Mold on soldering sponges

[golden_labels]

I”m a wire wool user and have little experience with wet sponges. Since sponges are kept wet for extended periods of time, even when not used, do they grow mold?

[Ian.M]

They shouldn't be more than moist, and typically dry out overnight so mould is rarely a problem.   Maybe if you have a sponge in a container with a lid in a portable soldering kit and don't wash it out and let it dry after use.

[pcprogrammer]

My old weller station had a sponge and I have never seen mold on it. The sponge, even when quite wet, still dries up overnight when left in the sponge holder. I used to have a bottle of water on the bench to make it wet again.

Now with my Jabe UD-1200 station I switch to using the wool too. 

[jpanhalt]

I use leaded solder.  Never had a problem with mold.  If you use glucose as your flux, you might.

[golden_labels]

Thanks!

Nice glucose joke, but unfortunately doesn’t work. Glucose is flying all over your apartment right now and it’s sufficient to sustain efficient life forms like mold.

[calzap]

Heavy metals, in sufficient concentration, inhibit the growth of most cells including fungi.  On my ranch, one building has an exposed strip of zinc near the peak of the roof.  Have never had moss grow on it, but moss does grow on the roof of an adjacent building with no zinc strip.  Paints containing tin have been used on the bottom of boats to inhibit the growth of algae and other marine organisms.  So, lead, tin, copper in a sponge … no mold.  Don’t use it for doing the dishes though.

Mike

[Bud]

You kill the mold with temperature when you wipe the iron tip 

[u666sa]

You can't be wool user or sponge user, you need both. If you using one over the other that means you have a cheap solder station, or expensive solder station which wanted to charge you for extra stuff, but not a good solder station which comes with both build into iron stand. Both wool and sponge gets replaced every several months, so you never get any molding issues. You don't even get corrosion underneath the sponge, because it dries up overnight.

[janoc]

If you have mold on the soldering sponge then you should probably not solder in a steamy bathroom with poor ventilation.

Also, the sponge needs to be moist, not swim in water, so, as many said already, it will dry out in a few hours anyway. I have never seen mold on one of these.

[pcprogrammer]

You can't be wool user or sponge user, you need both. If you using one over the other that means you have a cheap solder station, or expensive solder station which wanted to charge you for extra stuff, but not a good solder station which comes with both build into iron stand. Both wool and sponge gets replaced every several months, so you never get any molding issues. You don't even get corrosion underneath the sponge, because it dries up overnight.

My soldering station does have both, but have not used the sponge since I got this station. The wool does a perfectly good job in keeping the tips clean, so why should I bother with wetting the sponge?

[eleguy]

I have never seen mold on my sponges but still I keep on using distilled "battery" water just in case.

[Terry Bites]

Stop using beer to wet your sponge!

[coppice]

I have never seen mold on my sponges but still I keep on using distilled "battery" water just in case.

Distilled water will have no effect on mould formation. Mould spores are in the air in large numbers, settling on the sponge all the time. It might reduce algae formation.

[coppice]

Stop using beer to wet your sponge!

You mean people are using the wrong kind of IPA?

[GLouie]

I also have never seen mold/mould or other growths on my soldering sponges either, over many decades. And I use tap water. Sometimes I even keep a water bottle on the bench to rewet the sponge and not have to go to the sink. I don't seem to even have a problem with anything bad I can smell in the water bottles after months. However, I don't drink from that bottle.

[Xena E]

I must say, I did think I was seeing mould on my soldering iron sponge at work the other day, but after I put my spectacles on, I realised It was Bob's Stilton sandwich I was stabbing with my Metcal.

Regards,
X

[u666sa]

[Bud]

That is not mold, you have same carbon stuff on your steel wool.

[richard.cs]

I've never had a sponge go mouldy, but plenty of water bottles go green with some kind of algae. A colleague used to add IPA to the bottle of soldering iron water to stop that growing.

[golden_labels]

I wasn’t expecting this question to bring so many responses. Since it did bring some discussion, a few reflections from me. Not to deny the no-mold camp, just because I can’t stand somebody being wrong on the internet.

Heavy metals may be toxic to life, but the effect is localized to where they occur. I doubt they’re distributed across the entire sponge. I would expect to see them mostly in the middle and around the top.

Temperature kills mold, but it’s a localized effect.

The sponge is indeed moist, not being drowned in water. If the latter was the case, mold wouldn’t be a problem. Mold doesn’t thrive under water.⁽¹⁾

I don’t know why is richard.cs’s friend keeping water in bottles, instead of using fresh water from tap, but I’m not sure if mixing fuel and hot solder tips is a good idea. On the other hand probably not a problem: IPA boiling point is lower than that of water, so it evaporates first, and also water is good at stopping fire.

⁽¹⁾ Except some species living inside animals. But all soldering sponges I’ve seen in my life seemed pretty dead.

[jpanhalt]

Heavy metals may be toxic to life, but the effect is localized to where they occur. I doubt they’re distributed across the entire sponge. I would expect to see them mostly in the middle and around the top.

Perhaps you overlooked the fact that heavy metals by themselves are not toxic until they are oxidized and can be absorbed.  Lead and tin oxides will disperse throughout a sponge.  The same principle applies to using zinc or copper strips at the crown of a roof to prevent mold from growing toward and at the eaves.

[ebastler]

You can't be wool user or sponge user, you need both. If you using one over the other that means you have a cheap solder station

This statement would be much more convincing if you gave some reasons. When do you specifically need the sponge, when do you specifically need the wool? Or did you mean to say that you need both in order to demonstrate that you could afford a "pro" soldering station? 

[pcprogrammer]

You can't be wool user or sponge user, you need both. If you using one over the other that means you have a cheap solder station

This statement would be much more convincing if you gave some reasons. When do you specifically need the sponge, when do you specifically need the wool? Or did you mean to say that you need both in order to demonstrate that you could afford a "pro" soldering station? 

I'm still waiting for an answer for this too. 

[golden_labels]

I wasn’t touching the “both required” part, but it would be nice to hear the reason. I can’t recall from the top of my head anybody using both.

In high school times my first, cheap soldering iron was cleaned with toilet paper. Not a recommendation. But the tip was shiny, clean, and working. So if that worked, it sounds weird hearing one needs both a wet sponge and wool.

[richard.cs]

I don’t know why is richard.cs’s friend keeping water in bottles, instead of using fresh water from tap, but I’m not sure if mixing fuel and hot solder tips is a good idea. On the other hand probably not a problem: IPA boiling point is lower than that of water, so it evaporates first, and also water is good at stopping fire.

Every lab I have ever worked in has had an old fairy liquid bottle* full of water for squirting on the sponge when they get dry. Once it's empty (a week or two) someone takes the bottle with them to the kitchen or the gents to refill it. I don't think I've ever worked in an electronics lab with a tap.

*Dish soap, ubiquitous in the UK. The bottle has a nice cap design that makes it quite suitable for this purpose.