Magnesium is an excellent general purpose Die making material, recommended for short to medium runs. Magnesium die’s will produce good quality 2D, 2½D printing and embossing on laid, woven or textured products. Normal working thickness is 16gauge (¹∕16” -1.63mm), 8 gauge (⅛”- 3.18mm), and 3 gauge (¼” – 6.35mm) [7mm in Mainland Europe]. Magnesium is more commonly available from plate makers as it is considered to be a better product, and is tougher than Zinc.
Magnesium dies are a fast, cost-effective, versatile option for foil stamping and embossing applications. Magnesium is an excellent heat conductor, which is why magnesium dies are primarily used for hot foil stamping applications. These dies are suitable for short to medium runs, up to 100,000 to 150,000 impressions depending on the size of the image and the type, texture and thickness of the substrate. Magnesium is a soft metal, and as a result, its life span is shorter than alternative materials. Print runs of up to 250,000 are achievable but are very dependent on the substrate, machine, machine setup etc. The sharp print impression of the first print may not be achievable towards the end of a long print run as the printing /embossing face of the die is worn out. If embossing, there will be a slight rounded appearance. Magnesium dies are usually acid etched, using nitric acid to create the image. Magnesium dies are a lower cost product when compared to the other metals. Because copper and magnesium are normally etched, the bevels on them cannot be controlled as well as engraved die’s made from for example, brass. Magnesium is a clean etching technology when compared to other technologies and is quick and easy to etch unlike copper or zinc. Magnesium can be hand and CNC machine engraved but because magnesium powder is very flammable special care and extraction is recommended. Artwork with fine detail designs can be easily made in magnesium. When foil stamping with magnesium, and when possible, the paper stock should be smooth or coated. As stated earlier, when using magnesium dies for printing onto recycled or textured substrates, the dies can be easily damaged during the print run and the print setup will be much more difficult than with other harder materials.
When engraving sculptured embossing dies, some engravers prefer using magnesium because of the softness of the metal. Magnesium will however wear out pretty quickly and so, when used for this purpose, it is recommended that duplicates of the sculptured die be made for use in a production run. The magnesium die is retained as the master that can be used to make additional duplicates in the future. Making duplicates for multiple embossing of the same image on the same sheet are an economical cost effective solution.
If the job requires a “one-up” sculptured embossing die, brass is the best choice of die material because of its strength. When cost and or speed are an issue, magnesium is overall the least expensive material and the fastest to produce. When producing 2D and or 2½D magnesium Die(s), the “etch rate” of magnesium plate is approximately 0.18mm or 0.007″ per minute, so an image can be chemically etched to 2.54mm or 0.100” in depth, in less than 15 minutes. This fast, deep etch capability eliminates the need for hand or machine routing of background open areas. Due to the speed of processing magnesium, it is possible to have dies produced for same-day or next-day turnarounds.
Copper is an excellent material for embossing and or hot foiling fine intricate work like crests, logo’s on cigarette boxes, packaging and labels for alcoholic beverages, perfumes etc. Fluted foil Die’s also known as foil embossers are etched and then hand engraved to produce a high quality Die.
Copper is an excellent special purpose material for flat stamping and single level embossing dies. It is an extremely hard metal with good etching characteristics, which makes it an excellent choice for medium to long foil stamping runs. Copper dies are commonly produced on 16 gauge (.064″- 1.6mm) or ¼ inch (.250″ – 6.35mm) however other thicknesses are available. Copper dies are ideal for foil stamping, embossing, halftone, line etchings, and intaglio printing.
Copper and magnesium dies are mostly used for the same applications, but copper is usually preferable for longer runs or when more durability is required. Copper dies are preferred over magnesium for printing onto heavily textured and or recycled papers. Copper is an excellent heat conductor and retains heat longer than magnesium. This means that when printing, the heat expansion factor on copper dies is less than magnesium dies
Copper dies are tough and have sufficient strength and heat conductivity for both foil stamping and embossing applications. Although copper dies are usually used for single-level embossing, they are able to be double-etched for multiple levels. Dies made from magnesium are etched with nitric acid while copper is etched with ferric chloride. With a correct make-ready, and machine setup, copper dies will yield tens of thousands, if not hundreds of thousands of impressions, making copper the ideal choice.
