Varnish and laminates for printing
Smith, Tony
1985-10-01 00:00:00
October 1985 PIGMENT AND RESIN TECHNOLOGY 7 Dr Tony Smith To oversimplify the issue it could be said that work has received to o much tack and stored in large laminates provide glossier surfaces than varnished stacks, then after a time sweating in the pile can ones, are relatively trouble free, but tend t o add 50% produce a solid mass. Consequently for high-tack to the cost. As in any oversimplification there are applications small stacks are important. There can degrees of truth, and certainly from the printers' also be problems with varnished surfaces when viewpoint , considerable skill and care is required in the y are folded. In general terms, more care is using both materials. required for gloss than for matt finishes. Varnishes Laminates Varnishing has traditionally been used mainly when Laminates are finding an increasing market for either a surface or part of a surface is required to brochure applications where a high gloss plastic- have a glossy type or in-depth surface. Among the type surface is required. There is no rub reaction or decorative varnishes Ultragloss UV is an acrylic any fingerprint marks associated with varnished varnis h with an extremely good surface for surfaces. They also tend to have a greater shelf life. enhancing cartons, books and general print, and has Typical laminated surfaces for journals are about 12 the ability to accept areas of foil blocking with flat microns thick, but for heavy brochured and map dies. Catalyt is a heat curing varnish suitable for work, they can be produced up to about 60 microns magazine covers, but it cannot be surface glued. fo r thick PVC applications. If a stiffening effect is HG2 is a genera l purpose nitrocellulose varnish wit h required the 15 micro n thickness is used. goo d abrasion and scuff resistance. Another Protection is given against general handling, nitrocellulos e varnish is Calender, due to the grease, dirt, water, weather and time depending process after application of passing the paper upon the laminates used. Orientated polypropylene throug h highly polished rollers. There are also matt offers good gloss wit h excellent tear resistance and nitrocellulose and silk UV varnishes. flexing strength. The orientation aspect of this term The type of varnish used depends partly upon the is concerned with treatment to enable the material surface to be printable. Acetate gloss is suitable for particular printing operation and also the drying techniqu e that is to be used. The two drying application s where improved foil blocking is techniques often used are air drying and the infra required. It has particularly good grease resistant red (IR) process which completes the operation in properties. OPVC (glossy) has extra ease for foil several minutes. Obviously the IR process is more blockin g and OPP (19) gloss has extra tear resistance. For a totall y matt finish, acetate (matt) is expensive because machinery is used, but the time saving in many instances is crucial. suitable. For food contact applications Polythene (DFL) has been developed. For die stamping in particular, a much higher quality of varnish is used fo r air drying than fo r IR. A t Ther e tends to be fewer problems in the on e company I visited, the Richardson Die production of laminated surfaces, although if the Stampinhg (RDS) No 8 was used for air drying and material has not been woun d correctly there can be RDS No. 4 fo r infra-red drying. creases and the final surface produced is not flat. Another factor determining the quality of varnish Scratches can also appear if pulling occurs. used is the actual thickness of gloss required. It is foun d that for heavy gloss applications a high Acknowledgement s quality varnish is needed. Also for heavy gloss Celloglass of Reading RG20DQ application s the l-R techniques of drying is Braithwaites of Wolverhampto n WV13Q6 preferable t o air drying, although considerable care Cotswold Laminates of Stow-in-the-Wold. has t o be taken that there is no 'sweat back' fro m the varnish throug h the paper to produce marks. Bexphane P. (Biaxially oriented polypropylene film) Varnishin g is not often used in letterpress Properties methods these days, but it has its applications in lithoprinting, particularly for sealing the printing. Nominal density Approximate Nominal Water-based varnish penetrates the paper sealing thickness g/m 2 yield reel length the required sections and presents a glossy image (microns) m2/kg m to the part required, using dampers. On drying, the varnish is not evident. 12.5 11.5 86.6 4000 High gloss or matt varnishes are among those 15.0 13.5 73.5 3400 available and the determination of the viscosity for 19.0 2700 17.3 57.6 particular operations takes considerable skill and 25.5 2000 23.1 43.4 experience. Too much tack can be a problem and 30.0 27.0 36.5 1700 this is controlled by the application of white spirit. Even after printing there can be problems. If the Acknowledgement: Hercules Powder Co. Ltd.
