The first thing to say is that for the standard spraybooth there are two types of filtration; air extraction and air input. Air extraction filtration means filtering the air as it leaves your booth therefore removing the paint, varnish, glue, dust or other airborne particles before it leaves your booth. Air input filtration is removing particulates before they enter your booth thus giving you a clean spray room.
We will start with the extraction booth filters as they are used within all types of spray booth. There are a number of different types of filter; cardboard concertina filter, multi-layer paper roll and fibreglass rolls. Each type of filter has its good points and not so good points, so the filter should, to a degree, be matched to your spray booth, its environment and the type of spraying you are doing.
Cardboard Concertina Filter - This type of spray booth filter is, now, the most commonly used. It should be fitted vertically within the booth and is constructed from two layers of different graded cardboard. The cardboard is folded in such a way that, when fitted, gives a filtration hole facing forward with a 'V' shape fold behind and a second, offset, filtration hole on the back. The air enters the front face of the filter, spins around in the 'V' and exits via the second hole. This spinning allows the airborne particles to be in contact with the second layer of cardboard (which has a higher absorbency level than the front layer) onto which they will adhere. You can see this process in more detail.
Multi-Layer Paper - Progressively built layers of absorbent paper that hold the paint particles and allow the air to pass throu`gh. The weave on each layer gets progressively tighter as you progress from the front layer to the last layer. This allows the air to continue through layers whilst they slowly catch and fill with overspray. This type of booth filter is best fitted horizontally. This type of spray booth filter is supplied in roll form and is still quite new to the market, but it is, as it should, be gaining popularity especially against the fibreglass filter.
- Procart K - Choice of 6 or 8 layer filter paper
- Procart KH - Choice of 5 or 7 layer plus additional fibre backing
Fibreglass - This type of booth filter has been around for many, many years. As with the Multi-Layer Paper it is progressively built and is best fitted horizontally. Where it differs is that the fibres aren't absorbent so the paint holding capacity is much lower than both above and especially against Multi-Layer Paper. Another drawback with this type of filter is that the fibres are unpleasant to handle and are very dusty. Having said this, the filter is very handy when there is moisture present or when unusual spaces need to be filled with some type of filter.
- Profibre - 50mm thickness fibreglass booth filter
- Profibre - 100mm thickness fibreglass booth filter
- Propora - 50mm thickness fibreglass booth filter for water-based paints
There is then a fourth type of spray booth extraction filter and that is Panel Filters. These are normally used for filtering the air entering a spray booth however with some types of booth set-up panel filters can be an option. You will see more information on panel filters below.
Air input filters are, normally, either a synthetic fibre or panel filters:
Synthetic Fibre - These are normally supplied in a roll or as pads cut to a size. They can be installed either vertically or horizontally and are available in a range of filtration grades depending upon the type of booth and the airflow available.
Panel Filters - Two main types of panel filter are available, either pleated or glass fibre. They can be installed either vertically or horizontally and come in a range of sizes and depths to suit your requirements. Pleated panels provide superior filtration levels and thus are the preferred panel for input filtration however the glass fibre panels are an option when your booth may suffer from low airflow so struggle if the pleated panels are fitted.