Don't Throw Solder Away

Introduction: Don't Throw Solder Away

About: I'm Chandra Sekhar, and I live in India. I am interested in electronics, and building small one-off circuits around tiny chips (the electronic kind).

Save it, and cast cool solder sculpture with it. Save all that lead from polluting the environment.

In short, Go Green.

The picture shows the result of my experiment in casting a solder ingot: inside the mould its says "instructables" but sadly, solder does not take details very well.

The movie shows the process: the loose solder in a stainless steel dish is heated and stirred with a hot (50W) soldering iron, and then poured into the mould.

I have gotten into the habit of saving all the solder that comes my way, and I keep a receptacle (with lid) on my table for this purpose. When it gets to a respectable amount it is cast into some shape and stored. Some day I might attempt making a really big sculpture with reclaimed solder.

Lead is not poisonous. The compounds of lead are, however. If you keep all the lead containing alloy that comes your way as the metal, in some pleasant shape, cast or sculpted into some form that is pleasant to the eye, you will be helping the environment by keeping at least some of its potential pollutants at bay.

Start saving your solder today. Read on to find out how.

Step 1: Scrounging for Solder

It all started when I got interested in electronics as a poor student. I saved up all my pocket money to buy a soldering iron and a few components. Solder was expensive. I decided to reuse solder.

All this was after I had tried wiring up a few circuits without soldering. Twisted connections were no good. They tended to loosen up when components were added or changed.

So I started scrounging solder from wherever I could. From the bases of old light bulbs - this was hard to melt, due to it being mostly lead, but it could be used after mixing with the regular kind. I looked up why from books in the library, and so got interested in melting points of alloys and things like that.
If somebody gave me a radio to repair I would be sure to get some solder from inside that, too. I learnt how to make joints with the minimum amount of solder.

And kept on saving all the solder I could find.

That involved cleaning my desktop very carefully after a soldering/desoldering session, and brushing all the bits of solder into a tin. I made it a tin with a tight lid after accidentally upsetting it one day and scattering precious solder on the floor.

The key to succesfully reusing solder is the flux. I bought some rosin to use as flux, after the general wisdom of the practising electronicians of that age - those gurus who were capable of repairing radio sets, and made a good living doing so. They all were using blocks of rosin at the bench. It was solid, smelled nice when heated, and the residue was not corrosive. There was a knack to getting it to the solder joint - it had to be carried on a heated screwdriver tip or copper wire.

The surest place to find rosin is the music shop. Rosin is the stuff violinists rub their horsehair bows with so that it makes squeaky sounds when they rub it against stretched wires on that wooden contraption. Sure, there might be cheaper places, but if you want some, and do not know where to go to, try the music shop.

The rosin does to solder what soap does to water - it makes the solder flow easier, by reducing the surface tension. It also reacts chemically with the oxides of the tin and lead, and turns them back into metal again.

The picture shows a collection of loose solder, as discharged from inside my desoldering pump.

Step 2: The Desoldering Pump

One tool you can't do without is the desoldering pump. This is a suction pump with a teflon nozzle. It sucks the solder into itself when its button is pushed, and discharges the solder out when its plunger is pressed in to make it ready for the next operation.

The video shows the pump being used to suck away solder from two joints on a printed circuit board. Several operations are required to desolder one joint, and the repeated pumping action necessary can get to be tiresome after a while.

Step 3: The Desoldering Wick

Sometimes it might be easier to use a desoldering wick. This is copper wire, braided and impregnated with flux. Heat it, hold it against a joint and it will pull all the solder into itself by capillary attraction.

The video shows the wick in action.

Step 4: Pumping the Wick

It is possible to use the two together. When the wick is saturated with solder, it has to be thrown (shudder!) away. I did not want to throw any solder away. I used the pump to extract the solder from the wick and save it in my solder bin.

The video shows my pump in action on the wick.

Step 5: Molten Solder Is Hot

So take care. It can settle on your skin and burn it through, if you accidentally spill it. If the material of your mould is damp or contains inclusions which break down at that temperature - an explosion of solder could result. The fumes resulting from solder and flux are hazardous.

Therefore, do this in a well ventilated area, and wear protective clothing and eye protection. Preferably, do this outdoors in a clear area.

I get solder as a byproduct when extracting components from old printed circuit boards. Most of those I have is of the pre-surfacemount era. The components on those boards do not stand up very well to getting heated up to the melting temperature of solder, so extracting them individually with soldering iron and wick and pump is the method of choice.

I have found that clear plastic bottles with the top cut off fit well into one another and make stackable containers for the extracted parts. The contents remain visible, which saves on the labelling.

So, start reclaiming those components and, of course, SOLDER, from those old boards, stay safe, and




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    86 Discussions

    If you really want to help the environment, collect tire weights that have fallen off of vehicles while you enjoy a long walk. All that lead is oxidizing along the roads and washing into our water supply. just a thought.

    2 replies

    That's easier than desoldering for sure. 20,000 tonnes of lead per year comes from the weights. Lead may be phased out in certain places for the weights.

    now that is a great idea I see those things everywhere whenever I go for a walk around town. I had no idea they were lead, but did wonder about them.

    any tips for desoldering a circuit board all in one swoop? I'd put it in the oven at 500 F, but I cook food in there! And I'd like to not mess up the components.

    10 replies

    Sometimes people use microwaves for solder reflow, so I am assuming that someone could devise a method to actually suck off all of the solder.

    DO NOT use metal things in microwaves! all kinds of things will happen; all of which will be far from heating- Microwaves heat only water they're designed that way.

    Umm, I think you might be mistaken.  Trust me (or don't; try ityourself!), semiconductors won't last long in a microwave oven :-) 

    But what _is_ cool in a microwave oven is a grape cut in half, thenslit again.  Search youtube for Grape and Microwave; it's quiteentertaining and actually works!

    I actually have not used a microwave oven befor for the purpose I described, so you are probably right. Microwave radiation being introduced to metals is not such a good idea. I just recall at the end of my memory reading something in instructables about desoldering using microwave. Most likely not a reliable source.

    i've never heard of using a microwave, but I have used a cheap $20 walmart toaster oven.

    heat up the component using a blowtorch or a bunsen burner or just your stove. It won't mess up your stove

    There are hot air soldering irons on instructables, but in most cases to melt solder you actually have to touch the joint with heat, not just blow on it.

    The solder i use has 4% silver content... i never throw it away! Now, if i could just find a reasonable way to separate the silver out...

    2 replies

    Would this work?

    No doubt the metal in the alloy melt at different temperatures, and has a different weight. How about melting the scrap in a crucible that has a way to drain off the heavier metal at the bottom? You may have to go through severe runs to get to,and refine the silver. Just guessing on my part


    2 years ago

    Thanks.. i was myself wondering if collecting the bits of solder and resuing them was feasible. but now that i know at least one other person i doing it with ease, off i go to save my solder

    You are incorrect. Lead is quite toxic, not just in the case of children who eat it.
    Adults can have toxic results after years of inhaling the stuff (people who have worked around munitions show significant pathologies). Here is just one link to toxic effects of long term lead exposure in adults.

    Why use lead solder at all? There are many good lead free solders on the market. Digikey is a great source. Lead based solders are not just bad for the environment, they are bad for the user. Electronics containing lead are now illegal in many countries that implemented RoHS (Restriction of Hazardous Substances) compliance requirements in July of 2006. For more details see