Everything on model trains, model railroads, model railways, locomotives, model train layouts, scenery, wiring, DCC and more. Enjoy the world's best hobby... model railroading!
How To Prevent Dull Solder
Erin D asks readers:
“I am new to soldering and wondered why my solder finish is kinda dull and even a bit grainy in appearance. Is that how it should be or am I doing something wrong?”
Send in your question to our volunteer Blog Moderator and have it published on this Blog. The link is directly below.
24 Responses to How To Prevent Dull Solder
Leave a Reply
SUBMIT YOUR QUESTION
Download Your Free Catalog
Use Tiny Railroad Micro Controllers
Model Train Help Ebook
To cold and maybe not clean enough
Sounds like you’re not getting the solder and rails hot enough. The solder should flow onto the rail and cool to a smooth, somewhat shiny finish.
Make sure the soldering iron is held against the rail until the solder flows onto the rail.
Solder is shiny when it is liquified, but usually it is pretty dull in appearance, like lead is when it solidifies. You want to make sure that the metal you are soldering is warm enough that the joint is good so the electrical conductivity will be good. There is nothing worse than a cold solder joint which looks nice, but doesn’t really make a good circuit. But, don’t be alarmed that it goes from shiny to dull.
Dull soldering joints usually mean a “cold” solder joint. To get even flow of solder the iron must be hot enough to not only melt the solder but to add heat to the item(s) you are soldering. It also could mean you’re not using the proper flux for the solder joint. You should NOT use plumbers solder with acid flux but use a solder with a rosin flux. I use solder that has rosin flux in it and also use a can of rosin flux to add even more flux than the solder itself can deliver. That and plenty of heat are all that is necessary for a good solid solder joint.
Go back and reheat all the joints with a hot iron. Hold the iron on the joint until the solder flows. Then pull away without moving anything. Use a pencil iron no greater than 30 Watts with a touch of flux and rosin core soldier, thinner I’d better. Put dab of solFer on the iron tip and carry it to your work. I’ve been a ham radio operator for 30 years and an air force airborne radio man before that. These steps work for me. Acid core solder will desolve the insulation. Don’t be scared. Every mistake can be corrected.
Rusty has it right. Use rodin vote solder. Make sure your iron is clean a d HOT. I also put flux on the joint. Flux on the the joint sill make the solder flow like water. Good luck, keep practicing
Be sure your using solder designed for electrical work and not lead based solder as used for plumbing and metal repairs like radiators, etc. . Secondly, I always use a bit of soldering flux which helps a lot. Third, be sure the soldering gun or iron is really hot.
Solder should be shiny after following these three steps. It should melt rapidly and flow smoothly onto
the joint. Once cooled and cured, it should be fine.
I wasn’t drunk when I wrote that….on screen keyboard…lol
Hi Ron,
I wished you hadn’t explained your computer glitch, and I know where your coming from I do it all the time. I was just looking forward to the next issue of this forum, and everybody asking where do I get this fabulous stuff from it sounds great.
I agree with the other comments. You don’t need solder joints that are as shiny as mirrors, but the end result should look smooth. Any kind of electrical flux (liquid or paste) will do. Also, using a bright boy or other gentle method to remove crud before soldering would be helpful.
Conventional soldering would include holding a fluxed and tinned wire against a fluxed and cleaned outer web of the rail with a sufficiently hot soldering iron and then adding a little more solder to the joint. When the solder flows, remove the heat. You may think you need one or two more hands, but it works. Good luck.
also keep a damp sponge handy. wipe the tip of your iron across the sponge before you solder each time. this will keep it clean and remove excess solder.
everyone has covered the technical side of soldering but also sounds as if you are suffering from melting the plastic ties on the track. You can avoid this by using heat sinks on both sides of your solder joint. You can make heat sinks by taking two pair of needle nose pliers and putting rubber bands on the handles to keep the pliers shut. place one plier on each side of your solder joint and they will soak up the excess heat and keep your ties from melting. Good luck with soldering and practice makes for improved joints…..
One o things not mentioned is:- Is the solder the correct type for your Iron and vise verser. Is the Ironof a correct wattage for the work you are doing? Good luck and enjoy the hobby.
*vice versa.
It appears everyone ha covered it all. The only thing I can add is put the iron on the top of the rail, this decreases the possibility of melting the ties
Cheers
Hi Erin,
Everyone has covered soldering very well, and some very good advise- very good, hot iron (not to big, general purpose), good solder, good flux ( not household solder ) heat sinks and lots of practice on scrap and old pieces of track, we all learn something new every day, all you have to do is ask it’s the way we learn I’m still learning through the above chaps who have made great and informative comments, and at 70+ years still loving it,and as Ken Patterson would say “Its the greatest hobby in the world “. A source for soldering and electrics especially DCC , go to dcc concepts.com a WA based company now operating in the UK .
