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COSHH Regulations For Handling 2K Paint Products

How to stay safe when handling two-pack paint

There are no two ways about it, paint shops are potentially very dangerous places. There is a wide range of different potential hazards that professionals in the finishing industries are exposed to on a daily basis.

From toxic chemicals through to serrations and burns, without proper safety precautions (and equipment) there would be a much higher incident rate in the finishing industries than we have today.

To ensure that professionals in the UK are protected as much as they possibly can be, the government Health and Safety Executive division has created a long list of regulations and advisory notices to help workers stay safe. In this article, we will be looking at the “Control Of Substances Hazardous to Health” regulations (aka COSHH) in relation to two-pack (2K) isocyanate paints.

While much of what is included in the governments COSHH documents amounts to common sense, there are numerous little pieces of reasonably obscure advice that are invaluable.

We would wager that most professionals in the finishing industries have not read these documents first hand. They are long, and quite frankly dreary reading that is usually way down on the list of priorities for the average worker.

However, this is a less than ideal situation, because despite being a boring read, they contain valuable information.

To enable you to digest the information in these COSHH documents (without having to spend your next 5 weekends reading) we have summarised some of the more helpful points in this article. We highly recommend you read the originals, but if you are unlikely to do that – this article will be better than nothing.

Most of the documents we will be discussing below specifically talk about the automotive industry. Despite this, this information is relevant for anyone working with 2K paint products such as professionals working on commercial vehicles, trailers, trains, caravans and other similar niches due to similar products being used.

This is serious stuff, we put this together as a guide only along with references to the official HSE documents. Call our knowledgeable team if you are at all unsure, we’re always pleased to help.

Mixing Two Pack Paint Containing Isocyanate – MR1

This glorious piece of writing might not have a catchy title (or even interesting content), but it’s an important read. We highly recommend you read the original MR1 safety sheet version in full. As you might have guessed from the inspired name of this document, it focuses on the dangers surrounding isocyanate two-pack products. It’s important for us to note here that this definition includes any products labelled as prepolymer, as it includes isocyanate.

What Are The Dangers?

Isocyanate is pretty nasty stuff, however, compared to some compounds found in paint shops it’s actually reasonably tame. It’s probably not going to kill you if you’re sensible with it, but its use does come with some serious risks. As such any two-pack paints that contain isocyanate need to be treated with respect.

One of the most common dangers associated with mixing paints containing isocyanate is related to inhalation. Something that needs to be cleared up right away is the potential carcinogen risk that is often shouted loud as a hard truth. The reality of the situation is that there is no evidence to suggest that inhalation of isocyanate from paints has ever caused cancer.

But that being said, other issues are present.

Breathing in mist created by paint containing isocyanate has been proven to cause asthma at alarming rates. Unlike many other airborne exposures, you do not need to breathe in isocyanate regularly (or substantially) to develop asthma. Even infrequent and short exposures can mean that you will need to carry an inhaler with you everywhere you go for the rest of your life.

While inhalation is the main cause for concern with paints containing isocyanate, there are also skin contact issues that need to be taken into account. If your skin is exposed to isocyanate then you are at risk of developing skin allergies and handling 2k paint ppe

What Precautions Do I Need To Take?

It is recommended that when mixing two-pack paint (or any paint for that matter) that it is done in a designated paint mixing room. This drastically limits the number of people that will potentially come into contact with the paint and makes the whole job much much safer.

Your paint mixing room needs to have good ventilation. This doesn’t have to be a fancy fan based extraction system, if you wish you can use natural ventilation from windows and doors. However, if you are using an extractor system, then ensure that the final extraction point outside is away from doors or windows (to prevent it re-entering the building).

If your paint mixing room is properly ventilated, you don’t actually need to wear respiratory protective equipment. Just make sure that all cans and bottles are properly closed after use to limit the amount of vapour that is built up in the room.

Skin protection is important, but again we are not talking about nuclear grade material here so the level of protection that is considered adequate is reasonably light. Single-use nitrile gloves are more than good enough for hand protection (and should always be worn when mixing). Don’t be tempted to reuse the gloves, throw them in the bin when you are done.

If your skin does come into contact with the paint, then there’s no need to panic. Simply wash the paint off as soon as possible with warm soapy water and rinse well.

Spraying Two-Pack Products In A Spray Booth Or Room – MR2

The sequel to the best selling guide above is the equally exciting MR2 document. This amazing piece of writing picks up where the MR1 novel we discussed above ended. It focuses on the safety of spraying two-pack paints.

What Are The Dangers?

The dangers outlined in this document are identical to the dangers we talked about in the section above (as it’s the same substance). Avoid skin contact, and don’t breathe it in without proper ventilation.

However, at the risk of stating the obvious, the environment and the manner that you are dealing with these substances differ drastically when you are spraying (instead of mixing). The isocyanate will be airborne during the spraying process which makes skin contact and inhalation much more likely.

What Precautions Do I Need To Take?

To deal with this additional risk that is posed by spraying 2K isocyanate-based paints we need to step up our safety game significantly. Failure to do most of the things listed in this section (or in the COSHH guide itself) will almost certainly result in some form of harm. There are several concerns we will cover here, they are not listed in order of importance.

The Spray Room or Spraybooth

The spray room itself is the first thing that needs to be taken into account. It is imperative to have the room operating at a very slight negative pressure to minimise the risk of particulate making it outside the booth. This should be checked daily.

Ventilation is super important and you should invest in an appropriate system that filters the air and disposes it (away from doors and windows) outside the building. When you have a proper ventilation system in place, it’s important to test the clearance time of the room.

Using a smoke machine, you are able to visually see how long it takes for the spray booth extractors to clean the air. Start a stopwatch and turn on the extractors, then wait until all the smoke is gone. This is the absolute minimum amount of time that should be allowed for before anyone enters the room without respiratory protection after spraying.

