Soldering the Difinitive How To Wiki

[Efram von Rosengine]

First things first.  While these processes have been practiced for centuries , they do require the use of equipment and materials that are inherently dangerous, and hazardous.  Safety of life and property should have first priority. read all instructions , data sheets, keep copies of material safety data sheets (MSDS) These are usually available from manufacturers web sites for down load, or they will email it to you for the asking. If you have children have an emergency plan , if you don't , have one anyway . When you go to buy a torch , the first item you will take off  the shelf is a FIRE EXTINGUSHER. if you can't afford both , get the fire extinguisher first,It's too late to run out and buy one when you need it!

SAFETY FIRST SAFETY FIRST SAFETY FIRST SAFETY FIRST SAFETY FIRST SAFETY FIRST SAFETY FIRST[/font]

Solders contain various metals including but not limited to Lead , Tin,Antimony,zinc,Silver,Copper,Cadmium, even Arsenic ( usually trace)  Cadmium, and zinc are the two most often causing metal poisoning, Cadmium can be misdiagnosed due to cold or flue like symptoms and not being a common occurrence. (cadmium is used in hard silver solder,it is no longer allowed , but you might possibly find some if you are a scrounger ..beware! ) Good ventilation and a good properly fitted respirator, with appropriate filters, is mandatory especially when polishing or grinding.

I have been soldering in soldering in many different fields, from plumbing to jewelery  to musical instrument repair. The first problem most people have stems from not knowing how to solder properly in the first place. While the general idea is the same , the techniques applied are different. What you would do for water pipes is not appropriate for jewelery, instruments or artwork ( unless that is the look you want to achieve for effect) . Questions often arise on how to remove the mess of a sloppy job, and it can happen to the best of us.

For soldering the metal must be clean , that said applying abrasive to the metal may hinder as much as help. solder will flow better along the lines of abrasion rather than across them. Not a huge issue for plumbing but for high quality decorative work. for that very fine abrasive, paying attention to the direction of the lines, the other is actually polishing with a buffer before you attempt the process. this will require critical cleaning to get embedded polish off the surface that will hinder the flow.

The  next biggest problem stems from feeding wire into the joint , this will always leave solder showing near the joint. This can be controlled by carefully tinning the areas first, flux, heat , apply a SMALL dab of solder then wipe to a thin film with a cotton rag ( old cotton t shirt) , a cotton swab for the inside of small holes. this must be done to both surfaces.  rather than feeding wire , flatten your solder, with a clean preferably, polished face hammer. A dirty hammer will embed crud in the soft metal causing more problems.

Place the small clipped pieces of solder strategically at the joint in places that are not seen or the easiest to clean up. Apply heat to the joint away from the solder, heat gently and allow the solder to flow toward  the heat source. Heating the joint directly with the flame can cause oxidation that will hinder flow. The best advice for cleaning up a sloppy solder mess , is not to create one in the first place.

Cleaning up ,and it is inevitable, as mentioned somewhere above can be be achieved by hot wiping , but this will spread the solder over a large area. if there is a large blob above the surface scrape it off with hobby knife or small chisel like scraper before hot wiping. Once it is reduced to a thin film it can be buffed off with emery compound or tripoli . If you pay attention to your feed points these areas should be small and easily accessible to the buffer. cI have been soldering in soldering in many different fields, from plumbing to jewelery  to musical instrument repair. The first problem most people have stems from not knowing how to solder properly in the first place. while the general idea is the same , the techniques applied are different. What you would do for water pipes is not appropriate for jewelery, instruments or artwork ( unless that is the look you want to achieve for effect) .

For soldering the metal must be clean , that said applying abrasive to the metal may hinder as much as help. solder will flow better along the lines of abrasion rather than across them. Not a huge issue for plumbing but for high quality decorative work. for that very fine abrasive, paying attention to the direction of the lines, the other is actually polishing with a buffer before you attempt the process. this will require critical cleaning to get embedded polish off the surface that will hinder the flow.

