To create an engraved print an image has first to be engraved onto a thin copper plate. This can be achieved either by etching the design or by hand tooling it but in both cases the image is cut into the plate, rather than raised above the plate surface. Nowadays, most plates are etched from computer generated artwork but some hand tooling is often still required on etched plates to capture fine details or rout out larger areas. Once the plate has been engraved its surface is inked and then wiped clean leaving the engravings full of ink. The press then forces paper into the inked recesses and thereby transfers the image onto the surface of the paper by creating an impression. The image is perceptibly raised from the surface of the paper to both the eye and to the touch. The area immediately behind the image carries some bruising and feels slightly indented and this indicates to the discerning viewer that the item has been engraved.
The three dimensional character of engraving and tremendous tactile appeal is reinforced by the crisp, well-defined images that it produces. Engraved printing inks are relatively opaque and their opacity allows the engraving of light-coloured images onto darker paper stocks. They also give a matt finish which is much admired.
Flat Print, more correctly referred to as offset lithography or litho, remains the most popular commercial printing method due in part to speed of production and its relative cost effectiveness. Lithography is based on the chemical priinciple that oil and water repel one another. Lithographic plates have an ink -receptive coating which is activated only on the image area. To prevent ink from invading the non-image area these areas are coated with water. The image is transfered from the inked plate to a rubber blanket and it is the blanket,rather than the plate, that comes into contact with the paper and actually prints the image. The image offsets from plate to blanket, then offsets again from blanket to paper. It is for this reason that the technique is sometimes simply referred to as 'offset printing'.
The result is flat to the touch and is commonly used to print letterheads,business cards leaflets and invitations. These can be in single colour,several colours or four colour process (full colour) but the presses are limited as to the weight of stock which they can accept and onto which they can successfully print. We would be happy to advise on the suitability of offset lithography,often the first process in a job requiring a combination of multiple print process. Another limitation is that the inks are almost transparent and the colours are only true when printed onto bright white stock. When printed onto coloured stocks the colour of the paper stock will show through and distort the printed colour. The darker the stock the greater the show through, so, as a rule of thumb guide, the colour of ink must always be darker than the colour of the stock.
Raised Print, referred to as thermographic printing or thermography, is a modern alternative to traditional engraving (copperplate printing) which is more affordable yet still versatile. The two processes both give a raised finish yet whilst engraving raises the surface of the paper thermographic printing raises the image or type.
A powdered resin is sprinkled onto wet ink, any excess powder is vacuumed off and the sheet passed through a heat tunnel which fuses the powder onto the inked areas of the sheet. The powder swells as it melts and the result is a high gloss raised image.
The process, however, is not best suited to showing fine detail in either typography or logotypes as the heated and now swollen resin 'fills-in' so that fine detail is lost. For a more delicate rendering engraving would be the preferred process.
Equally where compatability with laser printers is required the resin must be UV cured to prevent the heat generated by the laser printer from melting the fused resin again. However, the recent addition of matt thermo powders and metallic thermo powders has increased the versatility of the process such that beautiful effects can now be achieved although the dimples that form on the thermo crust, sometimes likened to an 'orange peel' effect, can preclude against its use in some circumstances. We would be happy to advise on the suitability of thermography for your project.