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DJones
03-10-2010, 09:23 AM
OK, how do I clean a fitted steel part that refuses to tin. I'm using Brownells HI-TEMP Hi-Force 44 and copper bond flux. My first try ended in total disaster, after talking with a Tech at Brownells we decided that the flux was not working. I later checked and discovered the flux has a one year shelf life. Replaced the flux and the new bottle works much better, but I'm still having trouble with getting the parts to tin, very spotty coverage. I did some practice runs on scrap pieces with low temp Hi-Force 44, common soft solder and some silver just to check myself and had no problems. I tried the High Temp, Hi-Force 44 on my parts and later a test piece and still no go. I'm thinking it's a cleaning problem. I've scrubbed both parts with cleanser and water and then denatured alcohol. I've tried to think of what I've done that would have contaminated the surface of both parts and how to correct it. I need to clean the parts with changing the dimensions significantly.

Any thoughts would be appreciated.

mwechtal
03-10-2010, 12:59 PM
OK, how do I clean a fitted steel part that refuses to tin. I'm using Brownells HI-TEMP Hi-Force 44 and copper bond flux. My first try ended in total disaster, after talking with a Tech at Brownells we decided that the flux was not working. I later checked and discovered the flux has a one year shelf life. Replaced the flux and the new bottle works much better, but I'm still having trouble with getting the parts to tin, very spotty coverage. I did some practice runs on scrap pieces with low temp Hi-Force 44, common soft solder and some silver just to check myself and had no problems. I tried the High Temp, Hi-Force 44 on my parts and later a test piece and still no go. I'm thinking it's a cleaning problem. I've scrubbed both parts with cleanser and water and then denatured alcohol. I've tried to think of what I've done that would have contaminated the surface of both parts and how to correct it. I need to clean the parts with changing the dimensions significantly.

Any thoughts would be appreciated.
I have at times used a Stainless Steel brush on the hot part. I just pull the torch away, and scrub a few strokes, put the torch back on, and maybe add some solder. With ordinary 50/50 Lead/Tin solder it has worked for me.

RWO
03-10-2010, 01:34 PM
I have always used the regular Hi-Force 44 solder and Comet # 4 flux. I have never had a problem with any kind of steel, brass, etc. Comet #4 has no shelf life problem. I have a big bottle that is at least 10 years old and it still works perfectly.

As for activating your surfaces to take the solder, dipping the degreased parts in 50-50 muratic acid-water solution for 20 or 30 sec with make them chemically clean and ready to solder. Just be sure to neutralize the dipped parts in a baking soda -water solution afterwards as they will rust in a flash.

RWO

rolland
03-10-2010, 04:40 PM
If you are using oxy/ace torch you may be too hot I have always found that you clean the part and get all the oil out of it ( I soak in acetone). after cleaning flux the parts and apply indirect heat don't put the flame any where near the surface you want solder on. tin the part and wipe with some flux I
use a "Q" tip soaked in flux to wipe after the solder melts so you have a good clean tinned surface. clamp the parts together and heat and watch for the solder to flow if you need a little more then you can add solder you should get a capillary action .
I have found the biggest problem with silver solder is you can easily get it too hot then it will bead up and not work. I use map gas for most of my silver soldering and stay away from the oxy/ace as it gets too hot to quick (at least for me.
Hope that makes sense, of course it does to me but then I wrote it :rolleyes:

bob_s
03-10-2010, 07:07 PM
If your original flux was old, was the solder also old?

Could be oxides on the solder itself, try cleaning it!

DJones
03-10-2010, 07:43 PM
Thanks for the replies.

I am using my propane torch and heating the part and touching the solder to the part. I am quite sure I'm not getting the material too hot as there is no beading, the solder spreads, but simply refuses to penetrate/displace the flux and tin the surface. The solder is a fresh batch.

I've not used this solder before but want to use it for it's high strength, 38,000 psi, and the temperature range, 650 degrees, will allow me to go back and soft solder some of the remaining parts on without having to fixture up quite so tight to keep this part in place.

I'm no expert, but I don't normally have any significant problems when soldering or brazing. I'm still thinking it is a contamination problem, but can't put my finger on what I did that is causing the problem or how to clean it well enough to get the solder to flow and stick.

I guess I'll just keep trying and see what develops.

Again, thanks for the replies.

Stepside
03-10-2010, 09:15 PM
Whenever I use a silver bearing solder I dip the solder in the same flux I use on the parts. I also use a barely carburizing OxAcet flame. As to "too hot", never stop moving your flame and put more of the heat into the heavier part.