Hi Erin, nearly all the bases have been covered, if you are new to the art of soldering, I take it you have a new iron, did you set up the tip from new, i.e., before turning it on take a length of solder and wrap it around the tip tightly, then switch it on, this will Tin the tip which allows for a better soldering process, also get used to wiping the tip on a damp( not wet) sponge pad after every joint, this keeps all the crust away, Correct solder and flux are a must as with the right wattage iron, the process with practise becomes very easy,
Stew
I must add. The soldering iron tip Must Be Clean and shiny. I keep a copper/can be steel/scrub brush handy. (Bought 3/$1 at Dollar Tree). And use it to scrub the iron tip each time I use it. i.e. Heat the iron, tin the tip. tin the item being soldered/rail and wire. Do this before touching the iron to the rail. After you have a bit of solder on the rail and wire, then put them together and hold still while applying the iron. Just a quick touch is usually enough. Yes, you must have the rail and wire hot, but you don’t need to hold the iron on them for very long. I think the scrub brush is better than a wet sponge. Use flux sparingly, not a lot/Just enough to help the solder melt.
Erin:
The issue is two fold. One: The soldering Iron is not large enough to maintain the heat needed to properly melt the solder. Two: Because of the mass of the rail, the heat is is being distributed along the whole length of the rail. If you use a larger Soldering Iron you would begin to melt the Ties. I have been soldering my power connections to the Track Clips. This Hides the wires and eliminates the issue of melting the Ties.
My Process:
Step 1: Using a pair of needle nose pliers or forceps, I clamp the track clip so that 80% of the bottom is exposed. I use a pair of vice grips to hold my “clip holder” so that the bottom of the clip is facing up.
Step 2: Using a piece of sand paper or a file, polish the bottom half of the clip to make it clean to help the solder stick.
Step 3: Heat the clip with the soldering iron while feeding some solder onto the clip. Suset enough to coat the area you want to connect the wire to.
Step 4: Strip the coating off of 1/8 inch of the wire you are connecting to the clip. Then using the Soldering Iron, heat the wire and tin it by adding solder. If the wire is stranded, it will soak up the solder.
Step 5: Now solder the wire to the bottom of the clip by heating both the clip and the wire at the same time. After the solder melts, remove the iron and let it cool before removing it from the clamp.
Good Luck!
THAT SOUNDS LIKE A GREAT IDEA TKS FOR THAT I DON’T NEED IT YET .
A few points about multi-flux and, indeed, plumbing solder: Firstly; Most solder sold today is lead-free and in both electrical and plumbing applications the finish is slightly dull. Those people getting beautiful shiny finishes are probably using the old type of solder that they’ve had for years and years. You can still buy solder containing lead at major electronic component suppliers but you must stipulate you want lead-based solder or play it safe and settle for lead-free and accept that you’re never going to get shiny joints. Secondly; Solder will flow from the cooler area to the hotter so always place the iron on one side away from the joint and apply the solder to the other allowing the liquid solder to run around the joint on it’s way to the iron. Thirdly; It’s all a matter of timing, apply the tinned iron to the joint. When the joint is hot (you can judge when it’s hot enough by tapping the solder gently on the joint and a small wisp of smoke will be emitted) apply the solder, when the solder has flowed around the joint remove the solder and THEN the iron. If you move the iron first you’ll get what is called a whisker as the end of the solder is pulled away from the cooling joint. DO NOT move the joint before the solder has set.
Cleanliness is paramount. The flux performs three jobs 1) it melts before the solder and being slightly acidic and cleans the joint 2) It forms a shield over the joint to stop it oxidizing before the solder does it’s job 3) It helps the heat to flow from the iron to the joint. So if you’ve burned the flux off before the joint is complete these advantages are lost and you will fail to make a good joint. some-times you can get away with adding additional liquid flux.
Thanks for that – I’ve been trying for years to get good solder joints, but never heard anyone suggesting a couple of your suggestion. I’ll try them out next time I do some soldering
Nobody mentioned using a track gauge while soldering. This will help keep track in alignment even if the plastic ties soften a little while soldering which in turn allows longer application of heat. Once the heat is taken away, the plastic hardens again. The one I use also serves as a heat sink as well. My hands are very shaky but I still get clean soldered joints on my N scale layout.
All god points above. One thing to remember is to not let the parts move until the solder hardens. You need an iron that can deliver enough heat very quickly to the point of the soldering. If not, you will melt the plastic while waiting for the heat to build up to melt the solder. The idea is to keep the iron as short as possible a time in contact with the rails. Once the iron is withdrawn, make sure nothing moves before the solder hardens.