The  next biggest problem stems from feeding wire into the joint , this will always leave solder showing near the joint. This can be controlled by carefully tinning the areas first, flux, heat , apply a SMALL dab of solder then wipe to a thin film with a cotton rag ( old cotton t shirt) , a cotton swab for the inside of small holes. this must be done to both surfaces.  rather than feeding wire , flatten your solder, with a clean preferably, polished face hammer. A dirty hammer will embed crud in the soft metal causing more problems.

Place the small clips of solder strategically at the joint in places that are not seen or the easiest to clean up. Apply heat to the joint away from the solder, heat gently and allow the solder to flow toward  the heat source. Heating the joint directly with the flame can cause oxidation that will hinder flow.

Cleaning up as mentioned somewhere above can be be achieved by hot wiping , but this will spread the solder over a large area. if there is a large blob above the surface scrape it off with hobby knife or small chisel like scraper before hot wiping. Once it is reduced to a thin film it can be buffed off with emery compound or tripoli . If you pay attention to your feed points these areas should be small and easily accessible to the buffer.

Think your way through the process first, rather than jumping right in. Plan your entrance and exit strategy before starting, think about what might go wrong, and how you will fix it. This will be the greatness help in improving your work  (believe me before you put a torch to a flute or Saxophone that a client paid $2000 to $8000 for you will do this)

I expect this to be an ongoing thread, and invite other knowledgeable technicians to post hints and tips, we all do things a bit differently for similar results.It is also difficult to toss out thirty plus years of experience is thirty minutes. A bit of your background and field of application will help sort out techniques. I started this thread as a general help section  attempt to get a more concise discussion on soldering processes, and techniques rather than various project how to's. Questions are welcome .

have fun and be safe
Cheers

[heavyporker]

Thank you for this advice. I was planning on taking up some soldering when I start crafting in earnest in a few weeks.

[Videodrome]

Interesting. 

I finished a class in MIG welding and looking into using it for Steampunk projects.  But depending on the project I'm also thinking of soldering. 

I've never soldered with a flame before though I've only used a soldering iron. 

[Narsil]

I think its best to treat electrical soldering and 'structural' soldering as two entirely separate processes, although the physics and chemistry of what's going on is pretty much the same the approach is significantly different and experience of electrical soldering alone can give you a somewhat skewed view of how it works.

I suspect the most misunderstood aspect for beginners is that the idea is not to use the solder as hot  glue, in fact in almost all cases you want to avoid heating the solder directly at all. It is the joint which needs to be heated, if the joint isn't at the right temperature then nothing you do will result in a good join.

The other misapprehension is the more solder the better, in fact, as with adhesives you will get the strongest joint from the thinnest possible layer of solder. Ideally the solder should form a thin layer only between two areas of base metal which are already virtually touching, avoid using it to fill large gaps, at least when the solder is expected to take all of the load in the joint.

[Efram von Rosengine]

@ Vidiodrome: Welding and Soldering , as you know are quite different, you may however find that for some larger projects neither welding or Soldering are appropriate, but a third process called brazing or silver brazing may be a better choice. This process in mos cases is done with a torch, and one fed with oxygen at that.  This process is obviously hotter and accomplished with harder alloys, resulting in stronger joints.

My plan was to eventually get around to all of these techniques eventually.

[Efram von Rosengine]

Narsil has some very good points Electrical and Structural should be treated differently, when you have been doing both for as long as I have you tend to take it for granted , as it tends to be second nature , rather like riding a bicycle.

   Reply with Quote

"I think its best to treat electrical soldering and 'structural' soldering as two entirely separate processes,...."

I plan to add an electrical section to this thread as time allows

"... in fact in almost all cases you want to avoid heating the solder directly at all. It is the joint which needs to be heated..."

This is one of the key points, directly heating the solder usually causes oxidation to the solder and the parent metal which hinders flow. heating the joint away from feed point while it is covered in flux will allow it to stay clean and the solder will flow efficiently.

