Introduction: Don't Throw Solder Away

Picture of Don't Throw Solder Away

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

Picture of 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

Picture of 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



burningsuntech (author)2007-12-09

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.

hanlin_y (author)burningsuntech2017-03-17

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.

Graydant (author)burningsuntech2015-01-26

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.

alexanderm (author)2010-11-20

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...

hanlin_y (author)alexanderm2017-03-17

Would this work?

static (author)alexanderm2011-10-10

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

queer1 (author)2015-11-09

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

DanaK15 (author)2015-10-25

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.

iwilltry (author)2007-08-18

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

n0ukf (author)iwilltry2008-03-25

even when lead is being replaced in electronics, anything made for the military still uses lead because of reliability of the connections. If you can find something that solders as easily as lead and has the same reliability in the soldered connections as lead, and isn't much more expensive, then let us know. Who knows, it might even make you rich. Personally, I think ROHS is going overboard about the hazards of lead-based solder. I've read somewhere also that the lead alternative solders have their own environmental problems, whether it's in the manufacturing process or whatever else.

etkoehn (author)n0ukf2014-03-11

Lots of things like ROHS is from lobbyist so that way they can sell their product. Lets face it a lot of stuff wouldn't have a chance unless the other was outlawed and the best way to do it is say it's harmful. But in my short time here I found most things to be harmful if not used properly

iwilltry (author)n0ukf2008-03-25

Lead based solders are only marginally more reliable than lead free solders. Everyone talks about tin whiskers that "sometimes" form but the difference in reliability is so small it is only important in highly critical applications (military, life support, outer space) where the consequences of a failure are huge. In 99% of applications lead free solders are just as good. I've been involved in electronics manufacture for the past 7 years. In 2006, we switched everything to lead free components and solders for RoHS compliance since many of our products are sold in Europe. Lead free solder takes a bit of getting used to since it looks and behaves a little differently, but we haven't had any issues with reliability. Whether the new solders are any better for the environment, I can't say for sure. But I'm pretty sure they're better for the guy doing the soldering.

fundash (author)iwilltry2010-08-23

I disagree :P I have been using lead-free solder for awhile, and recently I bought 60/40 lead solder, it becomes liquid it a lower temperature, so there isn't as much of a risk of overheating parts, and it seems to flow a bit better to, the fact is, I think leacd solder is better than lead-free solder! :)

iwilltry (author)fundash2010-08-26

I'm not sure what it was I said that you're disagreeing with. I agree with you 100% that lead based solders are easier to use. So are lots of harmful substances compared to their less harmful alternatives (don't get me started on acetone). What I meant when I said lead free solder is "better for the guy doing the soldering" is that it's less likely to harm you. Look up lead poisoning on wikipedia. It's probably not a big deal for the home hobbyist but if you solder for a living (or employ people who do) lead based solder poses a serious health risk. Given the amount of electronics that end up in land fills it also poses a wider health risk due to ground water contamination.

fundash (author)iwilltry2010-08-28

yea I know, but thats why they have things called "Fume Extractors" they suck up those nasty fumes and save your lungs! :D

9.6 Volts (author)n0ukf2008-10-11

If you don't like lead solder, there is something very wrong with you

waif69 (author)n0ukf2008-07-25

Actually due to EPA restrictions very few mil-spec electronics are made with lead based solder. Pure tin is a very common solder, however tin has been known to grow whiskers resulting in potential short circuits of the components.

pfred2 (author)iwilltry2012-02-04

Old post but I have to reply. You know that defense and aerospace contractors are exempt from lead regulations don't you? The law makers figure you can use the garbage but they reserve the rights to using the good stuff for themselves.

awang8 (author)iwilltry2008-12-21

Lead free soldering is very very difficult to melt on a ordinary iron and does not conduct as much as lead. If you're making military grade stuff you need lead or else it's just hobby grade.

lburrow (author)awang82011-10-10

I think most hobbyists aren't necessarily aiming for 'military grade'. A better way to put it might just be that your projects will not be as reliable without the lead.

DYLEGO (author)awang82009-02-01

Dude, how many of us are making military grade stuff? Also, lead free solder melts just fine. I use it with no difficulty.

awang8 (author)DYLEGO2009-02-02

It doesn't melt much on a normal iron. And what's better than proving your project is military grade?

wolf555hound (author)awang82009-03-07

Alien grade?

lburrow (author)iwilltry2011-10-10

Well... for one reason, lead free solders tend to form 'tin whiskers' sure your project works today but some number of months or years later a whisker forms a bridge and your circuits go up in smoke.

Try doing a Google search for 'Tin Whiskers' if you haven't already heard of them.

Also, lead free solders require more heat which even if it doesn't immediately break your components it might still reduce their lifespan.

There are plenty of ways lead has been used in the past which have resulted in too much lead exposure and poisoned people. I've known plenty of people that have used leaded solder for a lifetime with no problems and I have done so for a couple decades myself.

If you expose yourself to enough lead to cause a problem just by soldering components you are doing something very very wrong. On the other hand, if you want to build something nice that will still be functional decades down the road when you try to show it to your grandchildren then you do not want lead free solder.