http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.pngPigment & Resin TechnologyEmerald Publishinghttp://www.deepdyve.com/lp/emerald-publishing/varnish-and-laminates-for-printing-NAQy0QUrId
October 1985 PIGMENT AND RESIN TECHNOLOGY 7 Dr Tony Smith To oversimplify the issue it could be said that work has received to o much tack and stored in large laminates provide glossier surfaces than varnished stacks, then after a time sweating in the pile can ones, are relatively trouble free, but tend t o add 50% produce a solid mass. Consequently for high-tack to the cost. As in any oversimplification there are applications small stacks are important. There can degrees of truth, and certainly from the printers' also be problems with varnished surfaces when viewpoint , considerable skill and care is required in the y are folded. In general terms, more care is using both materials. required for gloss than for matt finishes. Varnishes Laminates Varnishing has traditionally been used mainly when Laminates are finding an increasing market for either a surface or part of a surface is required to brochure applications where a high gloss plastic- have a glossy type or in-depth surface. Among the type surface is required. There is no rub reaction or decorative varnishes Ultragloss UV is an acrylic any fingerprint marks associated with varnished varnis h with an extremely good surface for surfaces. They also tend to have a greater shelf life. enhancing cartons, books and general print, and has Typical laminated surfaces for journals are about 12 the ability to accept areas of foil blocking with flat microns thick, but for heavy brochured and map dies. Catalyt is a heat curing varnish suitable for work, they can be produced up to about 60 microns magazine covers, but it cannot be surface glued. fo r thick PVC applications. If a stiffening effect is HG2 is a genera l purpose nitrocellulose varnish wit h required the 15 micro n thickness is used. goo d abrasion and scuff resistance. Another Protection is given against general handling, nitrocellulos e varnish is Calender, due to the grease, dirt, water, weather and time depending process after application of passing the paper upon the laminates used. Orientated polypropylene throug h highly polished rollers. There are also matt offers good gloss wit h excellent tear resistance and nitrocellulose and silk UV varnishes. flexing strength. The orientation aspect of this term The type of varnish used depends partly upon the is concerned with treatment to enable the material surface to be printable. Acetate gloss is suitable for particular printing operation and also the drying techniqu e that is to be used. The two drying application s where improved foil blocking is techniques often used are air drying and the infra required. It has particularly good grease resistant red (IR) process which completes the operation in properties. OPVC (glossy) has extra ease for foil several minutes. Obviously the IR process is more blockin g and OPP (19) gloss has extra tear resistance. For a totall y matt finish, acetate (matt) is expensive because machinery is used, but the time saving in many instances is crucial. suitable. For food contact applications Polythene (DFL) has been developed. For die stamping in particular, a much higher quality of varnish is used fo r air drying than fo r IR. A t Ther e tends to be fewer problems in the on e company I visited, the Richardson Die production of laminated surfaces, although if the Stampinhg (RDS) No 8 was used for air drying and material has not been woun d correctly there can be RDS No. 4 fo r infra-red drying. creases and the final surface produced is not flat. Another factor determining the quality of varnish Scratches can also appear if pulling occurs. used is the actual thickness of gloss required. It is foun d that for heavy gloss applications a high Acknowledgement s quality varnish is needed. Also for heavy gloss Celloglass of Reading RG20DQ application s the l-R techniques of drying is Braithwaites of Wolverhampto n WV13Q6 preferable t o air drying, although considerable care Cotswold Laminates of Stow-in-the-Wold. has t o be taken that there is no 'sweat back' fro m the varnish throug h the paper to produce marks. Bexphane P. (Biaxially oriented polypropylene film) Varnishin g is not often used in letterpress Properties methods these days, but it has its applications in lithoprinting, particularly for sealing the printing. Nominal density Approximate Nominal Water-based varnish penetrates the paper sealing thickness g/m 2 yield reel length the required sections and presents a glossy image (microns) m2/kg m to the part required, using dampers. On drying, the varnish is not evident. 12.5 11.5 86.6 4000 High gloss or matt varnishes are among those 15.0 13.5 73.5 3400 available and the determination of the viscosity for 19.0 2700 17.3 57.6 particular operations takes considerable skill and 25.5 2000 23.1 43.4 experience. Too much tack can be a problem and 30.0 27.0 36.5 1700 this is controlled by the application of white spirit. Even after printing there can be problems. If the Acknowledgement: Hercules Powder Co. Ltd.
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