Airbrushing and dust contamination

[michael080]

good morning,

I am living close to Stuttgart in Germany and everybody who has been there knows that it is located in a deep valey. It has always been a town with a lot of air pollution problems. Years ago the town administration set up local measurement stations to determine the air quality. The values were so concerning that traffic was restricted in some days in winter times. People were concerned and started to wonder what impact that would have on their living in the town. To gather more information, a group started to develop cheap measurement devices that could be setup for some 30€ and that allowed to analyse the airborne particle load in the 2.5µm and 5µm size range. This project is still very active and I have build a couple of these devices in the last years. If you want to see how the results look, visit

https://maps.sensor.community

Yesterday eveneing, I painted some parts from my BR70 project while one of these sensors was sitting on my bench for testing.

here is what the particle counter detected.



The background load of these counters is at about 5µg/m³ for the smaller 2.5µm particles and peaks up to almost 300µg/m³ immediately.
The EU limit for this size of dust is 50µg\m³. 2.5µm particles are respirable!
It opened the windows right after spraying, so the values come down again quite quickly, but this is a large 25 sqm room under the roof wiht a high ceiling and it was a small paint job.

I am using a fume extraction cabinet that are sold at ebay cheaply and I am using a simple FP3 mask while spraying, but this is a worrying result.

My conclusion is that I will use my tightly sitting Draeger respiratory mask with P3 filters from now on even for spray jobs using acrylic paint.

On the positive side, good to see that my air brush atomization is working very well.

Michael

 

[David Waite]

Dose your fume extraction unit expel the fumes outside via a flexible hose? If so do you have a window that is open on the opposite side of the room when using the extraction unit? this seems to be something the a lot of people don’t think of if you remove air from a room you must have a fresh air supply entering preferably somewhere opposite the extraction unit so the air flow across the room helps to keep the room air clear.
David.

 

[Yorkshire Dave]

Dose your fume extraction unit expel the fumes outside via a flexible hose? If so do you have a window that is open on the opposite side of the room when using the extraction unit? this seems to be something the a lot of people don’t think of if you remove air from a room you must have a fresh air supply entering preferably somewhere opposite the extraction unit so the air flow across the room helps to keep the room air clear.

This makes sense as the extraction unit will effectively lower the air pressure in the room, which will in turn draw in the dust, particles and particulates with the natural high to low air pressure flow.

Ideally you would want a filtered air supply being pumped in at a higher rate than extraction to maintain a higher pressure as the air flow through an open window will drag in dust, etc as well as kick up any which is in the room.

In an ideal world the spraying room would always be at a higher air pressure than the surrounding atmosphere as the natural air flow from high to low pressure will also draw the dust, particles and particulates out in addition to the extraction unit.

Alas, we have to make the best of what we have unless we have one room effectively fitted out as a clinical laboratory for this purpose - which would make it an expensive luxury.

 

[michael080]

Dose your fume extraction unit expel the fumes outside via a flexible hose? If so do you have a window that is open on the opposite side of the room when using the extraction unit? this seems to be something the a lot of people don’t think of if you remove air from a room you must have a fresh air supply entering preferably somewhere opposite the extraction unit so the air flow across the room helps to keep the room air clear.
David.

Here's the situation:



The cabinet pushes the contaminated yair through the window. As you can see. the window is only slightly open tp allow the flat nozzle of the hose through the opening. I am aware that contaminated air might just be pulled back in through the window. So there is another window behind me taking the picture that is also open a bit to let some air into the room, however, I don't want to have too much air moevemnt, so not wide open. You may notice that the filter mats from the cabinet have been removed to increase air flow. Thie fan is one of the older 230VA/60W AC fans that have been replaced at more recnet cabinets with 30W DC fans.

@Dave, I thought that my workshop layout would be quite OK. The reason I wrote my initial report is that I was quite shocked that even a reasonable ventilation system may produce such a heavy contamination. You are right, clean rooms are always pressurized, but this is no option unfortunately.

Michael

Michael

 

[LarryG]

Back in time, I was spraying almost every day and on top of that I was working in a makeshift photographic darkroom after dark. Stop-bath and fixer plus cellulose started to play havoc with my body and mind within a very short time, yet I didn't make the connection with these chemicals at the time. This was around 1977. It wasn't until 1991 that I started to get a grip of the problems, as taking control of ones mind is not easy when it is telling us something different.

More recently, an eye test detected a piece of wood embedded in one eyeball which had skinned over. It was removed followed by a course of antibiotic eye application. I now have to wear spectacles permanently and take dry-eyes drops. I've bought eye protectors that clip over my specs to give side protection for when I'm sawing or filing wood.