Copper is recommended for print runs of 100,000 to 500,000 impressions but the run length is dependent on other factors such as image size, substrate, machine, machine setup etc. Where medium to large repeat print runs will take place in the future, it is worth considering having copper dies made. This will help reduce the need to re-order dies each time you run the job. Copper as a material is an excellent heat conductor and maintain heat very well. This is especially important when foil stamping on high speed equipment where the speed and action of the press is more likely to cool the die temperature. Copper is recommended over magnesium dies for designs with fine detail and or lines. Copper is also good for embossing with a shallow, somewhat rounded appearance. This is because the edge of the image and or text tends to wear out, especially when printing long runs. Copper can be hand and CNC machine engraveable but as the cost difference between raw brass and copper is not a huge and brass lasting twice as long as copper, customers and engravers tend to use brass as the material of choice.
The surface area and design of the image will determine if copper is the best material for the foiling die. When printing on textured or recycled substrates and or the image has a medium to large area requiring solid foil printing, then much more pressure would be required than a smaller image area and or text. Copper is a hard and durable material and is recommended for use for these types of applications to ensure the die does not begin to collapse under the pressures exerted by hot foil printing machines. Copper is the material of choice if very fine detail images need to be printed because etched copper dies produce crisp sharp edges around the image. Copper is usually substantially more expensive than magnesium, but is less expensive than brass or steel engravings. Copper takes somewhat longer to etch than magnesium, although turnaround times are still relatively quick. The price differential between premium quality copper and magnesium can be anything between 1:4 up to 1:8, so when selecting materials, using copper is expensive and may need to be justified.
Dies made out of brass are considered to be the best and most versatile general purpose die’s for hot foil stamping and embossing available. Brass is generally used when the highest quality die is required, delivering the best in durability, quality and versatility. Although brass can be acid etched, it is rare for that to happen, brass dies are usually CNC and or hand engraved to create multi-level, sculptured or even (long-run) 2D, 2½D flat foil stamping die’s. When hand sculpting, brass is a very good and popular all round material. The die maker can carve the die to exacting detail including fine and intricate designs using engravers chisels and other tools. Hand engraving is often the preferred method of carving multi-level Dies. Brass is an excellent conductor of heat, and is very hard and durable. With the correct make-ready, these dies can be used regularly for many years.
Perhaps the only downside to a brass die is its cost. Although they are very durable, they are expensive to manufacture. Because of the high cost, duplicates created from brass masters are commonly used. Duplicates are particularly useful for regularly repeating jobs, or those that are printed multiple up.
As brass dies are normally engraved they are more expensive then photopolymer, zinc, magnesium or copper dies, but are capable of print runs in excess of 1,000,000 impressions. Brass dies provide sharp, clean bevels, and as they are CNC and or hand engraved, sculpturing is possible creating a number of different edges and angle. Sculptured dies have smooth transition between the various depths, while multi-level dies have any number of distinct levels separated by bevels. Because brass is easily to “work” with, it is an ideal material of choice when an image needs to be “opened” up so that the foil stamps clean without the image filling in. When manufacturing a combination die (an image can be hot foil stamped and embossed in one pass), brass is the best choice because it can be easily machined to create the necessary reliefs to imprint foil and emboss the image simultaneously. Brass is the most expensive material for embossing, and hot foil stamping die manufacture. The cost of using brass has to be justified depending on the type of die required, the print run, the intricacies of the image etc.
The types of dies made from brass, used for embossing and foil stamping, range from simple 2D, 2½D, flat stamping foil images to multi-level and sculptured designs. Brass is a superior material for both machine engraving and hand sculpting. Whenever multilevel, realistically sculpted or special effects are required brass is the preferred option. Brass dies are very hard-wearing and added to that, the dies can be repaired, and that hugely increases the life of the die.
