Airbrushing - overspray

[Adrian Harris]

I'm not this has been covered but what do people do about airbrushing models in the house.

I always avoided doing it in the house as Margaret had a general hatred of solvent/paint type smells, but that limits when painting can be done, due to temperature and/or humidity levels from the weather depending on the time of year.

Over the last couple of weeks I've rearranged the box room, to give myself a model table as well as an electronics table, and would like to get back into 1/35th models as well as AT ones.

Do people use the turntable & extractor systems which seem to be available, which seem OK for 1/48th and 1/35th models but too limiting for most AT parts. Would I need to erect some form of back cloth to catch the over spray if painting AT model parts, or does airbrushing use such small paint levels that over spray isn't a factor ?

Adrian.

[Steen Vøler]

Hi Adrian
Well, When I airbrush I do it in a small room in the house and keep the window open when airbrushing. When I am finished for that day, I normally power on a large fan to get the room proper ventialized.

When using spray cans, I always paint outside and have to wait for the weather to play along for this to be a succes.

All of this because I do not have a garage or shed

[Adrian Harris]

Thanks Steen. Do you get any over spray from the airbrush

> All of this because I do not have a garage or shed

A man without a shed to call his own That's so sad



Adrian

[Stephen White]

Adrian, good morning.

First, some stuff on general airbrushing:

http://www.armortek.co.uk/Forum3b/viewt ... =34&t=5786

I use the airbrush for everything except priming. With a selection of needle and nozzle sizes, you can cover from the most detailed 1/35th (0.2mm needle) through most Armortek parts (0.4mm) to covering sub-assemblies and whole models (0.6mm). Harder and Steenbeck do a deal on multiple needles). I only use rattle cans for etch priming. The airbrush is much more controllable and that minimises overspray. You can also minimise overspray by reducing the pressure and coincidentally increasing the thinning of the paint.

Before anything else, get a good mask. I recommend the 3M one:

https://www.arco.co.uk/products/126002? ... =undefined

You'd need to add the combination gas and particulate filters:

https://www.arco.co.uk/products/114700?s=1


With the control available with an airbrush, I don't find overspray a problem at all. I do tend to mask bits I don't want covered but it really isn't that necessary. You do need some form of air filtering and extraction though, not so much for the spraying itself but to clear the air for when you remove your mask.

It's not easy to sort the cheap rubbish from the over-expensive professional stuff. Look for a minimum extraction of 5mc/min or a fan of more than 30W. Also look for one to which its easy to fit an extractor hose (for feeding the output outside) and for which replacement filters are easily obtainable. I can recommend the bigger Aircom system:

https://www.everythingairbrush.com/resp ... e-38w.html

This system is particularly good for Armortek use because you can buy add-on modules to extend the size. I think two would be more than enough for a whole tank hull.

https://www.everythingairbrush.com/resp ... e-38w.html

You can easily get the fittings and hose to route the filtered air out of a window:

I also fitted a cheap strip light:

Hope that helps. Airbrush is definitely the way to go if you're serious about model painting.

Stephen

[John Caboche]

I don't use extraction when I airbrush, as I exclusively use acrylics and these don't cause bad odours at all. The quantities that they are used in for painting models are not harmful to health either. Even Armortek models.

If you are using solvent based paints or enamels you will need some form of extraction, especially with solvent based paints.

You shouldn't really need a mask either with acrylics - to be honest nearly all masks are a waste of time and money - they need to be face fitted to be effective and need to be right grade/protection factor for the airborne contaminant.

Any form of facial hair or stubble will drastically reduce the effectiveness of the mask enormously (one days growth of stubble reduces the effectiveness by over 90%).

Just my musings based on my experience

ATB John

[Stephen White]

Please disregard John's comments above. Any form of particulate aerosol is harmful if ingested in sufficient quantity. The recommendation is emphatically to use a mask when airbrushing and an extraction system is desirable. Facial hair does not reduce the effectiveness of a mask by "over 90%". That is a complete misappreciation of the way in which such filter masks work (see the UK Health and Safety Executive Guidance). British Army respirators, for example, are designed to remain effective with facial hair.

It is true that most acrylics carry a label advertising the paint as "Non-toxic". That refers to the absence of chemicals regarded as harmful if ingested. That does not mean, however, that an aerosol of the product is harmless. Far from it. Note that most acrylic paints contain advice such as "Use in a well ventilated area. Avoid contact with eye, skin and mouth" (Tamiya). Acrylics are preferable to enamels when airbrushing. For that reason, the Knowledge Base recommends using acrylics for basecoats and oils and pigments for weathering.