38_Cal
03-10-2010, 10:24 PM
Try taking some new 320 grit paper and wrapping it around a wood block shaped to the area you're trying to tin. Lightly sand the area on the hot part, quickly flux it and add solder. You can get things too hot even without the solder beading...the flux will essentially burn in and contaminate the part rather than clean it.

David

Kibby
03-11-2010, 05:16 AM
I also soak in acetone. Preheating, and a quick wipe with a clean wet cotton rag also works to remove any residue. It literally steams any dirt right off.

DJones
03-12-2010, 06:19 PM
Well guys I hate to admit it, but I finally gave up, cleaned the parts and used the lower temp, 475 degree Hi-Force 44 instead of the 650 degree version. Both parts tinned easily and the parts went together with no problems. I guess I'll never know what was wrong, but I couldn't get the higher temp stuff to work no matter what I did.

Thanks for all the advice. Sorry that I can't report success with the original problem.

38_Cal
03-13-2010, 11:21 AM
Contact Brownells, let them know about your problems making the stuff work, and have them take it back. It sounds to me like you did everything right, but the stuff just didn't work for you.

David

ironmonger
03-28-2010, 01:10 PM
I just recently retired from my day job, plumbing, after 41 years. Soldering has always been a part of that craft, and what I learned there may well translate to what you were having a problem with. It may also explain why the lower temperature solder worked when the other failed.

Some years ago I took a class sponsored by the copper institute. We soldered copper to copper, copper to stainless steel aluminum to copper and aluminum to stainless. This was all accomplished with what we call silver bearing soft solder, which is a lead free variant. This could also be accomplished with 95-5 solder, which is 95 % tin and 5% antimony or 50/50 tin lead solder. We used 'Nokorode' flux for all of these joints. The Oatey products are very good also. The Laco fluxes are very active and work well too. CLEAN BEFORE AND AFTER!!!

All fluxes have a limited 'time at temperature'. With the aluminum and stainless we used indirect heat and massaged the flux with fiberglass flux brushes while we heated the surface and added the solder while brushing to 'tin' the surfaces. The active 'cleaning' chemicals which remove the oxides and hold them in suspension will break down or be 'used up' if the temperature is held to long. The oxide eaters will react with the air born oxygen as well as the oxides on the metal.

It is important to mechanically clean the surfaces, flux them and heat them with out dallying around while tinning them. Once they are tinned a small amount of flux with mechanical pressure and heat will bond the pieces. My guess is that your flux failed, whether due to to much time heating, impingement of the flame causing the flux to overheat or old flux. I have very little experience with liquid fluxes used for soft solder, most all of the fluxes used are 'paste' fluxes.

The paste fluxes are now available in water soluble and oil based varieties. Regardless of what you use after the joint is made you must remove all traces of the residual flux.

When adding solder to a capillary joint, and after preheating, heat the joint where you are adding the solder until the solder begins to flow and then continue to add heat along the length of the joint and maintain the heat where ever you add solder. If you solder in a linear fashion, the flux that may be trapped in the joint will flow out ahead of the solder entering the joint, thus preventing flux 'pockets' inside the joint.

The solder will not flow where the temperature is to low. It is a balancing act between sufficient temperature and staying in one place to long.

'The craft so long to learn, and life so short'
Paul

argon99
04-13-2010, 03:05 PM
A propane torch with mapp gas just will not work. It takes way to long to get the parent metal up to temp, probably never does. To prove this to yourself there are temp sticks ( they are called Tempilstiks do a google search for them. They are cheap, around ten bucks per temp). These are markers that melt at a specific temp. Put different temp markings next to each other and heat with the propane torch using mapp gas. My guess is you are only getting the temp of the metal up to about 500 degrees. This is not hot enough for HI-TEMP HIGH FORCE 44 solder. But it is for regular HIGH FORCE 44. You need an A/O torch to get it hot enough.

And as a side note an A/O torch set is cheap. It will come in handy over and over again. It's well worth the expense. For example how much time did you spend on this one project? It would have been over and done with right away if you would have used an A/O torch.

PS
you can get the tempilstiks here: http://www.tempil.com/thumbnail.asp?cid=6

ulav8r
04-13-2010, 04:04 PM
A propane torch with mapp gas just will not work. It takes way to long to get the parent metal up to temp, probably never does.

Depends on the size of the parts. May be correct or not. If doing small parts propane may be plenty. Melting temp is about 650, propane flame is 3200 or more. BTU content and need is what determines if propane is sufficient.