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Description:

KIWOCOL 31 is a high viscosity diazo-emulsion with very high solids content for thick emulsion coating and very coarse mesh counts. It is used for printing solder paste, ceramic inks, resistors and other applications where high ink lay down is required. KIWOCOL 31 is solvent resistant and slightly water-resistant. It offers excellent copying qualities on all mesh counts.

Sensitize with Sensitizer #2 (supplied). Allow the mixed emulsion to settle after sensitizing to allow air bubbles to escape. Keep the emulsion in a cool (68°F / 20°C) and dark place during that time. (See sensitizer label for instructions).

To achieve a good stencil, the mesh must be degreased with a commercial degreaser such as KIWO Degreaser 1:20 or PREGAN A9 and must be free of dirt, dust, ink residues and ghost images. Rinse the screen thoroughly using low water pressure to remove any degreaser remaining on the screen. A foaming degreaser such as KIWO DEGREASER 1:20 or PREGAN A9 helps to determine proper and complete rinsing. See KIWO DEGREASER 1:20 or PREGAN A9 technical data sheets for details.

KIWOCOL 31 has excellent coating properties on mesh counts of 40-305 threads per inch ( 16-120 threads per cm). For best printing results, the following coating techniques are recommneded using a round edge coating trough:

40-86 tpi (16-34 tpcm): 1-1 wet-on-wet
110-156 tpi (40-60 tpcm): 2-2 wet-on-wet
145-305 tpi (77-120 tpcm): 2-3 wet-on-wet

Always start with 1 or 2 coats on the substrate side of the screen to fill the mesh openings; then finish with wet-on-wet coats on the squeegee side to build up the emulsion coating to the desired thickenss. The correct coating technique for your process must be determined through coating tests.

Contact KIWO for more specific coating techniques.

Dry the screen in complete darkness, or under safelight conditions, with the screen in horizontal position with the substrate side down. Temperature, relative humidity and airflow affect the drying time. The screen must be dried thoroughly before exposing to achieve highest resistance to ink and ink cleaners. A temperature of 86°-104°F (30°-4°C) at a relative humidity of 30% -50% and moderate airflow are optimum conditions. Drying at room temperature and in uncontrolled conditions may lead to inconsistent results and varying screen resistance.

Expose with ultra-violet light at a wavelength of 350 – 420 nm. A metal halide lamp provides the best results. Due to the many variables that determine the actual exposure time, accurate exposure times cannot be given. The following example is offered as a guide only:

Lamp: 5000 Watt metal halide at 40" (1m) distance.

156/62 tpi (60/62) yellow mesh, coating technique 2-2.
Exposure time: approximately 200 seconds.

The correct exposure time for your equipment and mesh selection, must be determined through exposure tests using a step exposure or and exposure calculator such as the KIWO STEP WEDGE EXPOSURE film or the KIWO EXPOSURE CALCULATOR films.

Under-exposed screens feel slimy on the squeegee side during developing. At correct exposure time, the screen is not slimy. Overexposure leads to loss of detail. Correctly exposed screens will withstand high tap water pressure during washout.

Contact KIWO if you have further questions regarding exposure time.

Develop the screen using full tap water and a medium spray pattern. Adjust the water temperature to lukewarm or slightly colder. Rinse thoroughly from both sides of the screen. Vacuum off any excess water or blot it off with newsprint paper. This will avoid runs or scum from under-exposure in the open areas.

Post-exposing the screen after developing and drying is not very effective. To improve the resistance by 15% the post-exposure time needs to be 6-10 times the original exposure time. Instead of gaining resistance from post-exposure, expose the screen fully with the initial exposure.

The emulsion can be chemically post-hardened using HARDENER AWR or HARDENER HP to improve water resistance. HARDENER HP improves the resistance, but the emulsion remains reclaimable. HARDENER AWR results in a permanent stencil with outstanding resistance. See HARDENER AWR or HARDENER HP Technical Data Sheets for details.

When printing with solvent based inks, retouching, blocking out can be done with KIWO TOUCH-UP and KIWO BLOCKOUT. See KIWO TOUCH-UP, KIWO BLOCKOUT Technical Data Sheets for details.

KIWOCOL 31 can be decoated with emulsion removers such as KIWO STENCIL REMOVER. Before decoating, ensure the screen is completely cleaned of ink or ink cleaning chemical residues. If water beads up on the stencil, degrease the screen prior to decoating. See the KIWO STENCIL REMOVER Technical Data Sheet for details. If the screen was chemically hardened with HARDENER AWR, reclaiming is no longer possible.

When under-exposed, the emulsion can cause emulsion haze after reclaiming. To remove haze, use KIWO HAZE REMOVER or PREGAN PASTE. Use the haze removing products with the KIWO INK WASH and haze remover activator or KIWO ULTIMATE INK WASH. These products are also very effective at removing ink haze. See separate Technical Data Sheets for these additional products for more details.

Viscosity : approx.: 24,000 mPas
Viscosity sensitized: approx.: 10,000 mPas
Solids Content: approx.: 37%
Color: violet
Color Sensitized: violet
Storage: 1 year at 68°F/20°C
Potlife: 4-6 weeks at 68°F/20°C
Precoated screens: 1-3 weeks in complete darkness at 68°F/20°C
Freezing: protect against freezing
VOC: none
TLV: n/a
HMIS rating: Health – 1
Flammability – 0
Reactivity – 0

1 Quart, 1 US Gallon, 5 US Gallons, 55 US Gallon Drum.

For additional product information, please visit www.kiwo.com or call PCS at (919) 266-4463.

Thank you for choosing KIWO.

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