Industrial Chemicals

Under the Direct Emulsion Technique of stencil preparation Bluecoat is coated into the screens and within no time screen is ready for printing and this replaces the traditional time consuming and irritating methods of preparing the screens. Our Bluecoat PHOTO EMULSION which is one the textile adhesive manufactured under standard conditions and under strict quality control.

1. Cleaning the Screen

   Proper fabric treatment and adequate degreasing are very important for good result. Therefore, wash the screen with clean water and dry it.

2. Mixing

   Take 1 kg of Bluecoat emulsion in a clean vessel. Also take a glass of distilled water sufficient to mix 5 to 7 grams of Ammonium Bicromate and stir the solution till it is completely dissolved. Mix this solution of Ammonium Bicromate with the Bluecoat solution of 1 kg. and stir until the colour of the solution is changed to light uniform green. Viscosity of the emulsion can be adjusted with distilled water Filter the emulsion with bolting cloth and close the container at least for 1/2 hour so that all the air-bubbles are disappeared.

3. Processing and Coating Techniques

   It is always desirable that light in the Photography department is subdued light and if possible, yellow light.
   
   Direct emulsion coating requires skill to produce uniform pinhole free stencils. Important factors are the fabric mesh number, thread diameter, colour of the fabric the tension and the solid contents, the thickness of the coating blade, angle and speed of the coating blade across the screens etc. If you change the supplier of the bolting cloth, check and see that you are receiving the same type of material as before. Thus it is very important that print quality is dependent upon the correct coating technique. If the coating is made to the satisfaction then one coating is sufficient from outside otherwise repeat the procedure.

4. Drying

   After the coating is over, it is important to thoroughly dry the coated screen before it is exposed otherwise stencil quality will be poor. Moisture remain present in the coated screen even when the screen feels dry to touch if you are coating the screen for second time. It is important that the first coat be thoroughly dry before the second coat is applied. Dry the coated screens in horizontal position at room temperature with fans, to get best result and sharpness.

5. Exposure

   Exposing is one of the most important factors in achieving fine image and sharpness and maximum mechanical screen resistance. The only way of achieving the correct exposing is through adjusting exposing time using fixed factors such as no of tubelight, the quality of the light, set distance and set coating techniques and accordingly photography time is adjusted. Time of photography varies between 30 seconds to 120 seconds under standard conditions.

6. Washing

   Immediately after the exposure of screen wash the screen With gentle spray of water from the squeeze side i.e. inside until the image comes up if required use rubber foam gently.

7. Blocking out and touch up

   The most common method is to use the excess emulsion for filling the entire screen with a piece of cardboard it touching is required use the same material.

8. Drying with sensitizer

   After the screen is washed out. dry the screen and apply with piece of cloth liquid solution of ammonium bicromate. Before sending it to printing department, wash the screen with a sprayer to remove the excess bircromate. Your screen is ready for printing.

1. Time Saving
2. Long Runability
3. No Disruption
4. Sharpnes
5. Cleanliness
   

Take 1 Kg of Bluecoat 414 Emulsion in a clean vessel & also take 50 ml. of sensitizer. Mix them together for sometime till the colour of Emulsion is changed to light uniform green. Viscosity of the Emulsion can be changed by adding DISTILLED WATER depending upon mesh of the screen & technique of coating - i.e. machine coating or hand coating. Filter this emulsion with bolting cloth & close the vessel for 1 hour in cool dark place so that all the air bubbles are disappeared.

Degreasing & Cleaning the Screen

A completely grease free screen is required in order to achieve good fixing of Emulsion to the screen. Even if the screen is being used for the first time it is required to be degreased with the degreaser, by giving good rinse & immersion in degreaser & subsequent cleaning with pressure of water. Allow it to dry in a dust free area.

Coating of EmulsionDirect Emulsion Coating requires skill to produce uniform pinhole free coating. Bluecoat 414 Emulsion can be applied to a screen by using circular rubber squeegee. It should be verified that the rubber of the squeegee has constant & correct hardness, elasticity & diameter & even after prolonged use it maintains elasticity & it is not broken or cracked

Machine Coating
In this method Emulsion is applied automatically to screen in single action & one cycle of operation from top to bottom & it forms smooth adhesion between emulsion & screen so that practically no touching is required & pinholes hardly ever occur. Viscosity of the emulsion can be diluted by adding distilled water to suit the machine coating.

Hand Coating
In this type of technique round rings are inserted on both sides of rings & it is placed on floor in upright position & after that emulsion is applied to screen at even speed by using circular rubber squeegee from bottom to top at a even speed & put the screen in dryer. Depending upon the mesh of the screen additional 3 to 4 coats are required by repeating the above procedure.

After applying the emulsion the screen is transferred to dryer & dried by heating air approximately 30° C. & drying it to a relative humidity at 40%. In case of hand coating, if you are coating the screen for 2nd & 3rd time, it is important that the first coat be thoroughly dried before the subsequent coat is applied. Moisture remain present in coated screen even when the screen feels dry to touch.

Exposing the Screen

Exposing is one of the most important factors in achieving fine image & sharpness. The important aspect is deciding exposing time which depends on mesh of the screen, thickness of coating, light source for Photography & image pattern. Photo Emulsion is extremely sensitive to ultraviolet light & takes little time for photography. If exposing machines are fitted with metal halogenate lamps or xenon lamps then exposing time of 2 to 4 minutes are sufficient. Thus time of exposing varies from 2 minutes to 7 minutes depending upon light sources & exposure should himself determine time for photography.

An engraving is more than just the sum total of film screen & emulsion. Even if each of these product is individually of the highest quality, it is you-person on the job - who contributes the 100% to the ultimate quality of the engraved screen.

Keep the container closed & away from sunlight.

12 months, if container is properly closed.

10 kgs.