The best official advice is widely available and pretty consistent in advising the use of protection when airbrushing. For example, the US Office of Environmental Health and Safety recommendation is as follows:

Airbrush, Spray Cans, and Spray Guns

Artists use many products in spray form, including fixatives, retouching sprays, paint sprays, varnishes, and adhesive sprays. Airbrush, aerosol spray can and spray guns are used.

Hazards
1.Spray mists are particularly hazardous because they are easily inhaled. If the paint being sprayed contains solvents, then you can be inhaling liquid droplets of the solvents. In addition the pigments are also easily inhaled, creating a much more dangerous situation than applying paint by brush.
2.Aerosol spray paints have an additional hazard besides pigments and solvents. They contain propellants, usually isobutanes and propane, which are extremely flammable and have been the cause of many fires. Other aerosol spray products such as retouching sprays, spray varnishes, etc. also contain solvents, propellants and particulates being sprayed.
3.Airbrushing produces a fine mist which is a serious inhalation hazard because artists work so close to their art work. Airbrushing solvent-containing paints is especially dangerous.
4.Spray guns are less common in art painting but usually involve spraying much larger quantities of paint than either spray cans or airbrush. Spraying solvent-based paints is a serious fire hazard.

Precautions
1.See section above for precautions with pigments.
2.Try to brush items rather than spraying if possible.
3.Use water-based airbrushing paints and inks rather than solvent-based paints.
4.Use spray cans or an airbrush in a spray booth if possible.
5.If ventilation is not adequate, then respiratory protection is necessary while air brushing or spraying. Contact EHS for selection and fit-testing.
6.Never try to spray paint by blowing air from your mouth through a tube. This can lead to accidental ingestion of the paint.


I've put this strongly as my own advice but if necessary will repeat it in the Knowledge Base.

Stephen

[Stephen White]

My apologies. I've just noticed in my first reply to Adrian that I omitted the crucial ("and particulate") to the combination filters recommended for the 3M mask. These contain both a gas filter and replaceable particulate filters. I've edited the post accordingly. Stephen

[Adrian Harris]

Thanks for the advice. I invested in some of these 3M masks when spraying the Mk IV parts in the summer:

https://www.arco.co.uk/products/117400?s=1

When spraying with rattle cans or wiping down with Upol System 20 or acetone, there was never a whiff of chemical through them, and the addition of replaceable filter covers meant that they lasted much longer. I did stick to the "replace after 28 days" recommendation, even though I wasn't using it every day. Not probably necessary but with the increasing number of cases of COPD, one can't be too careful.

Will look to invest in an extraction system once I get the work room back in one piece. The lesson for today lesson is how to lay carpet

Adrian.

[John Caboche]

You are of course free to disregard my advice however I will point out that I know quite a lot about health and safety and I am reasonably experienced at it. I hold a degree equivalent qualification in occupational safety and health (NEBOSH Diploma part 1 and 2) and a post graduate diploma in regulatory health and safety. My day job is as an HM Inspector of Health and Safety with the Health and Safety Executive and I have worked in the health and safety field for about twenty years and for HSE since 2009.

I have an awful lot of the guidance Stephen has cited in hard copy on the shelf above my desk and quite a lot of other publications such as the catchiley titled “Hunter’s Diseases of Occupations” also on the shelves and I have quite a good working knowledge occupational health issues.

I am more than aware of the hazards and risks associated with spraying of paint and aerosolised paint in atmosphere. I believe in realistic risk management as does HSE as an organisation, this means not over reacting to minor risks and managing real risk with the necessary control measures.

The first issue I’ll address in reply to Stephen is the paint. As I said I spray exclusively acrylic paint through my airbrushes. I do a lot of model making.

True acrylic paints such as Vallejo Model Air, Ammo of Mig Jimenez and Citadel Air are acrylic polymer emulsion paints. The actual mix of polymers varies by manufacturer but is usually based around Poly (methyl methacrylate) (PMMA). The emulsion means it's suspended in a solvent (water); the acrylic polymer (plastic) is the binder, and the pigment gives it the colour. These paints are water based and no toxic.

The polymer mix binds to itself, the pigment and to the surface which is what forms the plastic layer as the water solvent evaporates.
All “toy standard” acrylic paints conform to ASTM D-4236: (ASTM 4236: Standard Practice for Labelling Art Materials for Chronic Health Hazards – the standard required to sell art materials in the US where the above manufacturers sell) which means they have to list any ingredients that are chronically toxic. They do specifically say their paints are non-toxic and they are, otherwise they couldn’t sell them as “toys” as they do.

Tamiya Paint which is marketed as an acrylic actually isn’t an acrylic, it’s a form of lacquer. It is based around iso propyl alcohol (IPA). It has flammable warnings, irritant warnings, and instructions to use in a well-ventilated area. This does indicate the use of IPA as a solvent. These paints are well known for needing thinning with IPA or Tamiya X20A thinner rather than plain water (which makes it gooey). Gunze modelling paints are similar in make-up and composition to Tamiya paints.

