What REALLY makes a smooth solder seam?

You all know that lumpy solder seam feeling. You try and TRY to improve your stained glass soldering techniques but STILLΒ you can’t get a nice smooth finish.
Well I have a secret for you.
It’s a tiny but crucial tip – taken from my Stained Glass Made Perfect CourseΒ – that will improve your stained glass soldering techniques and help you get over the hump and start producing smooth, even seams to be proud of.
Youβll see that it isnβt a question of speed, or the right flux or the correct solder – although these things help.
Itβs all about controlling the heat of the solderΒ with the angle of the soldering iron tip.
Stained Glass Soldering Techniques
Have a look at the Video Tip belowΒ and give it a go yourself. Play around with the angle of the tip. Try it flat, try the corner, try the side. This will help you:
- see how the solder behaves differently.
- learn how much heat is transferred to the solder with the different angles.
- start to control of your soldering iron.
And with that control comes smooth, even solder seams.
You might not have instant success but if you keep at it I can guarantee that your stained glass soldering techniques will improve.
P.S. If you got value from this free sample class, please Pin on Pinterest or Share on Facebook with your friends and fellow glassers who want to make stained glass to be proud of. Thanks.
More Stained Glass Soldering Techniques
- Try looking just ahead of the iron’s tip, not directly at the tip, as you move the iron along the seam.
It’s like driving. The more road you can see ahead, the more anticipating you can do and the better you drive. It’s the same with feeding solder to the tip. - Don’t be afraid to move your panel so that you get the best angle for running the bead. If you’re in the wrong position it will make soldering smoothly more difficult.
- This might challenge you but try holding the iron like a pencil and drawing it towards yourself. Rest your soldering hand on the bench to stop it wobbling as you go. You might find that this gives you better control. As always; find what suits YOU, not anyone else.
- Try dropping a series of blobs along the seam and joining them up to make the smooth seam.
That way you don’t have to worry about feeding the solder. This is the technique students find most helpful in the Stained Glass Made Perfect course. - Try flat soldering the front side first, making sure that the gaps are filled. Wipe of flux, turn over and bead Side 2. This is now easier as there’s no gaps for the solder to get sucked into. See image below.
Go back to Side 1 and run the bead. This is now easier as there’s a solid base that makes running a smooth seam easier.
By beading Side 2 first you get a soldering warm up and can identify problem areas to pay attention to when you go back to Side 1.
If you get the hang of this you may find in time that you don’t need to tin first.

Solder Smooth Intersections
- When you hit an intersection, solder down each ‘spur’ about half an inch before returning to the main line. See image above. The solder will remain liquid.
When you’ve finished the main line you can go back to each ‘spurs’ and easily pick up where you left off.
This will avoid solder collecting at and forming lumpy intersections.
Tool Related Soldering Tips For Smooth Seams
- Experiment with temperature to suit YOU. Find the temperature that works for you. This will change depending on what you’re doing too. Edges, internal seams, decorative soldering. They all need slight adjustments in temperature and speed.
- Too much flux can cause problems. Flux will splutter and can get trapped in the gap between glass and spit when you solder side 2.
- Make sure you keep the iron tip clean by wiping it frequently on a damp sponge to remove the build up of residue.
- Check that your iron is maintaining a constant temperature. Weller soldering irons have the reputation of cool spots and it’s another thing to factor in. The Hakko FX 601 maintains a very even temperature which helps.

