Introduction

Laser engraving text on acrylic / perspex does not create a lot of contrast. This leads to the subject of painting text on the acrylic. I have developed some useful methods of achieving this that I thought I would share.

My techniques achieve a good hard wearing result. One of them allows for painting everything except the text, to allow for back lighting. Note: As I often have to bend and mould Perspex, I needed a procedure that could be implemented on the final moulded pieces. This meant that using a laser cutter to remove paint was not an option.

Technique 1, Painting the text.

This effect is a little more difficult than would appear at first glance. You want to paint the whole area and remove only the paint that’s not in the text. Problem is doing this by washing with solvents will thin the paint and dilute the finish, reducing the contrast. There is a neat trick you an use however, it involves pouring water over an oil based paint to form a gum in the lettering, which is resistant to solvents.

• Laser engrave the text with a deep cut (1mm -ish).
• Prepare the piece (bend, polish etc.)
• Spray paint with a cheap oil based paint (the kind that gums with water). The “Fiddly Bits” brand works well.
• Wait 30sec to a minute.
• Place piece under running water for a couple of seconds.
• You should now be looking at a complete disaster, the finish is ruined and everything is a kinda horrid sticky mess.
• Get a thin micro-fiber disposable cloth, dip in turpentine.
• Scrub the surface (will require elbow grease and persistence).
• Presto, the only stuff you cant scrub out is this awesome looking text.

Technique 2, Painting everything that is not text.

This seems like an odd way of doing things, but offers some interesting advantages:

• Done on translucent acrylic, you can now do back-lighting
• You can paint gradients / flames etc. and still have blacked out text.
• You can always find the right coloured paint on short notice, while acrylic colours are at the mercy of your supplier.

This technique is actually a lot simpler than the first technique, but a lot less forgiving to errors.

• Engrave text with the quick shallow cut. You basicly just want to rough the surface.
• Prepare the piece (bend, polish etc.)
• Wipe turpentine over the piece with a cloth.
• Gently (half) dry the surface with a dry cloth. Leave the thinnest smear don’t dry out the letters.
• Wait 20 seconds to allow for some evaporation to occur.
• Spray paint a very thin layer.
• The text area will still have some turps, and also possesses a higher surface tension due to its roughness.
  • The paint will move away from the text forming on the flat, smooth areas.
• Repeat coats using this procedure as needed.

   
(Left, final product. Right. first coat)