Thursday, January 12, 2012

Embossing: Part III

Stock Selection
Factors to consider in stock selection include surface characteristics, grain, gauge, weight, material density, printing inks or coatings to be applied, and finishing processes to be used. Generally, the stocks most receptive to embossing dies are stocks that are uncoated, heavier in weight, and have a felt finish. Embossing on heavier stocks will most often provide greater dimensional depth and detail. If some of the stock being embossed or hot stamped is thicker in gauge, advise the engraver to "tool" increased depth into the die to give more definition when it is embossed. The greater depth will compensate for thickness, memory, and stock resistance. It is desirable to have the die "bottom out" or strike the paper at the point where the stretch of the material comes close to reaching it's maximum limit without cracking or tearing.

Coated, varnished, or lightweight stocks have a tendency to crack when embossed. Paper and ink have limitations in the degree that they can be stretched before cracking. Coatings cannot be stretched, so care should be taken with any type of embossing on coated or varnished stock. Embossing with foil instead of ink can assist to eliminate cracking on coated stocks. If heat is applied to the embossed die, such as in foil stamping or glazing, it will increase the chances of the coated and lightweight stock becoming brittle, which may cause the embossing process to crack the stock after the die strikes the material.

Textured stocks may compete with the embossed image if the texture is too deep. However, for a blind emboss, a slightly textured stock provides the best results. Consider the direction of the paper grain when embossing or scoring. Emboss and score in the direction of the grain since going against the grain can cause cracking problems. Occasionally, such as with borders, it is necessary to go against the grain to achieve the desired effect. Recycled paper may cause the embossing to be inconsistent in appearance from sheet to sheet, since the higher the content of recycled fibers, the weaker the stock when exposed to heat and pressure. Use paper with 30% post-consumer fiber or less. Long-fiber sheets are the best for embossing, since they are capable of handling a wider variety of embossing dies, particularly the deeper dies. Sulfate and foils are the best board stocks to be used when embossing packaging materials.

Artwork Preparation
Set copy or create images with fonts above 12 point and lines thicker than 2 point. Use images that are more open and have fewer thin lines. Embossing will have a tendency to fill in small, enclosed areas, thin lines, or closely kerned text. Thin serifs do not emboss well unless they are large and well defined. It is generally best to prepare images slightly larger than the size desired. This is to compensate for the resulting dimensional effect that occurs because the paper thickness tends to change the size of the image. For greater depth, provide more letter space in the artwork. Copy or images with very close registration may involve extra work and greater cost. Be careful not to use trapping techniques on any artwork appearing adjacent to embossing and foil stamping. Screened copy and images with changes in tones do not reproduce effectively into dies for embossing, so line art should be created as if it were a solid image or solid color. If a beveled die is to be used, the artwork and copy for the image may need to be slightly enlarged to compensate for the image and copy reduction that occurs due to the beveled edges. Keep images at least 1/2" away from the edge of the stock being embossed in order to eliminate wrinkles that will occur if the embossed image is too close to the edge of the stock.

Presented By
MI Printing
Phone: 623.582.1302