How to Apply a Liquid Coating Around a Ceramic Cylinder?

Mask the top of the cylinder with tape, put it on a lazy susan and spray the coating on.

These Preval (not an endoresment) work really well. You can get then at most professional painter's supply stores.

They're like a spray can that you fill your self. I've used them many times. Be sure to keep shaking the ink to keep the conductive particles suspended.

You may have to thin the coating with solvent and apply multiple coats.

PRACTICE FIRST!

Preval ProPack$14.99

Not much detail.

Dip it?

Put it on a lathe?

Incorporate the ink into the glaze on the cylinder?

Lay down an ink pad and roll the cylinder over it like a rolling pin?

Dipping requires a controlled withdrawl from the fluid for an even coating. Contrary to what you might think, fast removal gives a thicker coating and the rate must be varied for consistant thickness. I spent 3 months experimenting with an automated dip coater before getting the process right. Viscosity matters a lot too.

Also, dipping requires careful masking of both ends and lots of ink, depending on the size or the mystery cylinder.

I like the other three ideas, Grasshopper.

Spraying works well. I used to spray silver filled coatings and radar absorbing coatings on satellite parts.

Not a consistent question either:

What is the size of the ceramic cylinder?

How precise is it made?

What is the reproducibility - is it a series production or a single shot.

Coatings can be applied many ways:

typical rolling coaters are knife over roll, 2 roll with knife (or scraping blade), roll over roll. There is always an applicators and a thickness adjuster.

If your cylinders are not machined, you can always try to spray as mentioned by Lyn.

A rotating table can help a lot. Most precision you will get with diluted multi- layer applications. It all depends what on what you call conductive.

You have conductive like a metal coat or something resistive to measure on.

You can metalise it with a flame gun too. Or use an electrolytic system when the cylinder is hollow and the wall is thin.

Well, vague questions certainly generate speculative answers! Thanks for the thoughts so far. The ceramic cylinders are 1/2 inch diameter at maximum, 2 inches long w/ 2 concentric decreasing diameters. They are production made. Coating must be consistent and thin but I don't know the exact specs. That's all the info I have.

That rules out dipping, rolling, doctor blading, and most other processes.

Vacuum deposition might work, or

Wait, what is the coating???? That's critical.

Get more info.

Do you want to cover the full surface or only part of it ?

If full think about a 2 roller support. If part only, screen printing can be a solution. Of course with a special coordination between rotation (cylinder) and translation (screen).

Screen printing is broadly used in integrated circuits on ceramic support. Conductive inks are available with different viscosities and specific resistance (Ω/square).

As nickname says there are many different inks depending on the resistance. Some are fairly thin & air dry others are viscous & have to be fired, what are you using? We use different inks on ceramic some are screen printed but those on cylindrical surfaces are hand painted with the cylinder on a turntable. I can imagine a pad printing set up where the cylinder is rolled across the surface of the pad but I've never seen this done.

This is an entirely different approach, but an interesting one. They incorporate the conductivity into the ceramic cylinder itself:

http://www.piceramic.com/pdf/KATALOG_english.pdf

This is possible ONLY if there is no risk of electrical contact between cylinder internal surface and any other element of the circuit which is not always the case.

So, this is what it feels like to be used, and then tossed aside.