" Ideal the solder should form a thin layer only between two areas of base metal which are already touching, avoid using it to fill gaps. "

This point stresses  the importance of having a good tight fit at the joint, although not so tight that the solder wont flow. there are cases however where allowing a fillet to build up around the joint will add strength. It should be understood that you don't want to force a large fillet , but rather let it build to what it's natural surface tension creates and no more by adding solder and applying heat uniformly to control it . this technique is less appropriate for decorative work , but more so for items requiring maximum strength and durability. With practice this can be done neatly , and is usually applied to surfaces joined at right angles.A similar technique can be done with adhesives, and there additives made specifically for that..but I digress..

[Efram von Rosengine]

ROHS and the future.

Some will be aware , others not about a new worldwide directive called ROHS , or "Restrictions On Hazardous Substances"  I bring this up here because it applies to soldering alloys. Historically solder was usually an alloy of tin and lead , in varying proportions to control the hardness , strength , and flow properties. This new directive mandates the removal of lead from the alloys. This was done largely due to the prolific use of solder in the electronics industry, and the problem of what to do with discarded electronics. there is also concerns on the manufacturing side due to lead vapors and dross (dross is the oxides and dirt that float to the top of molten solder,and is obviously highly contaminated with lead).

For your concerns , this means that lead solders will very soon in not already become unavailable. The lead free solders require more heat , and are slightly more difficult to use, although they have been in wide use for decades now, Stay Brite being one of the original brand names, the same techniques apply. The novice will learn with these new materials, the experienced will " feel " their way through the differences.

Just in case it isn't said enough , wash your  hands before eating , smoking etc when handling solders , even the lead free varieties. Keep work areas cleaned, and properly dispose of  waste materials and rags. Many recycling businesses are now collecting E-scrap or electronic waste , sometimes referred to as "WEEE" or waste electrical or electronic equipment . This is ideal for disposal of soldering scraps , as these companies are recovering the metals for reuse.

will next try to prepare a bit on heating sources

[Dr.Nautilus]

Thought I would revive this topic and ask for advice.  I am lousy at soldering and trying to improve.  My main trouble seems to come from not knowing how to secure the two pieces together while soldering.  How, for example would you clamp or secure a brass pipe to another surface while using the soldering torch?

Dr. Nautilus

[Narsil]

Annealed iron wire is very useful for holding pieces together while you solder them, use different gauges for different jobs. Reverse action tweezers (ideally with insulated handles) are also very useful for holding small pieces.

Also handy are assorted bits of hard and soft fire-brick which can be used to prop things up. A 'welders finger' can also be very useful http://www.flickr.com/photos/12493141@N07/3341446758/#

Often in welding and soldering jobs you end up improvising special jigs for specific jobs. In brazing this is slightly complicated by the fact that you tend to put quite a lot of heat into the whole of the work so you need to be careful that nothing is going to melt, catch fire or suck too much heat out of the work.

If something is really tricky to hold in place it can sometimes be an indication that you might need to rethink the design of the joint, perhaps by adding small pins etc to improve the mechanical fit.

 

[Neibelungen]

Some very usefull information and tips  for working with soft and hard soldering.  (tin/lead  and silver soldering).

I did notice however that there was no  mention  of fluxing a joint.   Though not so much a problem with some soft solders that come with fluxes cores,  even at relatively low (150-200c ) temperatures the metal will  oxidise before the solder has started to  flow and will prevent the  joint forming  properly.  Flux serves the role to  prevent this and  allow the solder to penetrate and join the metals.

Liquid or paste fluxes are available (such as Baker's Fluid or Power Flow flux pastes) for  low temp  soft solders,  while  borax  (or  Johnson Mathey Easyflow  or Tenacity) are suitable for hard solders.  Baker's works better  on  leaded solder,  while  Power Flow seems better with higher temperature lead free  solders  in my experience.

Interestingly,  hard solder joints work  best with tight push fit gaps  of about  0.3mm max, while soft solder will  work  effectively up  to 1.5mm gaps,  having  greater ability to  cross gaps and 'fillet' between parts.

Cleanliness  of the joint to is essential.. while sanding  helps,  simple wire wool  or a light pickle  in  dilute acid  or safety pickles  are essential.

It's also  worth bearing  in mind that  both hard and soft solders are available  in different  melting temperature ranges and thuse complex sequential  soldered joints can be built up on  parts with more than one or two pieces.