Itsgoofytime (author)iwilltry2007-09-12

Lead free solder is better for the enviroment, but that's where the goodness ends. It is difficult to solder, becomes "sticky" and wont form up well. If you are using leadfree solder on surface mount components, you will see the development of tin whiskers, microscopic crystalline structures of tin that without the presence of lead can lead to these. They can cause shorts and mess up your experiment. Stick to Lead but make sure you save it and be careful with it.

cyber_meat (author)Itsgoofytime2008-03-26

I don't know what your talking about. I have used both normal and lead free solder and I have found silver bearing solder to work just as good on electronics. if you have trouble forming it that just means that you may not be heating up the solder or the parts connector enough. you should try turning the temperature up on your soldering iron just a little bit.

!Andrew_Modder! (author)iwilltry2007-12-09

thx, use non lead solder! Protest against lead! :-P .................word.

etkoehn (author)2014-03-11

would be great for casting bullets or sinkers

Machine (author)2013-11-23

That's a nice instructable, thanks for carefully explaining it to us. I'll stop wasting my solder and re-use it.

I have an old toaster oven that heats to 240 C and should be able to easily melt solder off PCBs. I think if I just put a stainless dish under the PCB the solder should melt into it and be collected that way. Any thoughts on that?

Emiliano Valencia (author)2011-10-31

"Lead is not poisonous. The compounds of lead are, however."
Lead IS poisonous, no matter if it's alone or in s Lead/tin blend.
That's why they tell you o wash your hands after doing some soldering.

pfred2 (author)Emiliano Valencia2012-02-04

So far lead hasn't poisoned me for the 40 years I've been using it. I think you're going to hurt yourself worrying about little stuff more than lead will ever hurt you. Unless you get in front of a speeding bullet made out of it or something.

NATIVEBOY (author)2012-01-23

metallic lead is very toxic in it's pure state, and in lead alloyies because it stays in bones for years because your body mistakes some of it as calcium and that goes into your blood. then lead stays in your muscles and fat's for months and it stays in your blood for weeks. if lead is in it's ore form it's very hard to absorb into your body.


orangetj (author)2011-10-23

... are you saying that the metal in most electronics is literaly dangerous to our health... no wonder the local hospital always fails health inspections

static (author)2011-10-10

In the event you can accumulate enough solder scrap, it also has cash value.

rgbphil (author)2007-08-18

Nice Instructable, I remember having lots of fun making toy soldier moulds out of plaster and casting solder into them to multiply my armies. Interesting comments about using violin rosin to help. I would recommend though a warning at the start of the instructable to make sure any casting/melting be done in a well ventilated area. Lead and resin fumes can be dangerous, there are a lot of problems in some countries with people taking old PCBs and melting them on hotplates to extract various metals. Also could you follow up the "Lead is not poisonous. The compounds of lead are, however." comment with a reference please...lead is usually regarded as hazardous so a clearer definition of what you mean would be handy. In either case, I would not assume any melting/casting would make pure lead, so another warning about possible compounds/impurities and toxicity would be helpful, along with washing hands afterwards and not using implements for preparing food....common sense I know, but some people don't have sense that is all that common. When making toy soldiers I used to coat the lead with paint and lacquer so bare metal was not exposed to the fingers.

neelandan (author)rgbphil2007-08-19
"bullets lodged in the body rarely cause significant levels of lead poisoning"
from the wikipedia
dagenius (author)neelandan2009-04-20

Why would it matter a corpse got lead poisoning or not??!!?

static (author)dagenius2011-10-10

So who goes around shooting corpses anyway? The living person about to get a fatal dose of lead may care a great deal

geekzerone (author)dagenius2009-09-16

not necessarily a corpse. Not all bullet wounds are fatal. Even bullets that are not jacketed with copper (solid lead, nothing else) rarely cause lead poisoning. Lead is a heavy metal, and takes time to dissolve in the body. Lead fumes, however, are rather easily absorbed into the body. That is why I work with a ventilation fan. Its just a computer fan hooked up to a 9 volt (or scrapped power adapter) and ventilation tubing. Works great for sucking away nasty fumes. Just put the other end near a window and it all goes away.

static (author)geekzerone2011-10-10

Not that I'm saying that the fumes associated with soldering aren't nasty, but they aren't lead fumes. The fumes are from the flux not the metal.

dagenius (author)geekzerone2009-09-26

fumes from "solder" are not actually lead fumes, they are flux vapors. that is why if you heat a joint too long it boils off the flux, which cleans the two surfaces, and you get a bad joint.

geekzerone (author)dagenius2009-09-26

the fumes do contain some amounts of lead. However, you'd have do a lot of soldering, and breathe the fumes a lot. The lead can build up in your body and once heavy metals enter your body they can be difficult to remove.

8bit (author)geekzerone2010-06-23

Can you prove fumes contain lead? I keep hearing that they don't.

JJrulz (author)neelandan2008-05-31

lol, gotta love wikipedia, i am sure that when you get shot your immediate thought is not "oh noes am i going to get lead poissoning?!?"

leebryuk (author)neelandan2008-02-22

I hate to say this, but Wikipedia isn't correct all of the time. Lead is toxic. It takes the place of other metals in biochemical systems. It is a particular problem when lead is ingested (oral or respiratory.) Yep, do not like your fingers when working with lead. Never, ever sand lead but filing away is OK. I think you get the idea.

RaNDoMLeiGH (author)2008-10-18

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.

dagenius (author)RaNDoMLeiGH2009-04-20

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.

nawg (author)dagenius2011-09-30

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.

scicior (author)dagenius2009-10-15

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!

dagenius (author)scicior2009-10-21

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.

About This Instructable




Bio: 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).
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