Paschke Online

Designs Ink Publishing Article Archive and Research Library

Chris A. Paschke, CPF GCF

 

 

"Thermographics"

May 1997

 

As we reach into the new millennium, technological advances continue to improve and expedite printing, photocopying, and photographic processes. These advances may indeed be making our businesses more efficient, but they are also creating a few headaches for framers. If we are surviving on a `need to know basis'...believe me we need to know as much as possible about all the things that might routinely walk through our front doors.

 

We are living in a disposable society. Felt pens were designed for ease and short term use, then we discovered as signatures they will fade from certificates. Thermographic tickets allow us immediate purchasing access to almost any event, but were made for admittance into today's event and not to be framed for long term posterity.

 

THERMOGRAPHIC PROCESSES

Thermographic is a term defining heat generated items, deriving from Greek "therme": heat; and "graphikos": of or relating to the art of printing...or, heat printing. Any process that uses heat or heat-sensitive paper will be effected by turning black if there is any application of heat during mounting. Sometimes the photos or copies are easily identifiable by sight or touch. Papers are smooth, slick, and shiny.

 

Thermographics were first noted as framing disasters with the onset of FAX machines when dry mounted copies were black when removed from the press, and has since spread to sporting events, cultural evenings at the theater, even airline travel. Heat- sensitive papers are everywhere.

 

Testing must always be done to verify an unknown if unsure concerning its origin. By gently touching the edge with the side of a warm tacking iron a heat-sensitized item will immediately turn black and still not damage the item.

 

INTERIOR ENVIRONMENT HEATING

Any application of heat, directly or indirectly; intentional or nonintentional, can activate the remainder of the paper to darken. Even the areas that have already been darken by their intentional activation through the original communication the lettering itself may begin to blend into the darkening background.

 

In other words, if a framed thermographic ticket is placed into a shadow box for constant viewing, and is allowed to heat up every day as the sun bakes the outside wall the artwork is displayed on, the ticket will continue to darken or disappear due to heat transfer alone. This is the natural activation of the thermal material the ticket is composed of by the environmental temperature within the frame heating up.

 

No special glazing, rag materials, or acrylic spray can prevent day to day warmth from aging it. If the ticket has potential dollar value as a collectible, it should not be framed at all. Only storing it in a cold place, such as refrigerator or freezer will delay the inevitable process of darkening. A potential solution to this dilemma would be to frame a duplicate, a 4-color copy perhaps.

 

FACSIMILES

Derived from the Latin fac simile "made like", fax refers to the process of reproducing graphic material at a

distance. The image is scanned by a light-sensitive device to produce an electric signal that is sent over telephone lines. Reproduction of the received copy can be photographic, electricity-sensitive, or thermal (heat-sensitive) paper.

 

Like the thermal paper tickets, thermal FAX paper has a slick feel to it with a slightly shiny appearance. If the FAX is not known to be printed on plain paper and doesn't have a toothed surface, it is probably a thermal paper and cold mounting methods should be employed. If the thermal paper is also very thin, then drier pressure-sensitives for mounting would be the best solution.

 

THERMOGRAPHIC PRINTING

In printing; thermography, meaning `heated printing', is a raised-letter printing process that simulates engraved

printing passed under a heater to fuse the ink and powder. Some inks contain an expansion agent when exposed to heat create a raised letter effect.

 

Inexpensive business cards, stationery and wedding invitations with raised plastic thermographic lettering will actually melt and flatten out into illegible blobs of ink if exposed to heat. Therefore cold mounting methods of wet, spray or pressure-sensitive applications are suggested.

 

THERMOGRAPHIC PHOTOCOPYING

In thermographic photocopying or `writing with heat', an original document and a sheet of special copy paper are passed together through a machine that exposes them to heat, or infrared rays. The ink used on the original must contain a metallic or carbon compound in order to absorb the infrared radiation. The copy paper contains a heat-sensitive substance fused between a transparent sheet of paper and a white, waxy backing. The original heats the darkened areas of print and transfers the image to the copy sheet.

 

THERMAL OR NON-IMPACT PRINTERS

Impact printers and dot matrix printers use an inked ribbon to pressure apply an image onto a sheet of plain paper. Non-impact printers require thermal or electrostatic transfers of the original image rather than by mechanical means.

 

Bubble-jet printers (aka ink-jet printers) squirt heated ink through a matrix of holes to duplicate the copy images. Laser printers form the image on a selenium-coated drum using laser light that transfers output from the drum to the paper. Thermal-wax-transfer printers and dye-sublimation printers use heat to transfer color pigment from ribbons to special papers.

 

Impact and dot matrix printers may be heat mounted. Any of the above mentioned nonimpact printers that utilize heat processes to transfer images from the original to the copy paper are heat-sensitive, and must be mounted using only cold methods.

 

PHOTOCOPIES

Heat and laminate tolerances of 4-color copies was the subject of the reported study in the last two-part series during March "Color Copies...Lightfastness to Laminates" and April "Color Copies...The Rest of the Story", PFM. Refer to them for additional information on dry mounting and suggested procedures when handling them.

 

The most common processes of photocopying uses an electrostatic technique to copy previously printed and pictorial material. Xerography is a dry method of printing that uses dry granular ink called toner. This is a copying process that uses static electricity or the attractive force of electric charges to transfer the image to a charged plate or drum.

 

Light reflecting off white areas of the image being copied erases the charge on the corresponding areas of the plate. Negatively charged powder toner is sprayed against the drum and sticks to the charged areas of the plate, creating a reverse image. The inked image is then transferred to paper and fixed by heat to create a permanent positive image copy.

 

Though electrostatic photocopying doesn't use thermal papers, it does use a heat-set ink process. As reported in the series above, it is therefore best to select a cold mounting techniques mounting is required. Keep in mind that wet and spray adhesives could contain too much moisture for thin copier paper stock to produce an unbuckled cold mounting, leaving pressure-sensitive the likely technique of choice.

 

COLD MOUNTING REVIEW

Any mounting technique requiring no heat or electricity, only adhesive and pressure to create the bond between an item and substrate is considered cold mounting. It generally refers to the use of pressure-sensitive adhesives. A thin sheet of adhesive film, or film with carrier, may be hand or machine applied.

 

Cold vacuum mounting uses a combination of adhesive and vacuum suction to create the bond. Wet, spray, and pressure-sensitive adhesives (or boards) all may be used with this process, and the bond is greatly improved.

 

MOUNTING FOR THE MILLENNIUM

There's more to thermographics than just a quick easy source for communication. Don't risk blackening the special business FAX or Super Bowl memorabilia by slapping it into a heat press simply because it appears to be on a regular piece of paper. The key is to really see what you are looking at and feel what you are touching.

 

Heat sensitive items come camouflaged and often masquerade as photograph look a-likes, theater tickets or memos. Though cold mounting is the viable option for many of these nonlimited edition mountings, preservation approaches will also always be applicable. But when affixing a potentially heat-sensitive project to a substrate is the mounting of choice, remember, if it can't stand the heat...cold mount.

END

Copyright 1997 Chris A Paschke

 

 

 

 

For more articles on mounting basics look under the mounting section in Articles by Subject.

Additional information on all types of mounting and creative applications in:

The Mounting and Laminating Handbook, Second Edition, 2002,

The Mounting And Laminating Handbook, Third Edition, 2008,

Creative Mounting, Wrapping and Laminating, 1999.

 

Chris Paschke, CPF GCF

Designs Ink

Tehachapi, CA 93561

P 661-821-2188

chris@designsinkart.com

http://www.designsinkart.com/library.htm