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Question and Answer

How can I stamp a large solid and fine type together in the same pass?

by Staff

February-March, 1995
Machine Capability
The hot stamping equipment you are using can make a big difference on the success (or even the possibility) of stamping a large solid and fine type simultaneously. The ideal machine for this is a cylinder press. Because the foil is rolled onto the sheet, less pressure is needed to stamp the heavier solid designs, meaning less chance for fill-in on the fine type.

If you are stamping with a clam shell or platen press, several press adjustments must be considered before beginning. First, you must adjust the speed of the press to obtain proper coverage in the large solid area, while still stamping the fine type cleanly. Large designs require slower press speeds while smaller type areas stamp cleaner at higher press speeds. Begin stamping at a slow press speed and speed up gradually until you have reached the speed which will obtain a quality stamp in both areas.

If your press chase contains different heating zones, heating requirements can be regulated for each design. Larger designs usually require more heat to stamp. Smaller type areas can be stamped with a much cooler die face temperature. This advantage is found mostly with the larger sheet-fed platen presses.

The direction the foil is running in relationship to the sheet can also help or hinder the ability to stamp both large and fine type areas in the same pass. When the foil travels with the direction of the sheet, the resulting foil release or stripping action is smooth. When the foil product travels opposite the sheet direction, the stripping action is abrupt and snappy. Large solid designs prefer a smooth release while the fine type prefers opposite direction. If the fine type and large solid are far enough apart and you have the capability of running two foil webs, you can run each in different directions. If this is not possible and the type is in conjunction with or close to the large solid, you are probably better off running the foil with the sheet and utilizing a fine to medium coverage foil product.

Foil Product
Choosing the best foil product is the key to successfully stamping fine type and large solids in one pass. Again, if they are placed far enough apart and you have the ability to run two webs, you can utilize a clean cutting foil product for the fine type and a heavy coverage foil for the solid. If they are close enough together that you can only run one web of foil, you should choose a foil with a middle-of-the-road release that has medium to heavy coverage capabilities. This will give you the best opportunity to keep the fine type from filling and still cover the solid area. Work closely with your foil supplier to help determine the best product for the foil color you have chosen.

To achieve the proper coverage on a large solid and still have enough hardness to stamp the fine type, polyurethane is your best makeready choice. It has just enough give to cover large areas and still keep enough firmness for fine line designs. You may need to build a dome makeready in the large coverage area to help equalize pressure and allow gasses to escape. Gas may build up between the foil and paper stock and cause small pinholes to show in the design. A dome makeready is constructed on a spot makeready sheet that slips under the platen plate. Simple tear 20 lb. bond paper in circular shapes. Tear the first circle in aproximately the size of a dime, the second in the size of a penny, the third in the size of a nickel, and the fourth in the size of a quarter. Place the small circle first in the center of where the design will be stamped, with the others to follow. This can help compensate for more pressure, which is something you want to avoid to keep your fine type clean.

If you are stamping on a porous, dry or textured stock, the possibility of stamping both a large solid and fine type in the same pass is going to be extremely difficult. Dryer, textured stocks will take much more pressure and heat to achieve the coverage of the large solid. Therefore, keeping the fine type clean is nearly impossible. On the other hand, if you are utilizing a quality coated paper, your chances of success will increase greatly if you follow the steps outlined above.

Following these suggestions will not guarantee you will be able to foil stamp a large solid and fine type in the same pass; however, your chances will increase greatly. Remember: trying to cut corners is not always the best decision. You may end up spending more time on press fighting the job instead of producing it.

This Q&A column was answered by Jim Kingsby of JK Hot Stamp Consultants (913) 764-4947. Jim has written several publications on the subject of hot stamping. He currently runs a consulting business, sharing his years of hot stamping experience with clients around the world.