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The History of the Photopolymer Letterpress Plate

By September 13, 2023News

When it comes to letterpress printing, plates are key – and there are lots of different options available for these. Lead type, wood type and magnesium plates are all good choices for letterpress printing – but a photopolymer letterpress plate is something a bit different. When you opt for photopolymer plates you’re choosing a very modern material for your letterpress printing – and this tends to mean more versatility, convenience, and a wider range of design options too.

What is the history of the photopolymer plate?

Letterpress printing itself goes all the way back to the 15th century and the basics of how it is done today are very similar to the way that it has always been. For centuries, any printed materials have been created using metal plates, often containing a single letter, and which had to be painstakingly positioned in the right place before the printing could be done. Mechanical typesetting arrived in the 1800s and was something of a game changer in terms of the convenience of letterpress printing. Nevertheless, letterpress printing on a mass scale was eventually replaced by offset printing. However, for those who were keen to retain letterpress printing methods, there was a challenge in terms of the time consuming tradition of hand setting. Many letterpress printers were looking for a more accessible way to print – and that’s when photopolymer plates came along.

How does a photopolymer plate change things?

Essentially, photopolymer can replace movable type. So, instead of setting a block of text one letter at a time, with a photopolymer plate a digital file can be used to create a single photopolymer plate. The major advantage of this is that there is no limit on printing in terms of the amount of type that someone has available to them – because more type can always be created with photopolymer plates.

But what is a photopolymer plate?

It’s basically a sheet of photopolymer with one side that is light sensitive. When you’re creating a photopolymer plate, a digital design is transferred onto a photo negative that is then put on top of the photopolymer sheet. Then the design and the photopolymer are exposed to light under controlled conditions. While most of the photopolymer will remain soft and pliable, those areas that have been exposed to the light will harden. The plate is then washed and rubbed with a soft brush that removes the areas of the plate that have not hardened. The plate is then baked so that it is easily able to take the pressure of the letterpress printing process. Because they tend to be thinner than the average plate, the slices of photopolymer that are used in letterpress printing can be adhered to an base, either, wood aluminum or magnesium, that raises the plate to exactly the right height for printing, this is referred to as Type High, (23.33mm or 0.918inch). Once this is done then the photopolymer plate can be inked and it is ready to go.

Photopolymer plates are the future of letterpress printing, providing a simple and efficient way to create whatever design you want, all available with daily dispatch from Metallic Elephant.