This test should be repeated often as over time efficiency can decrease. This increases the amount of time that needs to be allowed.

The Operator

Respiratory protection is the main cause for concern when it comes to the safety of the operator themselves. There will be large amounts of particulate flying around the room while it is in use – more than enough to cause harm in a single session.

Operators will always need to be provided with a tested and working constant flow airline system (E.g a mask or a hood). The reliability and quality of the air supply need to be checked very regularly, do this once a month at the absolute minimum (more frequently if possible).

Before any spraying begins the operator should check for damage. If damage is found spraying should not commence until an inspection/repair has been conducted. Airlines and respirators wear down reasonably quickly (especially the valves) so it’s a good idea to keep a bunch of spare parts in stock to limit disruption while maintaining safety.

Everyone in the spray room/booth needs to have proper respiratory protection, they should not remove their mask until they are safely out of the spray booth under any circumstances.

The operator should use single-use disposable overalls. These do not have to be replaced after every single spray job, but should be disposed of at the end of the operators workday. Again nitrile gloves are acceptable for hand protection, but unlike the overalls, these need to be thrown away at the end of the spray job.

Combine the overalls and gloves with a good air fed mask (with disposable visor protectors) and the operator is going to be able to safely go about their job with the minimum of disruption.

Cleaning 2K Spray Guns – MR3

The third part in our trilogy of gripping health and safety novels is probably the most interesting of them all. Once you have mixed your two-pack paint and safely sprayed it, you then have the task of cleaning all the equipment you have used. Read the MR3 cleaning 2k paint safety sheet.

On the danger scale cleaning your equipment after spraying isocyanate paint is much lower than spraying (but it’s more dangerous than mixing it).

The same potential hazards of asthma, skin allergies, and dermatitis are present – so we are going to skip that section and go straight on to the precautions you should take.

What Precautions Do I Need To Take?

Cleaning spray guns that are contaminated with isocyanate paints is probably the most commonly overlooked part of the safety process. It’s easy to see why, as it doesn’t really seem like there is any real danger at first glance. But when you are removing the paint from your equipment it becomes airborne again, which means you can inhale it and the same negative effects can manifest.

There are two ways to safely clean equipment that has been used to spray two-pack paints. The safest way is to use a dedicated sealed and extracted washing booth. These units are custom built for the job and allow operators to clean as aggressively as they want with almost no risk to their own personal safety.

Respirators are not needed while cleaning with a dedicated unit, and the sealed nature of the device means cleaning can be done almost anywhere (they are not portable).

If you don’t have a dedicated cleaning unit (they are not compulsory) then the cleanup process is a little trickier. Operators will need to be wearing full respiratory protection (like when spraying) and protective clothing will also need to be worn. The cleaning needs to take place in a dedicated room. It cannot be done in the mixing room, or even worse in the open workshop.

If you don’t have a dedicated room then the cleaning will need to be done in the spray booth to prevent wider contamination risking other workers. Again single use nitrile gloves will need to be used, coveralls are not required.

As you can imagine, cleaning this way is much more time consuming than using a dedicated gun cleaning booth.

SMART Spraying With Two-Pack Products Outdoors – MR5

While we have been reasonably sarcastic about the level of interest the other COSHH guides has provided us, this one is actually quite an interesting read. Read the MR5 safety sheet on SMART painting outdoors.

SMART spraying is regularly conducted outdoors. The dangers associated with two-pack paint are just as real outdoors as they are indoors. The problem is that the safety equipment used in the spray booth is not usually portable. So what do you do?

What Precautions Do I Need To Take?

The first thing that needs to happen when SMART spraying outdoors is that the work area needs to be cordoned off. There is a reasonable chance that some other people will want to be watching what you are doing, so ensure that the “no go zone” is enforced. This should be a minimum of 5 meters away from the spray site, however, 10 meters is the recommended size.

With this no-go zone in place the operator should be the only person that is at risk of coming into contact with hazardous levels of paint. The amount of paint in the air that can potentially be inhaled outdoors is reduced compared to an indoor spray booth (as it is able to float away). However, despite the amount of particulate being reduced, it is still well above acceptable levels and presents a danger. Respiratory protection is required.

Obviously, in an outdoor environment, the operator is not going to have access to the same line fed equipment that is available in the spray booth. For breathing, a portable supply of compressed air will need to be used. Before starting to spray you need to make sure that the air is fit to breathe, and that the operator has more than enough of it to finish the job.

Again, it’s very important that the equipment used is well maintained and is checked for any signs of damage before the operator starts spraying.

Apart from the nature of the air source being different, the actual safety requirements for outdoor spraying don’t really differ from spraying in a spray booth. So operators will still need a full mask, some disposable coveralls, disposable gloves, and ideally some tear away visor protectors.


So that concludes our reader’s digest version of the important HSE 2K painting regulations. However, despite it being a less than interesting read – we do still highly recommend you read each one if you can. What we have covered here is to be seen as a general overview only, there is much more important detail to be found in the official documents we have covered.

It’s interesting to note that the guidelines in these documents are not all legal requirements. Some of them are (which are noted in the documents) and these have to be followed for your organisation to be legal.

However, if you don’t want to spend days reading up on individual legal requirements to do the bare minimum, we suggest you just follow the recommendations in the guide. They are the safest way to work, and HSE state that if you follow the recommendations, you are nearly always going to be fully legal in your operations.

If you have any questions about anything in this article we highly recommend that you get in touch with our highly trained and dedicated sales team. They live and breathe this kind of stuff and would be more than happy to help you in any way they can. Why not give them a quick call on 023 8025 1100 for a no-pressure chat about your safety needs.

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