While photopolymer and thermoformed signs are similar, there are many differences
between the two methods and overall customization of the signs.
A photopolymer sign is a one piece sign created from a polymer resin (clear plastic in a
liquid form) that is hardened to form a plate. 1 That plate is fused with a PETG base in the
hardening process. A film negative is placed on top of the photopolymer and both are then set
under UV lights for about four and a half minutes while the UV rays pass through the clear areas
of film negative and expose the photopolymer material. The UV rays harden, or set, the
photopolymer that is exposed. Next the photopolymer is washed in clean tap water during a
‘Washout’ process. The photopolymer that was unexposed to the UV lights is washed away and
what remains are the exposed raised photopolymer images. After drying and post exposure, the
signs need to be cut out of the sheet of photopolymer using an acu-cutter. Lastly, color is
applied through a process called ‘Hot Stamping’, by laying colored foil onto the sign and using
heat to transfer the colors from the foil onto the face of the sign. 2
The process to create photopolymer signs is pretty neat but lacks the room for a lot of
customization. Additionally, this method is not typically used to make exterior signs as the color
from the Hot Stamping method can be easily scratched off.
Creating thermoformed signs might be more time consuming than creating photopolymer
signs but the end product is well worth the effort. First the mold for the sign is created, using a
phenolic material. Next a non-glare acrylic sheet is placed on top of the mold. Optionally, tac-fil
can be added into the mold before placing the acrylic sheet on top. The acrylic sheet is exposed
to high heat and compressed into the mold (or if tac-fil was added, fuse acrylic and tac-fil
together) to copy the shape of the mold. After the sheet cools, any imperfections on the raised
characters will need to be sanded down. More than one sign can be made from one sheet of
acrylic and each will need to be cut out using an acu-cutter, just like the photopolymer signs.
From here a number of routes can be taken. If second surface painting is required, paint is
applied and then backed with a vinyl protector. Otherwise, the sign can be painted first surface
and in both cases a screen printer is used to apply ink to the tactile, if necessary.
The thermoforming method offers a lot more room for customization as a mold can be
made for anything and any paint color can be matched. Both interior or exterior signs can be
made through this process as it is vandal-resistant, extremely durable, and all paint and ink that
is used, works well for interior or exterior use.
Which process does Signs PDQ offer? Thermoformed.
1 “Differences Between Photopolymer and Thermoformed Signs.” Encompass Sign, 09 May 2016, http://www.encompasssign.com/blog/differences-between-photopolymer-thermoformed-signs
2 “How To Make Photopolymer Signs.” Nova Polymers, https://www.novapolymers.com/resources/how-to-make-photopolymer-signs/