MACDERMID AUTOTYPE PHOTOGRAVURE - ROTOGRAVURE G-35 GRAVURE PIGMENT PAPER DISCONTINUED.
In particular, G35 is designed to give a straight-line reproduction of middle and shadow tone densities thus giving improved tonal separation in this region. The properties of G35 make it an ideal product for computer controlled etching and off-set gravure conversion processes, as well as general commercial printing. The product is suitable for all climates.
G35 will produce a high contrast result with a diazo lamp (417 nm) for optimum screen exposure but shorter wavelength lamps will produce lower contrast and optimise results for tonal reproduction in the diffusion exposure stage of the conversion processes. Conventional tone exposures also require less exposure time than G25 type products. G35 is ideally suited to single bath etching and is resistant to premature rotting.
G35 Gravure Pigment Papers
WORKING INSTRUCTIONS & SAFE HANDLING (Unsensitised paper)
Store in a cool dry environment.
Wash hands after repeated use.
Use Yellow Safelights or Amber Filters. Sensitising is recommended in a 3% ‘pure’ potassium dichromate solution at 11 oC ± 1 o with a pH of range 5.3 - 5.5. The immersion time should be 3 minutes exactly. Squeegee onto a Plexiglass’ glazing sheet which is free form scratches and grease, remove all surplus dichromate. Dry the sheets at 20 - 22 oC/58 - 62% RH, allowing ca 90 minutes with even distribution of air. Store the dried sheets at 6% moisture content in sealed containers at -18 oC for long periods or +5 oC for overnight storage. Reconditioning of 4 hours is necessary in the former instance and 0.5 hours in the latter prior to opening the container.
Open in a light-safe room and allow to condition, positioning the sheets on Formefilm with appropriate registration holes. Expose emulsion side to a white line screen in a vacuum frame using a long wavelength UV lamp (417 nm). Further expose the emulsion side to the diapositive montage in a vacuum frame. This may involve either a long or short wavelength UV lamp, the latter being more common (365 nm). Measurements should be carried out to ensure the correct level of exposure. Details are given in Autotype Technical Bulletins.
Transfer the exposed sheet to a precleaned chemically prepared copper surface with a minimal quantity of water. The water must be pure at 20 - 22 oC, with a high pressure roller of ca 80 o IRH. The cylinder should rotate at 3 - 4 m/min and water should essentially be kept to a minimum.
Remove the stabilising film if used without plucking the paper and immerse the cylinder in alcohol (IMS 55 OP 80%) for at least 2 minutes. This should be followed by water at 45 oC with vigorous and even agitation until the paper is removed. Continue development for a t least 8 minutes, followed by cooling at 20 oC until cylinder temperature stabilises. Soak the resist in 80% industrial alcohol for 5 minutes, squeegee off and dry at ambient air temperature. Allow at least 2 hour conditioning at 21 oC ± 1 oC/60% ± 2% RH prior to etching. Stage areas not required for etching with Autolac. Etch the resist in a good qualityproprietary etchant to the required reproduction curve, ensuring even wetting and agitation of the etchant.
NOTE: Pigment papers are normally sensitised in a POTASSIUM DICHROMATE solution which is TOXIC. After sensitising the product acquires the toxicity of the sensitiser.
SHELF LIFE & STORAGE
WARRANTY EXPRESS OR IMPLIED other than that materials conform to their current applicable standard specification. Statements herein therefore should not be construed as guarantees of satisfactory quality or fitness for purpose. The responsibility of Autotype International Limited for claims arising out of breach of guarantee, negligence, strict liability or otherwise is limited to the purchase price of the material.
Suggestions concerning working practices and procedures are based on the practices adopted by existing users of the products and are made in good faith. IT IS THE RESPONSIBILITY OF THE USER TO ENSURE THAT ALL RELEVANT HEALTH AND SAFETY LAWS AND REGULATIONS ARE COMPLIED WITH. Autotype International Limited does not provide any advice on such laws and regulations and accepts no responsibility, express or implied, for breach of such regulations.
Statements concerning the use of products described herein should not be construed as recommending the infringement of any patent and no liability for infringement arising out of such use is assumed.