Mixing room · Guide
Start with the process, not the catalogue — equipment, ventilation and regulations in plain language.
Read this first. This guide offers general tips based on our experience. It does not take over your responsibility — you must always check for yourself what applies to your own operation: environment, legal requirements, fire and occupational-safety protection and local permits. If you are unsure, check with your local authority, the fire and rescue service and whoever is responsible for occupational health and safety.
A mixing room — the paint-mixing room in a refinishing workshop — is not a product you buy, but a workplace you build. This is a complete guide to planning it — equipment, ventilation and regulations seen together. Most people start with the catalogue and look for "a mixing cabinet". We think you should do the opposite — start with what is actually going to happen in the room. What are you mixing, how much, and how do we keep the air clean while you do it? Once you have that clear, almost everything else falls into place, and you get a mixing room that works, is safe to work in and lasts for many years.
Because the most important thing in a mixing room is not which cabinet looks the best. It is the air you breathe. When you weigh, mix and clean guns, solvent evaporates — and if you work with two-component paint, isocyanates are released. These are fumes you cannot always smell, and they are at their worst right where you are standing. So ventilation is the common thread running through this whole guide.
Click through the steps — and note that it is steps 2, 3 and 6 that are the critical ones from a health point of view. That is where the fumes come, and where the ventilation has to be.
The paint base, mixing cup and stirring stick are made ready.
The base paint and tinter (toner/pigment paste) are weighed out in the correct proportions according to the colour recipe on the scales.
Stir the paint to the right colour and viscosity.
The actual spraying takes place in the spray booth, outside the mixing room.
Into the waste container, if you have one.
Ventilated, and always one material type at a time — never waterborne and solventborne in the same cleaner.
Paint storage — Store or Tiro. Paint, thinner and hardener must be kept ventilated. If you have plenty of space, Store is a good choice — it gives the room a more open feel. If space is tight, take Tiro instead: a lot of paint in a small footprint, and because the shelves pull out you still see everything you have. Keep two things apart — a ventilated cabinet is not the same as a fire-rated one (more on that further down).
Digital scales and mixing machine. Both the scales and the mixing machine are usually part of your paint supplier's system, so you don't buy those from us — we work with all the major ones (Standox, Cromax, Spies Hecker, Glasurit, PPG, DeBeer and more). Just bear in mind that the scales need to stand firmly, free of vibration and at a comfortable working height, so plan for a solid base and run power to where the machine will stand.
Mixing bench — Mix or Midimix. The bench is the heart of the room. The Mix benches have ventilated base cabinets and a supply-air box at the front that gives you fresh air right where you work, handle isocyanates safely and are prepared for LED lighting. Midimix is clever if you have a window looking into the booth: it is low and open, so you can keep an eye on the booth while you mix.
Mind the hazardous-area classification (Zone 2). Midimix has no supply air, which makes the classified zone around the cabinet a little larger: Zone 2 normally extends 1.5 metres out from the cabinet, compared with 0.5 metres for a Mix cabinet with supply air. Make sure you have that clear space around the bench, and always check the zoning against the current area-classification plan for your mixing room.
Cleaning bench — Clean 100, Kombi or Systemtvätt. The guns must be cleaned ventilated and separately from mixing. Clean 100 is about right for smaller workshops and for those working alone with a single material. Kombi suits you if you prefer to wash by hand or already have a cleaner from, say, Drester. Systemtvätt 195 is made for when there are several painters and you run both waterborne and solventborne.
One rule that is never bent: never wash two different materials in the same cleaner. If you need to clean both solventborne and waterborne, use two separate units. We explain why in Never wash water and solvent in the same washer.
Spill and waste. A waste container for the leftover paint before cleaning belongs in the workflow (we don't sell that ourselves). Separate the waste into two labelled bins — hazardous in one, ordinary in the other. The bin for solvent-bearing waste must be ventilated, and you need an agreement with a company that collects hazardous waste, such as Renova or Stena.
Miljö cabinet for a solvent recycler. Roughly one workshop in three recycles its thinner in a solvent recycler. If you do, it must stand ventilated and on its own — the Miljö cabinet is built for exactly that, with a spill lip and room for supply and exhaust air.
Ventilation must be calculated, not guessed. The requirement for a ventilated cabinet is governed by the cabinet's open area — from the bench up to the top and across the opening — multiplied by how fast you want the air to be drawn in:
exhaust air (m³/h) ≈ open area (m²) × air velocity (m/s) × 3600
How fast the air needs to move depends on what you are doing. For mixing a gentler draught is enough, around 1.2 m/s. For cleaning you want more, around 1.5 m/s, because more evaporates then. That is the logic behind the figures in our product sheets.
There are then two ways to build the room. Either you run the cabinets as fume cupboards — in which case the exhaust-air figures in the brochure apply for each cabinet, and that is how it should be if the cabinets stand out in the open workshop (we strongly recommend the fume-cupboard approach then). Or you treat the whole mixing room as one ventilated area, in which case the cabinets mostly just need supporting ventilation.
A few rules of thumb that always apply: solvent fumes are heavier than air and sink, so the exhaust air should be taken low, down at floor level. It is a good idea to keep a slight negative pressure in the room so the fumes don't find their way out into the workshop. And make sure the supply air matches the exhaust air — otherwise the extraction is choked.
Reminder: general tips — always check what applies where you are.
Storage. For active storage indoors at the workplace, the guideline value is 50 litres per fire compartment without special separation. If you need to store more, fire separation or a fire-rated cabinet (SS-EN 14470-1) is required.
Permit. For professional operations indoors (non-public), the limit is 500 litres of flammable liquid. If you exceed it, you apply for a permit from the local authority. Add everything up — paint, thinner and hardener across the whole premises, not just in the mixing room.
Do the cabinets have to be EX-rated? No. A well-ventilated, passive cabinet usually does not — good ventilation shrinks or removes the explosive zone. More on why in Why Greenline cabinets are not EX-marked.
Do you work with 2K and isocyanates? Then it is about more than equipment: training renewed at least every five years, and medical checks with a certificate of fitness. The ventilation must be chosen and documented so that exposure is kept as low as possible.
A mixing room should serve you well for twenty years, not just until the next inspection. Tell us what your workshop looks like — number of painters, materials, space and ventilation — and we'll help you put the whole thing together.
