Free Stained Glass Solder Problem
by Jan Sturgeon
I have a Weller 80 soldering iron. I have been working with it on several stained glass projects, with lead 60/40 solder and standard soldering flux and having no problems.
About a month ago, I switched to lead-free solder, and continued with various projects and all was well.
Last week though, I found the lead-free solder was no longer working with the soldering iron.
The soldering iron is having difficulty melting the stained glass solder, and when it does, it doesn't stick to the tip, but rather breaks apart in little balls. I read up on cleaning the tip, which I did by wiping with a sponge. That didn't do anything. I next tried scraping the tip with steel wool. That too did not work.
Yesterday, I bought a new tip for the 80W iron. I was told that since I was working with lead-free solder, I did not need to tin it. It was already coated with lead, and so, should work right out of the package.
So, I swapped it out with the one that wasn't working, and it worked great for about 1/2 hour. Then, the same thing started up, with the tip only working on it's edges. Deductive reasoning told me that maybe it was the flux I was using, or maybe it had something to do with the mix of lead-free solder and the lead-coated tip.
In any case, I'm at a loss as to what to do, and all my stained glass projects have come to a stand-still.
Your help would be greatly appreciated.
Milly’s answer: Great question Jan. This is a tricky one, weighing up the associated health risks of inhaling lead with the indisputed fact that soldering is more difficult – no, really annoying! – with lead-free solder.
The potential difficulties (some you’ve already experienced) are:
Poor solderability – the lack of lead decreases the ‘flowability’ of solder.
Higher melting point – lead-free solder melts about 20 to 45 degrees C higher than 60/40 solder. This results in a shorter life for your soldering iron tip.
Some ideas for optimising your chances of success:
Make sure you have the correct size tip for your iron (did you replace like with like in terms of size and shape?)
Your flux and tip cleaner should be labelled ‘lead free’
Buy flux that is able to withstand higher temperatures and longer dwell times – flux charring, or ‘black tip syndrome’ (sounds bad!!!) can result, meaning that the tip turns black and re-tinning becomes nearly impossible.
Clean and tin tip more frequently – keep your iron clean and fully coated (tinned) with solder, as oxidation can occur at higher temperatures.
And finally, I’m wondering if your 80W soldering iron is hot enough for lead-free solder? I’ve always used at least 100W for stained glass solder.
I hope that helps, and that you’ll soon be able to resume your stained glass art work – it’s awful when you can’t get on!
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