Member Login

Remember Me
Forgot Password?
Join Us!

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

Join Eng-Tips
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Link To This Forum!

Partner Button
Add Stickiness To Your Site By Linking To This Professionally Managed Technical Forum.
Just copy and paste the
code below into your site.

Electrical Conductibility of varnish

Electrical Conductibility of varnish

Hi guys,

I was wondering how to measure the electrical conductibility of a varnish? My problem is that we would like to estimate is the conductibility of a varnish we would like to use in a magnetic application.

Can anyone give me a link to references / norms or something else?

Thank you for your help!

RE: Electrical Conductibility of varnish

Vanish was used as an insulator for wire and transformer winding for many years and should be an excellent electrical insulator. Do you need the actual value for conductivity?
A modern equivalent material used on wire is "formvar".
Is it really the dielectric constant or breakdown that are more important?

RE: Electrical Conductibility of varnish

oops, my english is not so good... I was talking of a protective painting (Interplus 256, which contains Al and Mica).

In fact we said "it's conductive", but we would like to quantify for the internal report, in a correct way.

it is really important for our application that no conductive material is used (because of high magnetic fields)...

RE: Electrical Conductibility of varnish

Why not just paint a strip and do your own measurements?   

Thomas J. Walz
Carbide Processors, Inc.

Good engineering starts with a Grainger Catalog.    

RE: Electrical Conductibility of varnish

If neither the varish nor the magnetic field is moving, why is there a problem with conductivity?

What do you mean by "correct way?"  One method is to use a Vander Pauw test pattern.


FAQ731-376: Forum Policies

RE: Electrical Conductibility of varnish

Both are turning (paint on a rotor, magnetic field is alternative...)

RE: Electrical Conductibility of varnish

I haven't seen anything on the IPC website to suggest that the resultant coating is conductive.  256 contains micaceous iron oxide, not mica.  

What exactly is the concern about conductivity, given that you're painting a conductive rotor?

For sheet resistivity see:  

I would start with a high-end PC board with 4 symmetrically placed electrodes, mask off the center and the external contacts, and coat and cure per your procedure.  Get a high end, Kelvin-connected resistance meter and have at it.


FAQ731-376: Forum Policies

RE: Electrical Conductibility of varnish

in fact the rotor is not conductive at all... and it must be insulated because of the technology used. So I have to be sure that the corrosion protective painting is absolutely insulative and not conductive...

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close