Is cooled-down lead after soldering safe to touch?

Question

I’ve found one topic on this forum about this but it doesn’t answer my question fully.

From the information I’ve gathered, you should wash your hands after touching lead, even if it’s a cooled-down joint.

I make a keyboard, it doesn’t have a fully closed case, you can’t touch lead directly, but it has holes and it is open to air. Lead is kind of there and I want to take this keyboard with me everywhere. It will be in my backpack, on a train, etc., and of course it will shake and bump and all sorts of stuff.

My question is, how solid are lead joints? If the lead is not enclosed, does it pose any risk?

Answer 1

It's not clear what your concern is, or, how big the holes in your enclosure are; why mention them if you still can't touch it? I guess they are too small to reach through, but open to air. So maybe you were thinking it can emit spontaneously?

If you can't touch the lead, it's fine. It does not evaporate, it does not produce dust on its own, and even if so, it's only an ingestion hazard (mind, ingestion includes dust inhalation). It's not absorbed by the skin.

Regarding touch, it's only anything that causes material loss: abrasion, cutting, etc. Solder is very soft, soft enough that stroking it with your fingers typically leaves a black streak on you -- this should be washed away. That's all. Incidental handling is unlikely to be a problem (you'd have to really rub on it to get anything to see -- mind, invisible amounts should still be avoided). And with no contact, it's no problem at all.

I would be more worried about the keyboard's health itself, if it were so exposed -- all those electrical contacts would be prime ESD targets.

Answer 2

Yes and no. It's possible you contaminated some of the surfaces with lead during soldering if the solder was sputtering or the tip was way too hot, but wiping down the exterior of the keyboard with soap and water should be sufficient to take care of that.

If you do that I would consider the keyboard to be perfectly safe to use.

As others have said, the finished solder joints will not emit any lead if they don't get wet and corrode.

..However when the keyboard inevitably gets land-filled, the lead will be there, leaching into the ground water or otherwise contaminating the environment.

Lead free solder is totally usable with just a little bit more practice, so to me there's no reason to ever use the lead stuff, except maybe in life support applications where the absolute best material properties are required.

I would wipe down this keyboard and not worry about it, but I would get yourself a roll of lead free solder and a temperature controlled soldering iron for the future.