Zinc dies are recommended for runs of up to 250,000 impressions and, is a good cheaper substitute for copper. Zinc is not widely used in the industrialised countries but is very popular in the developing nations. Though the quality of zinc available is poor, it is widely used as it is readily available in these countries. The quality of zinc available in the developed 1st world countries is extremely good; however the process of etching zinc is dirty, slow and expensive.
There are a large number of different types of photopolymer plates and only a few specific type is suitable for hot foil printing. Hot foiling photopolymer plates will normally be able to work at up to 180°C / 356°F. They need to work at about 30°C / 86°F above the temperature required if using magnesium plates. Hot foil polymer plates tend to be used on manual hand machines as the plate needs a few seconds to regain its lost heat when an impression is made. New low temperature foils have been introduced into the market in recent years has helped photopolymer plates make inroads into semi-automatic machines. The main advantage of photopolymer plates is the fact that you can make then in-house with minimal investment.
When hot foil printing, aluminium is a very good low cost raw material with excellent heat absorption, and dissipation characteristics. However it is a difficult material to engrave because it has a tendency to clog and snarl cutting tips / bits very quickly on a CNC engraver. This results in expensive cutters needing cleaning or replacing very frequently. The problem is solved by using specific types of cutters and spray jetting good quality lubricants on the cutting tools and the cutting surface. Aluminium is not a good material for hand engraving as the chiselling tools tend to stick on the material making it difficult to cut intricate designs. As you cannot force feed lubricants as on a CNC system, it is not a material of choice for hand engraving. There are special grades of aluminium with high magnesium content that are used to make hot foil printing Dies. These dies can develop “flat spots” particularly there bold solid are within the image resulting in poor foil transfer in those areas. Aluminium is better suited for cold embossing as a lower cost alternative to brass.
Steel / Stainless Steel
Steel die’s for foil stamping and embossing applications are not generally used, but are recommended for very specific applications. Steel dies are mainly used for very long run (one million impressions +) 2D hot foil stamping on thick card. A steel die would be used to foil stamp cartons for high volume consumer products such as frozen meal boxes, cereal boxes or toothpaste boxes, especially if the print run is likely to be repeated regularly. Steel dies are also recommended for thick, hard to foil stamp materials such as leather and vinyl.
Steel is difficult and slow to engrave and is the most expensive type of die to manufacture. Unless foil stamping very long runs on difficult substrates, steel dies are not an option commonly chosen.
Steel and stainless steel dies are expensive to manufacture and more difficult to achieve a constant steady temperature on the die face when hot foil stamping. Both steel and stainless steel can be etched but it would be fairly shallow and is not an option normally taken for embossing or hot stamping. Etched stainless steel sheets are commonly used to make rotary die cutting forme.
Other Die Materials
Cold embossing dies can also be made from certain plastics such as nylon 66 and other more exotic materials.
Many, but not all, engravers make duplicates for use on multiple-up embossing jobs. An original embossing engraving, usually made from brass or magnesium, is then used to mould duplicates which are exact copies of the original in depth and detail. Duplicates are normally made of one of three different materials, bakelite, fibreglass resin or nickel. Bakelite is a hard phenolic material that’s low-priced and easy to process. However, the heating and cooling associated with embossing limit its durability. Fibreglass resin is more expensive than bakelite, but will last longer. Nickel is a little more expensive than bakelite and fibreglass resin, but is more durable and all are suitable for multi-level embossing or combination dies. Duplicates are the most cost effective way to emboss multi-level or sculptured images that are more than one-up on a sheet.
When using duplicates, it is recommended that you do not mix dups. and metal dies on the same embossing run, especially if you are embossing with heat. This is because metal dies and duplicates have substantially different heat transmission rates. By keeping to the same material, either metal or duplicate, will help prevent running the job at a higher or lower temperature. If mixed then at a higher temperature the embossing with duplicates will be fine but the embossing with metal will be scorched or burned. Similarly if the temperature is low the metal dies will emboss fine but the embossing quality using the duplicates will be poor.