What’s the difference between photopolymer plates and magnesium plates?
Magnesium plates are much thicker and heavier than photopolymer. Because they’re often mounted at type high, they take up more storage space than thin polymer plates (which can be stored in a filing cabinet). Magnesium plates also require more maintenance if you want to keep them around. After letterpress printing, you’ll have to coat them with an oil or grease, such as Vaseline or vegetable oil, or else the plate will oxidize over time and render the plate unusable. To keep costs down, many printers use magnesium plates with wooden bases. If you use too much oil on your plate, then the extra oil could sink into the wood and potentially warp the wood base. Using wood as a base also has its own weaknesses: the wood warps with changes in atmosphere conditions and requires a lot more make ready than polymer. Photopolymer does not need any coating to protect its surface for storage. If you store your plates in a self sealing / zip lock bag in a cool, dry place away from UV light, your plat
