The FT COAT PRO is our popular one-component photo emulsion for textile and graphic printing for water-based screen printing inks. This environmentally friendly emulsion can also be used for printing with discharge inks. It is technically impressive across the board and has many properties that are otherwise not available on the market in this combination.
The emulsion is highly resistant to water and abrasion, making it perfect for printing large print runs. Thanks to the high edge definition and excellent mesh crossing, even fine motifs can be sharply exposed with this coating. With a solids content of 43%, the emulsion is relatively viscous and applies so well during coating that a high, sharply defined print shoulder is produced. FT COAT PRO delivers the best results on both white and yellow fabric and impresses with a very short exposure time.
The photo emulsion should be stored at room temperature between 10 °C and 30 °C. The container must be protected from frost and direct sunlight. The shelf life is 1.5 years. We recommend processing the photo emulsion under yellow light.
Several screens can also be coated in stock if they are then stored in a dark place. If required, they can then be exposed within 3 weeks. However, the screens must be dried again with warm air immediately before exposure. This is because photo emulsion has a tendency to attract moisture from the room air.
The screen printing frame to be coated should be dry and dust-free. It is therefore advisable to clean the screen frame with degreaser (e.g. our DEGREASER) before coating and then dry and store it as dust-free as possible until coating.
The emulsion is first poured into a suitable coating trough until it is about half full. Then coat first on the print side (outside, Fig. 1) of the screen and then on the squeegee side (inside, Fig. 2). If dark textiles are to be printed with the screen later, the print side can optionally be coated wet on wet twice in succession. This builds up a thicker emulsion layer on the screen mesh. A correspondingly higher ink application is therefore also achieved during subsequent printing.
A comfortable working position is recommended for coating, which allows the channel to be guided firmly and securely over the frame. If you do not have a coating stand, you should coat as shown in the photos.No master has yet fallen from the sky! Good coating is purely a matter of practice. The coating on the fabric should initially not be applied too gently, but with medium to high contact pressure. If the coating is applied with too little pressure, the worst case scenario is that too much emulsion is applied. The excess emulsion will then form lugs and drip off the screen. In practice, such thickly coated screens cannot be dried or exposed correctly. In this case, it is recommended that the screen be washed out and recoated. The aim is to apply a uniformly thin layer of emulsion.
Experience has shown that newcomers to screen printing in particular tend to apply too much emulsion rather than too little. Our urgent recommendation to beginners is therefore to coat each side of the screen exactly once with the sharp edge of the coating channel.
After coating, the emulsion from the coating channel is poured directly back into the container to prevent unnecessary drying. The emulsion channel should be cleaned directly with water after coating. This applies in particular to the edges.
If this data sheet is not enough guidance for you, we recommend our practice-orientated YouTube video on coating screen printing frames. There we also show how to prepare screens and how to dry the emulsion properly. Click here to watch the video.
After coating, the screen is dried horizontally with the print side (outside) facing downwards. This allows the emulsion to sink deep into the fabric and form a pronounced printing shoulder. The light-sensitive emulsion must be dried in the dark or under yellow light. At an elevated room temperature and a humidity of less than 50 %, drying takes place within 5 - 6 hours or overnight. However, sufficient air circulation should always be ensured.
Inadequately dried, moist emulsion is difficult to expose and, in the worst case, can lead to completely incorrect exposures. The emulsion then peels off in places or over large areas during development.
We therefore strongly recommend always drying the emulsion layer at around 40 °C with circulating air before exposing. As a rule, a drying time of 1 to 1.5 hours is sufficient. In professional operations, circulating air drying is carried out in a drying cabinet and in the semi-pro or DIY sector with a small fan heater.
If stock-coated, unexposed frames are dried and temporarily stored in cupboards, boxes or cartons for many days, they should definitely be dried again with circulating air at approx. 40 °C before exposure. This is the only way to ensure that the (residual) moisture, which is often barely perceptible, can evaporate from the supposedly dried layer. Remember: emulsion attracts water. In a damp environment (basement, cold workshop, bathroom), it tends to attract moisture from the room air.
Note for beginnersParticular attention must be paid to drying the emulsion. Only a completely dry emulsion can be exposed perfectly. A good 70 % of problems with subsequent exposure and even with decoating are due to incorrect or insufficient drying beforehand. We therefore recommend always using aids such as fan heaters with a blower function for complete drying. These only cost a few euros and can be purchased at any DIY store or supermarket.
