Painting FP4 Thermoplastc Polyurethne (TPU) protective case

Any ideas what materials the protective cases are made of, and how they could be painted? I find the color choices rather limiting, didn’t really find a lot of other sources for more choices, and would like to figure out what kind of primer + paint etc. I could use to get one in another color.

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You can ask Fairphone for a definitive answer, else like the general user there is the information they provide on the shop site.

Made from non-toxic 100% pre-consumer recycled TPU (Thermoplastic Polyurethane),
Fairphone 4 Protective Soft Case - Accessory | Fairphone

You may also like more info on the TPU

Sounds like an interesting project! :thinking: Would you mind keeping us updated of your progress? I’d love to try to paint my case as well if I got the time in the future

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I am firmly convinced that you can do whatever you want, it will not work.
Everything you put on top will not last.

But let’s try it. Worst Case: You throw 40 Bugs away…

Besides, the data sheet says exactly what kind of material it is: TPU (Thermoplastic Polyurethane).

I am also pretty sure that PU cannot be painted.

Best wishes,

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Oh, thanks. I read that page a couple of times and somehow missed that specific text - I just saw something about it being recycled materials.

You can probably use linseed oil paint. There’s very little it won’t adhere to. Including dusty surface and silicone. You could try a few dots around the edges to start with :slight_smile:

You can try pure linseed oil with no colour to see how well that looks and feels. The problem is the drying time. You can use boiled linseed oil but the drying time is the clue. The longer drying time the better adhesion as the oils has more time time to ‘bond’ with the surface before it becomes a surface coating in it’s own right.

Try on another similar construct first to get a feel and drying times, personally I would not do it or use linseed oil, but it will adhere I’m pretty sure of that :slight_smile:

Maybe adding stickers would be an alternative.

As long as the case is free from contaminates like oil from the hands any slow drying and flexible paint will do, hence the notion that linseed oil would, even if the case was dirty.

To get an idea of linseed oils ability. I have a wooden cabin that I coat in linseed oil rather than paint. I can coat it numerous time without having to prepare the surface. However if drops get on the windows it takes a lot of elbow grease (effort) to dilute and scrub it away. Unlike modern hard drying paints that can be scrapped off the glass. Removing linseed oil is consuming.

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I wanted the “Fairphone” letters on the bottom of the case to stick out more. So I painted them with standard nail polish, a little diluted with isopropyl alcohol that I had lying around and a small syringe. Since the letters are “stamped” into the case, the nail polish adheres without a problem


I have used clear nail varnish on screens to keep the damp out, hold the glass together and smooth it over, but I thought it may be too brittle/stiff etc for a flexible cover :slight_smile:

Deutsche Anleitung zur Lackierung von TPU:

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Google for a suitable “Primer” – you have to paint this base layer before applying the color paint to make the latter adhering to your FP. case.