We put ourselves in danger while modelling without realising it at times. In addition to glues, metal and wood filings, we can now add the various resins. Efficient ventilation plus eye and respiratory protection are absolutely paramount.

 

[Giles]

Replacement air is best served at high volume but low velocity - so it may be best to open a window in another room and have doors fully open for your supply, rather than a window cracked open in the room in which you are working. This will lift less dust generally as the air speed should have slowed right down.
There are now water-curtain booths available for spraying. We used to have a large one for props work which was good, but you can now get modelling sized ones. The large ones cut down over-spray better than a normal booth, we found.

 

[Tim Watson]

The other consideration at this time of year is drawing in pollen.

Tim

 

[John_B]

My airbrush and compressor have just arrived, and the spray booth should be here on Sunday, so this is something I'm thinking about at the moment. I think the airbrush will be sharing a smallish room with 2 x resin and 2 x filament 3D printers, and a diode laser, so extracting all the nasty stuff can be done in one place. I could put in ducting to draw air in from the opposite side of the house, away from the road to avoid traffic fumes. I may well take the glazing out of the smallest window pane, and put in a panel with all the extraction vents fitted to it!

I've been considering air quality monitoring, both for my health, and because I need to both heat and extract fumes from the resin printers, which seems an expensive thing to do at the same time. I've got a stock of Arduinos and other microcontrollers, so could knock up something that opens and closes vents, turns fans on and off etc. as needed. Does anyone have any suggestions for what sensors to use, or anything I could buy ready made?

I'd be interested to know more about the sensor @michael080 is using.

 

[simond]

I’m very happy that sensor 64838 is green…

 

[DavidB]

View attachment 215057

I don't wish to dampen anyone's enthusiasm, but several years ago I had one of these. Mick Bonwick, tutor at Missenden demonstrated their inefficiency, showing how the extractor was simply not man enough. You could see spray escaping in to the room around the hood. Mick refused to allow anyone who brought one to Missenden to use it at a Weekend, using one of his instead. I used to have one and ditched it.

For several years, Derek Russan (Eileen's) used to have them but even he realised they were not up to snuff and stopped selling them. Both examples were pre-Covid.

 

[mickoo]

Interesting, I bought one of these earlier in the year https://www.amazon.co.uk/gp/product/B09B1NVC8R/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&th=1 specifically to measure HVCO and TVOC from my resin printer (Saturn 2 with Sirayatech Fast Navy Grey resin), the results from that were interesting, an open printer with vat exposed did not trigger unsafe levels of HCHO or TVOC's. It put my mind at rest so I've not invested in any form of ventilation for my printers.

What did trigger the alarms was the IPA cleaning agent used to clean prints afterward, that sent the sensor lunatic but soon dissipated once windows opened, you only need open a container with IPA in and it'll trip the safe levels in under two minutes in an average sized family room.

What I haven't tried is particle levels when spraying and I'm quite poor at ventilating to be honest, unless I'm doing etch primer in which case the booth hose goes out of the window and I wear a mask.

Am I at risk? Yes, am I 100% safe? No but then I view the 10-15 minutes exposure 2-3 times a week as a low risk situation and quite frankly, I've worked in far more (unbeknown at the time) toxic places in my youth and to be blunt.

 

[mickoo]

I don't wish to dampen anyone's enthusiasm, but several years ago I had one of these. Mick Bonwick, tutor at Missenden demonstrated their inefficiency, showing how the extractor was simply not man enough. You could see spray escaping in to the room around the hood. Mick refused to allow anyone who brought one to Missenden to use it at a Weekend, using one of his instead. I used to have one and ditched it.

For several years, Derek Russan (Eileen's) used to have them but even he realised they were not up to snuff and stopped selling them. Both examples were pre-Covid.

That's a fair point, they do shift some of the pollutants and are better than nothing, but if you're doing a lot of spraying for extended periods then they may as well go right in the bin.

 

[DavidB]

. . . quite frankly, I've worked in far more (unbeknown at the time) toxic places in my youth and to be blunt.

When I was at school, open dishes of mercury were not uncommon and I recall rolling the stuff around in my hand. At college, we used to smoke kymograph drums (coating them with a layer of carbon) by burning benzene. I know there were other things we did which would send health and safety ballistic today. Better not mention any more in case I give youngsters ideas.

This most probably explains a lot of my shortcomings these days!!

 

[mickoo]

When I was at school, open dishes of mercury were not uncommon and I recall rolling the stuff around in my hand. At college, we used to smoke kymograph drums (coating them with a layer of carbon) by burning benzene. I know there were other things we did which would send health and safety ballistic today. Better not mention any more in case I give youngsters ideas.