The next point Stephen raises is “facial hair” – in my defence I have a full beard myself so this is a subject close to my heart.

The book you need to refer to is:

Respiratory protective equipment at work – A practical guide - HSG53 (Fourth edition, published 2013) ISBN 978 0 7176 6454 2
I would specifically refer you paragraph 82 – page 23

“The wearer needs to be clean-shaven around the face seal to achieve an effective fit when using tight-fitting facepieces. Training is a good opportunity to make employees aware of this. If workers have beards, or are unable to be clean-shaven, a tight-fitting device will not be suitable so an appropriate loose-fitting device should be chosen”.

Paragraphs 71 and 72 – page 19 – underpin this

“If you are considering RPE with a tight-fitting facepiece, you should make sure that each wearer undergoes a fit test. Remember, people come in different shapes and sizes, so facial differences will mean that one kind of RPE is unlikely to fit all. The differences are even more significant between men, women, and people of different ethnicity. If the RPE does not fit, it will not protect the wearer”

“Facepiece fit testing is a method of checking that a tight-fitting facepiece matches the wearer’s facial features and seals adequately to their face. It will also help to identify unsuitable facepieces that should not be used. Remember that tight-fitting RPE will only provide effective protection if the wearer is clean shaven, so they should also be clean shaven when fit tested”

A “loose fitting device” (respirator) is a powered positive pressure device that relies on a constant inflow of air to provide a positive pressure inside the face piece and thus prevent the ingress of airborne contaminant. This is the type of device I use in my shed when doing a bit of wood turning. It is also the kind of equipment I also use when I enter live asbestos enclosures to undertake inspections as a NAP (nominated asbestos person) for the HSE.

The actual advice from HSE contradicts Stephen’s assertion that facial hair and face fit are not factors when they plainly are.

There has been a lot of research done on this:

HSL’s own research report (RR1052 Research Report - The effect of wearer stubble on the protection given by Filtering Facepieces Class 3 (FFP3) and Half Masks) quotes a lot of other research such as
:
Skretvedt O T and Loschiavo J G (1984) Effect of Facial Hair on the faceseal of Negative-Pressure Respirators Am. Ind. Hyg. Assoc. J45 (1:63-66 (1984)

“Bearded subjects consistently failed the qualitative fit test protocol”
An average two hundred and forty-six (246) fold drop in protection was experienced by bearded employees. (with half mask respirators)
At least a three hundred and thirty (330) fold drop in protection was experienced by bearded employees. (with full mask respirators)
Results indicate that the presence of a beard greatly increases the leakage through the respirator face seal, and this leakage should not be permitted when employees are required to wear respirators"


I have mistyped my percentage drop (90%) for which I apologise – it should be up to 9% - HSL’s research report states:

“The statistical analysis showed that by the seventh day, the predicted inward leakage may reach an unacceptable level (greater than 1%) for all of the facepieces tested. For some facepieces this occurred sooner”

Even a 1% drop in the efficiency of the RPE is not acceptable as far as HSE is concerned.

This research supports my assertion that poorly fitting respiratory protective equipment is not really worth having…

I can’t speak about the efficiency of British Army Respirators – I’ve never worn one – however if I were relying on one to protect me against chemical weapons I think I’d like a good face seal…

Airborne liquids in the form of fine sprays and mists and solid materials, including dusts, fibres, smoke and fume, require a particle filter. Each RPE type and class is categorised by an assigned protection factor (APF). The APF is a number rating that indicates how much protection that RPE is capable of providing. For example, RPE with an APF of 10 will reduce the wearer’s exposure by at least a factor of 10 if used properly, or, to put it another way, the wearer will only breathe in one-tenth or less of the amount of substance present in the air. The APF will need to be calculated on the basis of the workplace exposure limit of the substance you wish to protect against.

You can find this out from HSE’s EH40 document available from the website www.HSE.gov.uk

The grades of protection generally available for particulate filters/disposable masks are FFP1, FFP2 and FFP3 with APFs of 4, 10 and 20 respectively. If you want to use one you should purchase an FFP3 which are the highest grade and get it face fitted and be clean shaven.

In the case of Tamiya paints (I struggle to call them acrylics) Propan-2-ol (Iso Propyl Alcohol CAS 67-63-0) has workplace exposure limits of 400ppm/999mg m3 short term exposure limit (STEL – 15 minutes) and 500ppm/1250mg m3 long term exposure limit (LTEL – 8 hours) – this is very high and is based on industrial usage of the substance – not spray painting a model.

