When producing sandblasting templates with RAYZIST Photomask films, the details are decisive. Based on our many years of experience, we have written answers to the most common technical questions for you. This guide will help you choose the right thickness of UV film and handle the exposure, washing and sandblasting itself flawlessly.
1. Introduction and selection of the appropriate RAYZIST UV film
What are RAYZIST UV photoresist films and what are they used for?
These are professional materials that allow you to transfer even very fine graphic details to the sandblasting mask.
- They have a wide range of uses. They are ideal for sandblasting glass, metal, stone (including granite), ceramics, wood or plastic.
- They allow you to achieve high resolution and detail that is unattainable with a conventional cutting plotter, including halftones of “shaded photos”.
- We offer the SR3000 series, which is self-adhesive and removable “positionable”. Furthermore, when establishing long-term cooperation, it is possible to supply the SR2000 version, which requires the application of glue and thus gains super adhesive ability even on matte surfaces.
What UV film thickness (mil) should I choose for my project?
The choice of UV film thickness depends on the fineness of the motif and the desired sandblasting depth.
- 3 mil (76 μm) SR3000: The most versatile choice for fine details, halftones and common sandblasting of glass, crystal or polished metals. We still have this version in stock in the Czech Republic.
- 4 mil (102 μm) SR3000: Suitable for medium-detail graphics and fonts, it allows slightly deeper sandblasting on any surface. We deliver this version when establishing a long-term cooperation. It is not in stock in the Czech Republic. The estimated delivery time is 14 days.
- 5 mil (127 μm) SR3000: Ideal for coarser motifs, deep sandblasting (e.g. wine bottles) or stepped sandblasting. We still have this version in stock in the Czech Republic.
- 6 mil (152 μm) SR2000: Sandblasting stencils made of this UV film are suitable for very deep sandblasting of hard materials. We deliver this version when establishing a long-term cooperation. It is not in stock in the Czech Republic. The estimated delivery time is 14 days.
- 9 mil (229 μm) SR2000: This is a very durable sandblasting UV film for sandblasting fonts and motifs on monuments and other very hard materials. We deliver this version when establishing a long-term cooperation. It is not in stock in the Czech Republic. The estimated delivery time is 14 days.
What is the difference between SR3000 and SR2000 UV films?
SR3000:
- Classic washout, self-adhesive, UV pohotoresist films, which we supply in two different thicknesses. The sandblasting stencils made of these UV films are removable and can be used for detailed sandblasting of various glossy materials. For sandblasting matte surfaces, a special Rz-2 adhesive, which we also supply, can be applied to increase adhesion.
SR2000:
- This type of UV pohotoresist film is not self-adhesive. After drying the sandblasting template and before its subsequent application, it is necessary to apply Rz -2 glue, which we also supply. After applying the glue, it becomes a highly adhesive sandblasting template and can also be used on unpolished stone.
2. Exposure of UV foil and preparation of graphics for printing an exposure template
What graphic materials and applications do I need to prepare an exposure template?
Common vector programs such as CorelDRAW, Adobe Illustrator or Inkscape are suitable for creating themes.
- Vector graphics: Use black and white vectors for common signage and logos. The rule is black = sandblasted.
- Halftones: To sandblast photos, you need to convert the image to a raster (e.g. in Corel using the Jarvis or Halftone method with a circular dot).
- Printing an exposure template (matrix): Print the graphics on a special inkjet or “laserjet” laser foil. For optimal results, print in CMYK mode with 100% black (K) settings.
Do I have to work with UV film in complete darkness?
No, UV films are not extremely sensitive to ordinary room light.
- Safe lighting is regular fluorescent (incandescent) lighting, in which you can handle the UV film for approximately 1-10 minutes.
- Beware of UV radiation! It is necessary to avoid direct and indirect sunlight (open windows or doors), which illuminate the UV film in a few seconds.
How to properly expose UV film?
The UV film is exposure through a printed transparent exposure foil (matrix) in the UV exposure unit.
- Place the UV film with the glossy side down on a table. Place the printed foil on its matte (emulsion) side (the side with the print black color directly on the UV film).
- For a Letralite UV exposure unit (15-25 W), the recommended exposure time is 20 seconds. Times may vary depending on the age and power of the source.
3. Washing and drying sandblasting masks
How does the process of washing out of a sandblasting mask work?
Unexposed areas of the UV film (covered with black paint on the exposure foil (matrix)) are washed with pressurized water, creating a pass-through sandblasting template (the details are held together by micro layer, which is removed and sandblasted by sandblasting.
- For washing, use a washout pad, to which you attach the UV film, for example, with a magnet, and for washing, use a pressure gun with a flat nozzle.
- The water temperature should be between 15-40 °C (warmer water speeds up the process, but a maximum of 55 °C). Set the water pressure to 60–90 psi (4–6 bar).
- Spray from a distance of 5-10 cm in smooth up and down motions until the template is clean and transparent.
Is there a time limit for washing out?
Yes, the process should not exceed 90 seconds.
- With prolonged washing, there is a risk of saturation of the UV film with water, which can lead to damage to fine details or shift of lines.
- If the UV film is not washed out quickly, it is probably inadvertently expose by UV light.
How to dry the stencil properly?
After washing, remove excess water (e.g. by blowing or shaking).
- At room temperature, dry the mask for 20-40 minutes.
- In the dryer at 50 °C, drying takes about 10-15 minutes.•
- A properly dried mask has a uniform color and is ready for application.
4. Application of the sandblasting mask and the sandblasting itself
How to apply a sandblasting stencil without bubbles?
The sandblasted object must be perfectly clean, degreased and dry before application.
- Place the sandblasting mask on the material with the matte side. The template is removable so you can repeatedly remove and move it until you’re happy with the placement.
- Use a plastic burnisher to squeeze the air from the center to the edges and press the mask firmly.
- Finally, remove the top transparent transfer layer.
- To loosen any microbubbles, we recommend using a special “bublex” wire roller.
What abrasive (sand) and pressure should I choose for sandblasting?
We recommend using high-quality corundum (aluminum oxide) or silicon carbide.
Grain size according to the thickness of the UV film:
- 76 μm (3 mil): F220 grit
- 102 μm (4 mil): F180 grit
- 127 μm (5 mil): F150 grit
Working pressure:
- For pressure sandblasting, we recommend a pressure of 2-3 bar.
- For an injector (suction) system, the pressure should not exceed 5,5 bar.
What to do if sandblasting mask don't stick after drying?
In dry or cold environments, the mask may temporarily lose its optimal stickiness. However, it can be easily restored with moderate moisture.
- Just gently “inhale” the matte side of the mask with your mouth,
- or place it on a damp, lint-free cloth for a while.
Once the stickiness is restored, you can apply the mask immediately.
What is the easiest way to remove a sandblasting mask after sandblasting?
There are several simple and quick ways.
- Peeling: The sandblasting mask can be simply peeled off by hand after the work is done, leaving no adhesive residue on the surface.
- Soaking: soak the sandblasted object in warm water for 3-10 minutes, then the mask will begin to release on its own.
- With pressurized water: You can also effectively wash the mask off the item with a high-pressure cleaner.