This most probably explains a lot of my shortcomings these days!!

Mercury, yup been there and done that We used to collect it out of tilt switches at BT, scoop it up with a sheet of paper or prod it with your fingers into the jar.

For years I washed my tools and (frequently) hands in R12, really got the grime out of your skin, but then R12 is about the most toxic ozone depleting chemical going! I used to braze refrigeration pipework which had R22 in, the fumes from that are a form of mustard gas.

To test fire alarms we burnt telephone cable as the detectors were bespoke to that cable insulation, common sense in a telephone exchange; in one test I over did it and passed out, luckily falling onto a floor grill where fresh air was pumped in, it saved my life and I woke up in the back of an ambulance on oxygen going to A&E. My incident provoked a national inquest where it was found that the fumes were highly carcinogenic and the type of cable changed for testing.

And those are the things I knew about, let alone the hundreds of hidden exposures I may never know about until it's too late. I understand peoples concerns and we shouldn't take risks if we can avoid it and I endorse all those that do take precautions; although sometimes I think it's a bit over the top personally.

Frankly the risks we know about are not dangerous, we can avoid or accommodate them, it's the ones we don't know about that should really scare us.

Having said all that, my closest call was from campylobacter (great for weight loss....2 stone in ten days) from uncooked chicken at an Indian restaurant....go figure.

 

[michael080]

I'd be interested to know more about the sensor @michael080 is using.

check this site: Build your own particulate matter sensor.

Easy and cheap to build and still quite reliable.

I don't wish to dampen anyone's enthusiasm, but several years ago I had one of these. Mick Bonwick, tutor at Missenden demonstrated their inefficiency, showing how the extractor was simply not man enough. You could see spray escaping in to the room around the hood.

I guess this is why I posted my observation. These things seem to be effective, but they are not at all!

I’m very happy that sensor 64838 is green…

Well, if the air isn't clean at the coast, humanity will be in trouble.
Take a look at Heathrows approach path and you can see that some people are not so lucky today. (20:57)

Michael

 

[John_B]

check this site: Build your own particulate matter sensor.

Easy and cheap to build and still quite reliable.

Thanks. Can they be used offline properly without connecting to the sensor network? I doubt if the interior of my small room will be of much interest to the rest of the world, and might cause panic to people who don't know I'm painting, 3D printing and laser cutting in there!

 

[John_B]

I don't wish to dampen anyone's enthusiasm, but several years ago I had one of these. Mick Bonwick, tutor at Missenden demonstrated their inefficiency, showing how the extractor was simply not man enough. You could see spray escaping in to the room around the hood. Mick refused to allow anyone who brought one to Missenden to use it at a Weekend, using one of his instead. I used to have one and ditched it.

I've got one arriving on Sunday! Are the latest ones any better? Would fitting a bigger fan, or more of them, help. What's the alternative?

 

[simond]

Well, if the air isn't clean at the coast, humanity will be in trouble.

Indeed. The sensor appears to be very close to the old lifeboat station in Hythe.

It’s an interesting location, with some very expensive coastal apartments, some older ex-council property, an industrial estate, an old sewage farm and a military small arms range all within sound, sight (and, I guess, smell) of one another!

I imagine if the ranges are in use, the particulates might be a bit more evident, short term.

The other thing that is very apparent on stormy days is the visible haze in the air along the shoreline, I suspect this is salt spray, which is particulate (but water soluble and hygroscopic), of course. I wonder how the sensors react/cope. It certainly plays havoc with any metalwork in the area.

 

[Lancastrian]

Take a look at Heathrows approach path and you can see that some people are not so lucky today. (20:57)

Michael

It's ok though because Citizen Khan has his ULEZ!

 

[mickoo]

I did a quick test today for 2.5µm particles whilst spraying.

Base level was already high at 37 in the workshop and outside is also quite poor at 24, possibly due to the sea mist (the coast is 4.5 Km away), low wind levels and living 120 m meters from the arterial road to the countries biggest container port, mind, today is the weekend so truck traffic is about 10% of normal weekday levels.

I fitted a clean filter to the unit and slung the hose out of the window, it has no end so is a direct tube right through to reduce back pressure, I didn't open any doors to get a flow of clean air.

The meter was placed just to one side of the booth (500 mm) furthest from the window, so worst case scenario really; ideally you need it on/near your chest to measure what you're taking in, I might try that next time.

Spraying Tamiya fine primer and the count hovered between 47 and 53 for ten minutes, changed to Halfords acrylic satin black and sprayed that for two minutes, the count peaked at 119; both were mixed 50/50 with cellulose thinners.

It's not perfect and there is room for improvement, but as a base test I can live with the moderate levels for short duration's.