100 degree solder

[David B]

I am having difficulty using this solder. It is my understanding that it will attach brass to white metal without having to tin the brass first.

Unfortunately, I cannot get it to bond with the brass, or at least have any strength of bond. I have cleaned the brass and used a small amount of phosphoric acid flux, but time after time, the solder just breaks away from the brass. It is beginning to look as though 100o has no particular advantages over 70o.

Does anyone have any observations or suggestions? There are places where I would prefer not to have to tin the brass first because it means extra work cleaning up, somethng I thought the 100o avoided, but I may have to resort to tinning and using 70o low melt.

[allanferguson]

I have been using this stuff since I first found it, in preference to the 70deg stuff, and have had no problems. I've even used it in "difficult" situations for brass to brass, such as soldering brass chimneys and domes. I use phosphoric acid flux (Carrs yellow label). I set my temperature controlled iron to 200 deg. One possible problem is that with largish lumps of brass it's possible to melt the solder without getting the brass to a high enough temperature for it to stick. The metal, of course, is carefully degreased as usual.

regards

Allan F

[David B]

Thank you, Allan. I am doing exactly the same as you are but I really am finding the stuff next to useless at the moment.

I have tried the iron a bit higher, at 225o but with no improvement. I have used it to attach axle boxes and springs to BB's W irons where it has held but not strongly. I have had several come off when inserting wheels. 70o is more work to use but makes a considerably stronger bond.

[jasp]

I was introduced to 100deg. solder by Steve Duckworth - he of scratch-built intricate valve gear and exquisite locomotives (see Snooze) and have, like Allan, found it to be excellent and so much less hassle than 70deg.
Have you tried an alternative flux? I don't use it but Steve swears by Powerflow - easily obtainable form sources such as Screwfix
Jim P

[Natalie Graham]

One possible problem is that with largish lumps of brass it's possible to melt the solder without getting the brass to a high enough temperature for it to stick.

That sounds to me like it could be the issue, especially if you are using the iron to melt the solder directly rather than heating the joint and letting the joint melt the solder, or even worse, taking the molten solder to the joint on the tip of the iron. If you are too wary of melting the white metal parts you could be not getting enough heat into the joint. You end up effectively glueing the parts with the solder (which is really how the 70 degree stuff works) rather than properly soldering them and as you are finding the solder then does not bond to the metal.

[David B]

Have you tried an alternative flux? I don't use it but Steve swears by Powerflow - easily obtainable form sources such as Screwfix

Thanks for the thought, Jim, but no. I wouldn't touch Powerflow. I used it when I re-started the hobby a few years ago and found it very difficult to clean off and get rid of the residue. One kit which I got part way through and have left now for 3 years - I am waiting for a certain manufacturer to come up with the promised detailing kit - now has green patches where the power flow was used in spite of my carefully cleaning the kit before laying it aside. I'm glad I hadn't finished and painted it.

[David B]

One possible problem is that with largish lumps of brass it's possible to melt the solder without getting the brass to a high enough temperature for it to stick.

You may well be right, Allan (and Natalie). I have just got some white metal to stick to an expanse of brass using 100o by tinning the white metal with the solder and using my RSU very near it but on the brass. As soon as I saw the solder melt, I removed the heat and the white metal is fine. I just could not get it to take using an iron.

This has a downside, though. I was soldering on to a wagon floor and although I got the white metal to stick on to the top, the brake gear fell off the other side! One has to laugh.

[billbedford]

Have you tried an alternative flux? I don't use it but Steve swears by Powerflow - easily obtainable form sources such as Screwfix

Thanks for the thought, Jim, but no. I wouldn't touch Powerflow. I used it when I re-started the hobby a few years ago and found it very difficult to clean off and get rid of the residue. One kit which I got part way through and have left now for 3 years - I am waiting for a certain manufacturer to come up with the promised detailing kit - now has green patches where the power flow was used in spite of my carefully cleaning the kit before laying it aside. I'm glad I hadn't finished and painted it.

PowerFlow is water soluble, it says so on the pack. The easiest way to clean it is to put your model in a plastic tub and pour very hot water*, straight from the kettle, over it. Do this after every soldering session and you won't get the green patches.


* not recommended if you have used 70º solder.