Have you ever wanted to create a 3D effect on a t-shirt and wondered how this is done using screen printing? The mystery of this will be no longer, as the following ‘How To Screen Print’ guide will show you how to make stencils for printing these amazing 3D effects.
Ultra thick stencils are often required in textile printing to help deposit a high ink layer for special effects such as 3D printing, High Density Printing or suede leather effects. The key to creating these ultra thick stencils is to first choose a high solids, one pot emulsion such as CPS Ultra Coat HB as this will give the maximum build, for the minimum numbers of coats. CPS Ultra Coat HB is also photographically fast as it is very important that these ultra thick stencils are fully exposed.
One of the biggest problems is how to coat a thick emulsion layer but prevent it from sagging when it is wet. The secret to success is to 'skin' the emulsion on the print side to hold the emulsion as the thickness is built up.
The emulsion is 'skinned' by blowing a cold air fan onto the surface of the print side immediately after coating. This dries just the surface layer to form a skin.
How To Coat High Build Emulsions By Hand
When coating manually it is very important that the screen is held firmly. A simple coating stand can help significantly. The screen should be held vertically, angled slightly away from the operator.
Depending on the size and shape of the coating trough it can be held either at the ends or by the body. Ensure that the trough is level and even pressure is applied across its length. Try to keep a constant coating angle for the coating trough lip. It is important that the trough does not ride over the edge of the frame or onto a high build adhesive overlay otherwise this will lead to thick edges.
It is important not to have the screen too high as this could affect the trough lip angle in the upper part of the screen. Typically the top of the screen should be no higher than your chest.
Ensure that there is no loose clothing (or hair) which could come into contact with the wet emulsion or that the screen is positioned too low for comfort.
A very coarse mesh is required, typically a 21/cm or 32/cm. This has a large open area to create the maximum 'well volume' for the ink. Stencils of up to 300 microns can be produced without the need for intermediate drying.
1. Use the more rounded edge of the coating trough for the base coats.
2. Use a dry, well degreased screen held firmly. Level the trough to prevent thick edges.
It can never be emphasised enough just how important thorough mesh preparation is. It should be looked upon as one of the basic ground rules when producing stencils.
Failure to pretreat mesh can lead to costly breakdown and screen re-coating in production, which can easily be avoided by taking these few extra and inexpensive minutes at the very beginning.
For more information on mesh preparation, take a look at How to Screen Print: Mesh Preparation for Emulsions.
3. Apply firm, even pressure and we use a slow coating speed to minimise air bubbles.
4. Apply a second coat from the print side.
5. Look for a glossy surface on the squeegee side. This shows the mesh has been filled with the emulsion. If coating looks patchy, apply a further coat from the print side.
6. Turn the screen around.
7. Turn on a cold air fan to blow air on to the print side. This fan will dry the surface of the emulsion to form a skin. Imediatly apply a coat on to the squeegee side.
The wet emulsion layer underneath can then be increased by applying additional wet coats to the squeegee side to create the ultra thick stencil.
To build up the stencil thickeness you can apply up to an additional 10 coats to the squeegee side without intermediate drying. However, make sure you rotate the screen by 180° after every additional two coats to prevent the thick layer of emulsion from running and sagging.
8. Dry the screen horizontally overnight at a temperature of 35°C.
9. Make sure it's fully exposed.
10. Washout the screen from the print side with a strong spray.
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Name: William Shorter
Mobile Number: +44 7831 109181