Thick Stencils with Image Mate PC 701

 

1. In a UV light protected area, select the proper screen for producing a thick stencil. The mesh should have good tension for uniform stencil thickness. For best results, use a dry screen that has been cleaned with Image Mate Degreaser 260.

 

2. Fill a sharp edge scoop coater at lease ¾ full. Refill coater as needed. Although a round edge coater can be used, fewer coats may be needed and may change the estimated outcome below.

 

3. At a slow, consistent speed (~ 5 seconds to cover 12 inches) with constant pressure, apply 2 coats to the print side (outside) of the screen. Coating too quickly can create air pockets which may lead to pinholes. Print side coating only fills the mesh.

 

4. Flip the screen over and apply 2 or more coats on the squeegee side (inside).

** All coatings are applied wet–on-wet, do not dry between coats! **
TIP – when coating on the squeegee side, rotate the screen 180-degrees after every 2 to 3 coats and continue to coat the final 2 to 3 coats on the squeegee side.
TIP – You will not build up EOM if you continuously flip between print side and squeegee side – i.e., once you’ve coated the print side, do not recoat the print side.
CRITICAL - Always finish coating from the squeegee side. The emulsion must be pushed through the mesh onto the print side to form the stencil walls.

 

5. If you are attempting a high density stencil, keep an eye on the print side as you add coatings. If it begins to run, you’ve added too much emulsion.

 

6. Immediately after the screen has been coated, dry the screen in a dry, dark area. The screen must be racked horizontally with the print side down to keep the emulsion flat on the print side.

CRITICAL – Especially for HD stencils, aim a fan directly onto the screen, allowing air to circulate around the screen.

TIP – Place another “junk” screen underneath to catch any possible drips.

TIP – Use a dehumidifier to maintain less than 30% relative humidity.

 

7. Allow the screen to dry overnight or use a moisture meter to ensure complete dryness.

 

8. Expose properly.

TIP – Better results occur with positive images having greatest opacity. Vellum papers likely will not work. We recommend output from an image setter or Chromaline’s AccuArt inkjet films.

TIP – In humid conditions, the stencil may stick to the glass; use a sheet of acetate for easy removal.

NOTE – Exposure times must be increased with increasing stencil thickness.

 

9. Develop the stencil by submerging the screen in warm water for 5 to 10 minutes. Spray the print side until the image develops. Pressure washing should be done carefully from the print side only.

NOTE – Half-tones/fine lines should not be thinner than the stencil thickness.

 

10. Dry the stencil completely before printing. Post-exposure of the squeegee side may increase durability if the screen was originally underexposed.

 

Estimated drying times of freshly coated screens, based on the following ideal environmental conditions:

Temperature: 80~90 degrees F (27-32 C)

Relative humidity: less than 40%

Air movement: good air flow from fans

coating / mesh (tpi)	355	230	110	60
1 + 1	10 min.	20 min.	30 min.	45 min.
2 + 2	15 min.	25 min.	35 min.	60 min.
2 + 4	20 min.	30 min.	45 min.	80 min.
2 + 6	30 min.	40 min.	60 min.	100 min.

 

 

 

 

 

 

 

 

 

Estimated dry stencil thickness – typical results found by manually coating with sharp edge coater. Thickness measurements are emulsion over mesh (EOM). Your specific thickness may vary.

 

 

 

Estimated exposure times (Light Units) are based on the above dry stencil thickness chart, using the following:

Light source: metal halide (single bulb)

Power: 800 watts, with light integrator

Positive type: camera, thermal, or Chromaline’s AccuArt films

 

	355 tpi	230 tpi	110 tpi	60 tpi
1 + 1	5 LU	20 LU	30 LU	45 LU
2 + 2	15 LU	25 LU	45 LU	70 LU
2 + 4	25 LU	30 LU	90 LU	100 LU
2 + 6	30 LU	40 LU	115 LU	150 LU