Flux Problem

What kind of flux do you use?

Although I press and flatten the copper foil against the glass carefully, it seems that flux still seeps under the foil. I have a problem with my pieces falling apart! I also have a problem washing the flux off the finished piece without loosening the foil. Please be specific about what flux I should be using.
Thank you! I appreciate this free help tremendously!


Your problem isn't the flux. Flux won't lift the foil. You need to make sure your glass is clean and free of grinder dust before you apply the foil. I wipe the edges of the glass with alcohol before I foil. After you get the foil on, use a fid or a foil roller to press it down on all three surfaces. Go over it a second time to make sure it's burnished tightly against the glass. If the foil isn't burnished well, flux will get under it (or water when you wash it) and cause the foil to lift.

One other thing to check, is to make sure the adhesive on your foil is good. If the foil is old the adhesive quite often looses it's sticking power.

So, it isn't the flux causing the foil to lift...it's improper application of the foil, or inferior adhesive backing that allows the flux and/or water to get under the foil.

Any flux meant for copper foil work will work. I like Glastar GlasFlux or Classic 100 Gel Flux.

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Liquid or Paste Flux

by David

What, if any, are the advantages of gel or paste flux over liquid flux? The paste flux I've found seems to be geared toward electronic applications. I work in copper foil and lead came and have been using the same liquid flux for came and foil since I started working with glass several years ago.

Would appreciate your thoughts.


I personally use a liquid flux for copper foil and a paste flux for lead came. The paste I use is Nokorode which is available in most hardware stores as well as from most stained glass suppliers.

I don't use paste on copper foil work. It's too hard to clean off the glass and it does splatter. You use a lot more on foil then on lead, thus a lot more splattering! The cleanup for foil is quite different from lead cleanup, and paste flux is difficult to remove with water. Glasflux is my flux of choice for copper foil.

I like paste flux for lead because it stays precisely where I want the solder to flow. It doesn't spread around like liquid flux does. I always get beautiful solder joints with it. It doesn't splatter on lead because you don't hold the iron on it as long as you do when soldering copper foil. For cleanup, I simply wipe it off before I start puttying. The putty and brushing with whiting process cleans off any paste flux that remains.

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Flux keeps getting black bits in

by Sue
(South Wales, United Kingdom)

Hi Sue

I am quite new to Stained Glass and am finding that the Solder 60/40 stick soler (UK) I am using keeps getting black bits in, I have changed supplier, I have changed tip on Soldering Iron, I have changed Flux PLEASE help I am now at the end of my tether, it is not only giving my soldering a lumpy finish but also I am wasting so much flux because it keeps contaminating it. I have spoken to 2 different suppliers about this problem and neither of them have any idea, the Soldering Iron (which nobody has heard of)I am using is the one I was recommended by my first Stained Glass teacher, it is a 200w, it does not have a temperature control on it, she said that we would find them so frustrating as they cool down at the wrong times??

Kind Regards

Another Sue from Sunny Wales, UK

A 200 watt iron is way too hot. No wonder you have black bits in your solder. If I were you, I'd invest in an 80 watt or 100 watt iron. You could try a temp controller, but I don't know if that would even get you 200 watt iron down to the correct temperature.

Your 200 watt iron must be big and heavy. I really think you'd be better off buying a new iron. If they are available in the UK, the Weller 100 watt iron for stained glass work (it has a light blue handle) would be the best one to get. You don't need a temp controller with it, as the tip controls the heat. You can buy different tips for different wattages. It comes with an 80 watt tip which will be good for most work that you'll be doing.

Keep your 200 watt iron...if you ever make lampshades, it will be just right for tinning vase caps!

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