Foil stamping is a printing process that applies an image from foil to a substrate, usually paper, board or plastic.
Foil stamping operates in the same manner as letterpress printing except that it uses heat and a stamping foil rather than ink to apply the image. Conventional letterpress masters are used (i.e. images raised) and letterpress machinery is also used. Stamping foil consists of (1) a carrier layer of polyester, (2) a release coat, (3) a coating of metallised aluminium or pigment and then (4) a layer of sizing material. When foil stamping a job, heat is applied by the die to the polyester side of the stamping foil and this heat softens the sizing coat which adheres to the substrate and releases the metallised or pigmented section from the carrier onto the substrate.
The two types of foil most commonly used are Metallics or Pigments, metallic foils come in a range of colours including silver and gold and have a shiny metallic finish to them, pigment foils have a dense solid cover of pigment and give a dense opaque finish.
Multi colour or rainbow foils are also available, which have a random pattern of colours applied to them and when stamped can create interesting and colourful effects.
Diffraction foil has a light reflective pattern embossed onto the metallising and holographic foil has a hologram embossed onto the metallising.
Points to remember;
- Never reverse out foil stamping images from print.
- Discuss layout for multiple images to obtain best usage of foil.
- Coating and varnishes are generally OK although if the image is bold it would pay to check with us before proceeding.
- Excessive spray powder can cause problems with foil stamping.
- Selection of stock is important.
Stock requirements for Foil Stamping;
- For all embellishment processes there are stocks that can be used successfully and stocks that do not suit the particular process. It is very hard to accurately define the requirements for stocks as there seem to be variations in quality and make up of similar stocks from different mills. A good example of this is a cast coated stock where product from one mill can withstand deep sharp embossing while a similar product from a different manufacturer is totally unsuitable for embossing as it cracks and splits very badly. There are however some broad basic requirements for the techniques and these are detailed below;
- The best surface for foil stamping is smooth, clean, regular and stable, such as is found on cast coated stocks and art boards.
- Normally textured cover stocks can be foil stamped quite successfully although at times a slight depression in the image may show as a result of pressure required to flatten the surface to obtain complete coverage of the image.
- Some papers can be difficult to foil stamp and it appears this may be due to the sizing chemicals used in the manufacture of the stock.
- The best stocks for foil stamping give a fast relief which means that the die and foil are in contact with the stock for the shortest possible time. This eliminates most of the common foil stamping problems including flooding, dulling of the image and gas entrapment.