Learning To Relax
- Don’t worry about doing the seam in one pass. It creates too much pressure. Try making a run of solder over the seam without worrying about smoothness. Then go back and make the bead on the second run. As long as you let the solder cool down in between you can go over it a few times.
Let go of expectations, it’s liberating! - Learn to slow down, you’ll make smoother lines if you do. Because glass expands at the edges when heated it’s very VERY unlikely that you’ll crack the glass. Soldering overlay in the middle of a shape is much more likely to crack the glass so you have to speed up a bit with that.
If you have any other tips, feel free to add them in the comments below. You may help others achieve smooth solder seams. My students often find good ways of explaining things to help the penny drop!
Have unsightly gaps? Go here to see a video on how to fill and solder them
Toss out your sponge, start with a new, clean,(no soap), sponge. Always use distilled water for wetting the sponge. It will last longer and more importantly, the irons tip will last longer also.
Ps, love your site, Milly!
Thanks for your additional tips Mark. And for loving my site π
Hi Milly and thanks for soldering tips!
I want to add 2 tips that have been game changing for me.
1. As you come to the end of a solder bead go back over about halfway down the bead and the remove your iron straight off. No more lumps or pools of solder at your joins!
2. I use blue painters tape on one side of my piece before soldering especially if I have gaps. That way the solder doesn’t leak out the other side.
Have a wonderful day and thanks so very much!
Another two great tips Jennifer, thanks so much. I’ll definitely have a wonderful day now π
Thank you so much
What helped me the MOST was finally getting a quality soldering iron
I agree Elizabeth; cutters and soldering irons are the two pieces of your stained glass kit you shouldn’t skimp on. I wonder which one you chose?
When going over a bead again to re-work it, do you also need to flux the solder that we laid down first? I hope that makes sense!
Yes, if the flux has evaporated. You might want to wipe it of gunk too – to give yourself the best chance of a smooth bead.
Thanks Millie,
I find that using Canfield 50/50 solder gives a smooth bead pretty much effortlessly. Its the only solder that I use.
I love that solder too, thanks for the recommend π
How do you keep foil tape from wrinkling when tinning.
It sounds as if either your iron is too hot or you’re taking too long in the same place. Tinning a very quick swipe over and doesn’t give the foil a chance to wrinkle. Try turning your iron down or going faster and see if that helps.
When I made stained glass pieces I found the best way to get the solder smooth was to take deep breaths and gently run it over the lead.
Keeping calm and steady is the way to go Katharine π I’m assuming that’s what you meant; I haven’t heard of breathing on solder to get it smooth but I’m always willing to learn if you swear by it!
I also clean the soldering iron wiping sponge before each use. It seems to collect gunk and will show up in your solder.
Important addition Kimberly, thanks π
After spending four years away from my glass studio, I had many things to relearn. The major challenge was soldering and it was like everything in life…I had to slow down, I was frustrated that the macular degeneration changed my depth perception, but I began adapting, one solder line at a time.
My biggest discovery and “ah ha” moment came to me when I was working on joining panels of outdoor spinners. I just couldn’t seem to get my iron too in the 3d seam line but discovered a technique quite by accident. I found if I melted off a strip of solder the same length of the corner from top to bottom, and lay the cool solder piece into the fold, I could take my iron and melt the solder piece slowly from top to bottom and it worked marvellously! I proved to myself that being legally blind in one eye would NOT stop me from learning tricks to do what I once did so easily before my eye disease.
Thanks for taking the time to add that trick Diane. I can see it would work if you had the right width foil and solder. I say that because we in Europe are sold thick solder sticks and it would be far too much solder for a seam. By the same token, if you had narrow foil it might be too much solder. But a great idea if it ticks the points I’ve made π
I’m glad you’re back in the stained glass fold.
Some of my soldering lines are clumpy and too thick. It may be because itβs a combo of old solder and new solder of different kinds. But Iβd like to just remove it and try again. Can it be removed? Is the soldering iron supposed to lose its temperature while you are using it?
You can flux and melt off excess solder using gravity and scraping and ‘flicking’ the solder off the seams – carefully and wear safety gloves and goggles. Alternatively you could reheat them and try again, making sure you don’t overdo one area.
Honestly? I’d move on to a new piece and be philosophical about your learning process; it takes time to improve, bit by bit. It’s discouraging to keep going over the same thing and I’d hate you to lose your sense of excitement.
Hello Millie,
I have found a way to cut down on all those strips and drips of solder that are left after cutting pieces.
Rather than “cut” the solder piece by piece and sometimes hold it too long because it’s too short and too hot, I unroll the solder from the spool but don’t actually melt through it to give me a length. By unrolling the spool the solder is never too short in mid seam. When the project is done I just roll the slack back onto the spool. Voila…no leftovers, other than the usual drips. I collect those, put them in a cup and use them for spot soldering. It has reduced my solder budget immensely. A spool lasts much longer now.
That’s a great tips Debi, thanks for sharing. Just goes to show that doing small things can add up π
Thank you so much for this Millie! Soldering has always been my weak point. Your tips and tricks have helped me so much.
That’s great to know Pat, thanks for commenting.
Hello! My lines are okay but from time to time I need to fill a larger area with solder. I am working on a piece with a car and tried doing some of the grill in solder but it cools so quickly that I can’t get a nice finish. Any suggestions? It may be that the area is just too large to heat at once.
Hello π You can use either scrunched up bits of copper foil – make sure they’re flush or lower than the glass, you don’t want them to stick up. Or braided wire. I’ve got a video on filling gaps in stained glass with solder here. Hope that helps!
Hi Milly,
Thanks for sharing this. One thing I do when soldering is keep a wet cloth near by and clean the iron tip often. Getting a good iron is also important. Some fluxes break down sooner than others. Getting a good flux is equally important.
Great tips thanks Frank. What would you recommend for a flux, out of interest?
Does anyone have a suggestion to clean off solder that appears cloudy? I always clean the soldering and have tried to use steel wool to get it shiny , but not luck.
Have you tried Simichrome Polish after washing the flux off Nancy? Solder comes up a treat with that. Harley Davidson ‘people’ use it for the chrome on the bikes – and we know how they love their bikes!
The best way to clean solder before using the Simichrome is the Mr. Clean Magic Eraser! No water on it just the way it is. It’s awesome.
Thank you for sharing your tip Jennifer! It’ll be much appreciated by everyone reading this I’m sure π
Thanks Millie .
There can never be enough tips on getting that perfect solder line .
Some tips just ‘click’ and work for you, others don’t so much. It’s the nature of the beast! Good luck.