Want to paint underside of my PEI for IR sensor, any non-baked finish?

  • I would like to paint underside of my PEI for my upcoming build, but I do not have access to an oven to bake a BBQ type paint. Has anyone used standard spray paint? I see that it has a max temp of 93C which is below ABS recommended bed temps. Also there is spray engine enamamel which has max temp of 260C and doesn't require baking, but flattest black is listed as low-gloss. There is also option of just using the BBQ paint and using the bed to heat it up and cure before adhering. Any suggestions?

  • I don't use PEI, but I just painted my glass with the BBQ and put it on the bed.

  • I dont see why the engine enamel wouldnt work, just go in very thin coats to be sure an even reflective surface

  • the engine enamel doesn't tell you to cure it because the the heat from your headers or the engine block (what ever you painted) actually cures it. you may get the same effect by painting the pei and after its dry placing it on your heat bed and letting it sit on there at temp for an hour or so.

  • I have a 450mm x 350mm PEI covered bed that has been sprayed on the underside with Matt black fast drying paint. Didn't fancy risking the oven bake method as I get too many burnt offerings from the oven already. The paint I used was from a well known automotive brand and required 24hrs of drying to harden. Being skeptical of the adhesion properties I subjected the painted side to the good old masking tape rip off test and all was good. The PEI is in 0.8mm thick by 10" square sections laid out in a staggered pattern on 3M 468MP adhesive sheets. The sheets were glossy and gave me a few problems with reflectivity and David's excellent IR sensor. A few failed prints later I read about 'scuffing' the surface so got hold of a 3M Superfine abrasive pad and haven't looked back since. PEI has been a great surface for a range of filaments with a few more yet to try.
    Apologies for a long 1st post but this controller and the support given on this forum is absolutely awesome.

  • So you are saying that if we scruff the PEI sheet it doesn't need painting?

  • Yes by giving the surface a dull sanded appearance the IR sensor picks it up

  • Will test this with some 1200grit paper I got lying around. Thanks for the reply 🙂

  • @minim:

    Will test this with some 1200grit paper I got lying around. Thanks for the reply 🙂

    Did this workout for you? Curious as I'm looking for a solution for IR and PEI.

  • i think painting the pei surface is a bad idea. Unless you paint it perfect, once you get the heater part of the paint becomes detached and goes onto the heat spreader, or some other surface, then, inevitably you try to remove a print stuck on the bed, the pei moves a bit, then your auto calibration is all wonky because of the black bits missing,

    I found a better solution is to just get a dark colored file folder and cut it to your bed and place it under the pei.

  • Wonder if just roughing up the surface and then using a big permanent marker to color the PEI would do the trick.
    It's crude but the marker would get stuck in the scratches on the surface. Can later wipe off most of the marker.

  • After painting, make sure you wipe it down with a tack cloth to remove all the paint particles that did not stick to the surface. If you don't do that, the adhesive will stick to the particles and not to your PEI sheet. You can also use a sticky tape to remove the paint residue.

    There are some Ebay and AliExpress vendors selling PEI Sheets in black color now. I just ordered a few to test. I am not fond of painting the PEI due to the hassle. Even when you think you painted all the surfaces, as soon as you put the sheet against a light source, you will see areas that did not have enough paint. I had to add light coats of paint at least 4-5 times before I was happy with the results.


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