ExposureThe frame with the well-dried and evenly applied FT COAT PRO emulsion can be exposed with all commercially available exposure units. The exposure time varies slightly depending on the exposure unit used, the layer thickness of the emulsion and the distance of the exposure lamp to the screen.
In the semi-pro and DIY sector, compact exposure units such as our exposure lamp UV LED 10 W (article number: BL0001) are generally used for exposure. Alternatively 400 watt halogen exposure units can also be used. With the usual 2/1 or 1/1 coating and a distance between screen and lamp of approx. 50 cm, the following exposure times result:
| tissue colour | Exposure time with exposure lamp UV LED 10 W | Exposure time with exposure lamp Halogen 400 W | Exposure time with UV LED- vacuum exposure table |
|---|---|---|---|
| White | 2:40 to 3:00 minutes | 4 to 5 minutes | 0:25 minutes |
| Yellow | 3:30 to 4:00 minutes | 5 to 6 minutes | 0:35 minutes |
A practical video guide to semi-pro exposure can be found in Part 4 - Exposing photo emulsion | Screen printing yourself of our comprehensive screen printing guide
The exposure time is usually considerably shorter with the standard UV vacuum exposure tables or the newer LED exposure units. With the FT COAT PRO, it is often between 20 and 30 seconds. The ideal exposure time can be easily determined here using a strip exposure test or an exposure calculator (article number: KALKU1).
After exposure, the motif is washed out directly. To do this, first apply water to both sides of the screen stencil without applying pressure. The stencil should then soak untouched for about a minute under yellow light or very weak artificial light. The motif should already settle slightly and become easily recognisable. After the soaking time, you can start to rinse the motif from the print side using higher water pressure. Finally, the screen is rinsed again intensively with a soft jet of water to rinse out the last emulsion residues (sludge) that are difficult to see with the naked eye. The emulsion should now feel firm and no longer greasy. If the layer still feels slimy or if pieces of the stencil come off unintentionally and in shreds, then the exposure time was insufficient or it is very likely that the emulsion was not completely dry before the exposure. If the motif is almost impossible or very difficult to rinse out, the exposure film was too translucent, the exposure time was too long or the rinsing was done in daylight or strong artificial light.
Once the screen has been successfully developed and dried again, it is essential to post-expose before the first colour is applied to the screen. The finished frame with the desired motif is therefore placed under the exposure unit once again and post-exposed for 3 to 4 times as long as it was previously exposed - without the exposure film, of course. This post-curing makes the screens very resistant to abrasion, harsh cleaning agents and, above all, the water in the screen printing inks. In addition, a well post-cured emulsion can later be decoated much more easily and even without a high-pressure cleaner. Practical tip: If the weather permits, post-curing can also be carried out in direct sunlight. However, daylight alone is not enough!
Decoating can be carried out with our ULTRSTRIP or ULTRASTIP25 concentrate decoater. First remove all colour residues from the screen, especially from the edges of the motif. We recommend using a suitable screen cleaner such as WASHOUT-AQ for water-based colours. Spray the ready-to-use decoater generously onto both sides of the screen, leave to work for 3 to 4 minutes and then rinse out of the fabric under high pressure (ideally with a high-pressure cleaner). If you do not have a high-pressure cleaner, you can also help with a decoating sponge. In practice, it is usual to degrease the frame immediately after stripping, allow it to dry and store it dust-free for the next coating.
If stubborn emulsion residues cannot be removed despite correct decoating application, this is due to insufficient drying of the emulsion before exposure. Failure to post-expose can also lead to decoating problems. In this video, we have summarised how to avoid problems during decoating and what measures can be taken to remove the emulsion residue anyway.
If the exposure doesn't work straight away, there are simple causes that can easily be solved. The most common problems for beginners have to do with too thick a coating, incorrect drying of the emulsion or arbitrarily set exposure times. We have produced a troubleshooting YouTube video to help you solve these typical beginner errors: Solving problems when coating / exposing emulsion
Problem not included? Then we will be happy to help you find the cause. For a precise analysis, it is very helpful if we receive a few informative, high-resolution photos of the problem at info@siebdruck-versand.de. We are also happy to advise you by telephone on 0391 / 243 587 53.
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