I bought this stamp making material from banggood. Get yours too here.Supposed to work by photolithography. It is made from a supportive material, covered with sticky polymer and topped by a protective transparent plastic layer.
The sheet as advertised on banggood
Close-up view of the three layers
I designed a small test stamp model. It's 20x20 mm
The stamp model
I tried to expose it with 230 W of UV LED /m2 but it did not work even at long exposure time (1 h). So I ended up using my laser etcher to expose it. The shape to remain positive is exposed by laser beam.I used LaserWeb to generate the code out from my SVG design. Then I used CNCjs to send the gcode to the laser.
Screenshot of webLaser GUI, forgot to mirror the image, gloops
My laser module is 2500 mw 445nm. I adjusted feed speed and laser power intensity. Here are the results:
Results after different laser exposure
From left to right:
- Laser at 20% power, moving at 1000 mm/s: too much energy delivered, the material is burning
- Laser at 5% power, moving at 1000 mm/s: still delivering too much energy
- Laser at 3% power and 2000 mm/s feed
- Laser at 3% power and 2000 mm/s feed, 4 passes to expose increase exposure without burning the material.
Then, the whole stuff is let in water overnight. Unexposed parts will have swollen and gotten softer. The exposed parts should remain harder. Try to gently remove most of the swollen material using a brush but be careful since you could accidentally scrap exposed parts. The swollen material might be difficult to remove from intricate detail. That is not a critical issue since it will retract when drying.
Here is the final results for the stamp made using laser at 3% power and 2000 mm/s feed, 1 pass. Increasing the nimber of passes can help reduce roughness, especially if laser scanning direction is crossed, but could cause some exposure laterally of exposed parts.
Final stamp result