Mask for soldering fumes - Page 1
Forum section: electronics / general

author: tony359
author_rank: Frequent Contributor
timestamp: November 21, 2024, 11:04:57 pm
content: Hi all,I'm working on some PCBs which require quite some soldering, a few hours a week. In Summer, I have a 200mm duct and a VERY powerful extractor pulling the air off the boards. I keep the workshop door open so I create a flow of air which prevents fumes from being inhaled.In winter, when it's freezing outside, I set up a heat recovery system which draws 200L/m. The 150mm hose is ON the board with a rectangular adaptor. It sucks away the fumes pretty well. Still, because I am close to the board, I can smell the fumes a bit at times.It's likely minimal and maybe not dangerous.But if I wanted to wear a mask as well, what type of filters do I need? I'd like to avoid a massive face mask - though it might be unavoidable for those purposes. Anyways, is there a recommended filter I should look for? I am in the UK when it comes to available standards.Thanks!

author: Analog Kid
author_rank: Super Contributor
timestamp: November 21, 2024, 11:23:54 pm
content: I'd think that an ordinary cloth face mask, not even necessarily an N95 one, would be alotbetter than nothing.Aren't the fumes mostly flux anyhow? I mean, how much metal actually evaporates when you solder? My guess™ is not very much.

author: rhodges
author_rank: Frequent Contributor
timestamp: November 22, 2024, 01:08:28 am
content: I asked a 3M rep about fumes from dissolving sodium hydroxide into water and using a (I believe) N95 filter. The response was that the filter was protective for those fumes.I think the fumes from burning flux will be much larger, and easily caught by the N95 mask.But ask 3M for a better answer.

author: Analog Kid
author_rank: Super Contributor
timestamp: November 22, 2024, 01:42:58 am
content: BTW, in case folks wonder (I used to before I learned what they meant), N95 means "for non-oily particles, 95% effective against 0.3 micron particles".P100 means "for oily particles, 99% effective ...". (Why didn't they call them "P99" then?) Those are the best available.

author: Zero999
author_rank: Super Contributor
timestamp: November 22, 2024, 12:04:30 pm
content: I wouldn't expect a cloth mask to have any effect. The problem with N95 masks is they're uncomfortable to use for long periods and need changing regularly.Where I work, we use an extraction system, with a filter, which exhausts into the room, which isn't perfect as the pipe gets in the way. I just hold my breath when have to solder something closely.

author: tooki
author_rank: Super Contributor
timestamp: November 22, 2024, 03:49:00 pm
content: Quote from: Analog Kid on November 21, 2024, 11:23:54 pmNone. Soft soldering temperatures are far below the boiling points of solder — we generally solder at temperatures just above the melting point.**temperature of the workpiece, not temperature of the soldering iron tip, which is higher. But still far away from the boiling points of ordinary solders.

author: thm_w
author_rank: Super Contributor
timestamp: November 22, 2024, 11:47:11 pm
content: Cloth mask is not going to do anything.You could get "3M Formaldehyde/Organic Vapour Cartridge/Filter, 60925, P100" but as mentioned respirators are awkward to use, and for me get irritating after about 30min.Other option might be tweaking the setup to try to achieve something like a laminar flow hood. But if your face is that close, there is nothing to be done.https://www.weavertech.com/clean-room/laminar-flow-hoodsWe've discussed this topic many many times here before, most of the concern is the particulate. If you want to deal with the smell you can but its going to come at a large cost, as you'll constantly be going through activated charcoal or other material.https://sci-hub.se/https://doi.org/10.1093/annhyg/38.5.753

author: amyk
author_rank: Super Contributor
timestamp: November 23, 2024, 04:37:04 am
content: Unless you actually have an allergic reaction to the fumes, I don't think it's even remotely necessary.

author: tony359
author_rank: Frequent Contributor
timestamp: November 23, 2024, 08:44:58 am
content: thanks@thm_wI have emailed 3M, I am hoping for a smaller product - maybe disposable after a few uses. Though a respirator might work too, but hopefully a bit more compact.One other option - I know, I am overthinking - would be a respirator which simply gets air from elsewhere. I DO have fresh air coming in the workshop, I would just need to breathe that one. With a "one-way" valve, that might work and would not require filters. Again, overthinking.Another option might be to create a flow as you mentioned - so fume extraction at the soldering point to get 95% of the fumes and a larger flow (a big fan behind the workbench) which simply makes sure that no stray fume is getting to my face. Yes, those fumes would be just diluted in the workshop but it might work considering that I DO have fresh air coming in even in winter.

author: janoc
author_rank: Super Contributor
timestamp: November 23, 2024, 09:31:56 am
content: Quote from: tooki on November 22, 2024, 03:49:00 pmBoiling point has little to do with it. Things can and will evaporate at any temperature, just at different rates. That the matter liquefies and evaporates faster when hot/boiling is the consequence of adding energy to it, not because it is boiling. E.g. water can be simultaneously frozen and evaporating (= sublimation). Fortunately with metals their enthalpy is usually too high for them to sublimate at the usual temperatures but, for example, zinc is known to do that and is thus not suitable for use in vacuum.But you are right that the risk of inhaling metal vapors, be it tin, lead or whatever else in the solder alloy at common soldering temperatures is minimal. E.g. lead requires temperatures above 800 degrees Celsius to start to evaporate in meaningful quantities.This paper looks at the lead emission rates during lead production and there are some nice graphs and tables showing the emission rates depending on temperature:https://www.researchgate.net/publication/347098059_Increasing_Ecological_Safety_of_Lead_ProductionYou will see that lead can form vapors even at 330 degrees (about at the melting point of pure lead - and far below the boiling point) - but in minimal amounts.There have been similar studies done also in electronics production factories with regards to soldering fumes and the conclusion was that the metal vapors (not only lead - most soldering these days is lead-free anyway) was of minimal concern, esp. given the use of fume extractors and air filtering. Bigger issue was dust lead, that was handled by good hygiene practices (masks & gloves) - but that is not really a major concern in a typical small workshop/lab setting.https://www.academia.edu/download/36285781/vol1no2271204.pdfhttps://www.tandfonline.com/doi/abs/10.1080/10807039.2020.1730690The problem are mostly flux fumes which are irritant and can lead to asthma - and then various plastic fumes (e.g. melting wire insulation) that inevitably occur when assembling and reworking boards.