To get the level of airborne contamination over the WEL would take a lot of spray painting with an airbrush.

If you do want to invest in RPE then make sure it is of the correct standard and face fitted to you otherwise you are basically wasting your money. It’s your money however though so feel free to purchase what you like with it.

I would suggest based on my knowledge and experience that for time limited model spraying with acrylic paints you will not encounter too many problems with the inhalation of acrylic paint aerosols.

If you are going to use organic solvent based paints such as Alclad you will need to take precautions – a good bench extractor will provide the required protection, you should regularly test your bench extractor with smoke tubes (https://www.a1-cbiss.com/gas-detection/ ... tubes.html ). This will give an indicator of whether the bench extractor is working efficiently or not and whether there are any dead spots in the extractor hood.

Commercial Local Exhaust Ventilation (LEV) systems are required to be thoroughly examined and tested every fourteen months, this is in accordance with the Control of Substances Hazardous to Health (COSHH) Regulations – however I am making a presumption that the bench top systems being discussed are not being used commercially so COSHH doesn’t apply. In this instance I would suggest that regular filter changes and tests with smoke tubes would be sufficient.

If your bench top extractor is working correctly you shouldn’t need a mask, and if you’re not face fitted and clean shaven they’re not actually worth having for the reasons I’ve stated above.

If you want to find out more about LEVs I recommend HSE publication: Controlling airborne contaminants at work – A guide to local exhaust ventilation (LEV) (HSG 258) Third edition, published 2017 ISBN 978 0 7176 6613 3 which will tell you an awful lot about how these systems work.

All the best

John

[Stephen White]

John, thanks for posting such a comprehensive reply. Your expertise is evident. You have the experience and the patience to assess risks and discriminate. There lies the problem. Is it reasonable to expect a model maker to master all the relevant manuals, warnings and data sheets in order to arrive at a decision to use protective equipement? Probably not.

For advice to be useful, it needs to be both credible and simple to apply. If none of the chemicals we use posed any threat, it might be acceptable to advise against using protective equipment. That is not the case. in order to reduce the risks to "as low as is reasonably possible", protective equipment is a sensible choice.

It is of course a personal decision. If I were to elaborate in the Knowledge Base, I would unequivocally recommend masks and extractors. As it is, my comments above reflect my personal approach, not Armortek policy.

Finally, in the spirit of Christmas cheer, I offer the advice I was once given, that for men, facial hair is almost always a mistake, unless you're a sailor or a farrier. As a wise Guards Sergeant Major once said "you need to stand closer to the razor Gentlemen".

Stephen

[Christoffer Ahlfors]

Interesting!
I always use the disposable kind, since I only do spray work very occasionally. I was thinking along the idea of the assigned protection factor (APF, wow I learned something there!), that any mask would reduce the particles inhaled. Is this wrong for spray paint particles?

Cheers,
/Chris

[Simon Peck]

Oh dear. I thought model making was supposed to be fun?

[John Caboche]

Hi Stephen,

Thanks for the reply - In my time lurking around the forum and having met some members in person, I have formed the opinion (HSE Inspector speak... sorry ) that it is populated by two types of people - very smart ones and extremely smart ones - it's the reason that I don't like "blanket" approaches to health and safety - I prefer to give people the facts and let them formulate their own responses to risk control. I think overall that if this approach were adopted more often we would not be beset my many of the "elf and safety" stories we come across in the media and people may manage real risk in better way and avoid some of the unpleasantness I have encountered in my job.

My view is that overspray from airbrushing acrylic paint is of minimal (if any) risk - and that if you wish to mitigate any remaining risk, the risk control measures should be used correctly or they are no use at all... Just my thoughts - nothing more - people are still free to ignore me, we live in a free country.

Completely different to paints using organic solvents (such as toluene - nasty stuff) as a binder though

As an ex merchant navy chief navigator though I feel confident I would come under you definition of "sailor" and thus I am happy that my beard is both bushy and justified (and more importantly liked by my wife... )

@ Christoffer - any mask will reduce some particulate - if the mask fits poorly or is the wrong protection factor the research indicates that it will not reduce the particulate very much, if the risk is acrylic paint only I wouldn't bother (and I stress the "I"). If you are spraying anything else a good extractor (as pictured in Stephen's post) should take care of the risk and you shouldn't need a mask.

@ Simon, modelling is fun, I'm off to paint some space marines - lots of fun and I'll be using the airbrush I'll be pushing them around a wargames board making "pew pew" noises later, also great fun

[Simon Peck]

Hi John,

Enjoy your wargames. I appreciate your informative posts. I’m one of those who’d rather know the risks and formulate my own response to them.

Have a great Christmas,

Simon