2. Degreasing Screen Printing Mesh

Mesh preparation is the easiest, cheapest and quickest way for screen printers to improve screen life. This useful How to Guide will show you the best way to maximize stencil adhesion to a mesh which will save you time and money by removing the need to remake screens that have broken down on the press.

The importance of mesh preparation

Polyester mesh is the most commonly used mesh today because it is resistant to most screen cleaning chemicals and it doesn’t absorb water or change tension during use. However, the down side is that untreated fibers of a Polyester mesh have a very smooth hydrophobic surface. Inks and solvents then deposit greasy ink residues to this surface, making it very difficult for a water based stencil or emulsion to adhere effectively!

The key to overcoming this problem is effective mesh preparation to help the stencil adhere better to the surface.

What should a prepared screen look like?

Luckily that's easy to see. A well prepared screen should be able to hold an even film of water as seen in the picture opposite, where the right hand side was prepared with Universal Mesh Prep. A quick and simple test can tell you straight away how well prepared your screens are - we've called it The Mesh Prep Challenge.

This is a simple 3 step test that will very quickly demonstrate just how well prepared your screens are today. 

  1. Prep half of your screen as usual

  2. Rinse it with a water spray

  3. Look at how much water it holds

Why not take a look at how well the Universal Mesh Prep handled the challenge, and compare it to the degreasing chemicals you’re using today.

Degreaser or mesh wetting agent?

Alkemi offers screen printers two types of degreaser

The Degreaser Concentrate range is diluted with water prior to use, so 1 liter of Concentrate can make up to 30-50 liters of degreaser solution.

The concentrates work brilliantly for Alkemi PLUS direct emulsions, however if you are using Capillex screen film, then we recommend Universal Mesh Prep, which is a combined degreaser and mesh wetting agent. This helps the mesh to hold as much water as possible which is the key to applying Capillex capillary film successfully.

Pro tip: to save time, always degrease the mesh after decoating the previous stencil and then store cover the screens during storage to prevent recontamination.

Stencil films

If you are using Capillex capillary film or an indirect stencil film such as Five Star, then it is important to abrade/roughen the mesh as well as degreasing it. This will ‘key’ the smooth mesh fibers allowing the stencil to adhere better. The picture opposite shows the level of micro-abrasion that ‘keys’ the surface without damaging the fibers

Top tip: Abrade all new screens and after every fifth stencil to get the best results.

Autoprep Gel

This ready to use micro-abrading liquid is simply applied to both sides of the wet screen with the Alkemi Brush for a perfect result. The Alkemi Brush has soft, chemically resistant fibers to give the maximum effect without damaging the mesh. Can be used with Auto Degreaser Concentrate solution, Universal Mesh Prep and Autoprep gel.

 
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