Rounding off the edges.

"Only potential problem is that according to my calculations it contains 16% Chromium w/w so not sure if this would pose a major problem."

I strongly doubt that 16% W/W will have much, if any effect - Presumably the chromium is not in elemental form, but in the form of salt or oxide or whatever - so its going to come down to the conductivity of whatever molecules its 'in' and how these molecules are distributed (their proximity) in the total compound..

You see, it probably all depend in whether there is any conductive 'skin' or layer in the final dry coating - if the 16% chromium formed a layer, it could be as bad as "space blanket" which has a tiny quantity of aluminium deposited on a non-conductive plastic - the aluminium is probably < 10% of the total mass, but behaves capacitively as if it was all aluminium foil.

Most likely though, the molecules will be quite low conductivity and spaced far enough apart that the effect will be minimal.

Fred.

Hi Fred,

I hear what you are saying!

Anline Black is a big molecule with a huge amount of conjugation and only 3 Chromium ligands bonded to it with, I suspect, some charge transfer action going on between the Cr-ligand complex and the main molecule, all of which would explain why it has such an absorbance.

Given that, I suspect that there won't be much room for electron transfer between the Cr atoms themselves. I could be wrong but will give it a test when I can lay my hands on a tube of the stuff :-)

Edit: have just done some searching on the stuff and apparently these polyanilines are well known for their electrical conductivity!

LOL!
Well I did say I could be wrong...LOL

"and apparently these polyanilines are well known for their electrical conductivity!"

Well, fascinating!

To me, there is a real irony here - Go looking for substances to make conductive paints, and all you find is carbons or elemental metals like silver in high (expensive) concentrations.. Go looking for non-conductive paint, and you find something that I have never come across in my searches - "polyanilines"

Most of the cheaper conductive paints (and theyr not that cheap) have properties that cause difficulty, and are mostly (exclusively?) carbon based - a low cost, non carbon conductive paint would be great - particularly if it was tough / hard wearing.. unlike this http://www.bareconductive.com/shop/ which is a water-soluble joke.

It really does surprise me that no-one has made a reasonable conductive ink/paint suitable for 'drawing' low power circuit boards - or ideally suitable for ink-jet printing.. Also surprises me that highly conductive toner hasnt appeared. The ability to produce prototype boards without etching or milling would speed up development boards hugely, and could be a massive market...

But in sure plenty of people have realized this, and there must be damn good reasons why it hasnt happened..

Fred.

Hi there,

I'm new to the forum, however I'm impressed by the posts from the various technical experts.

 As a left-hander, I bought an LV3 to see if I could get the feeling that I could convert across from playing sax's, basses and synths. I really liked this entry level theremin and decided to buy an etherwave plus kit and then convert the pitch and volume antenna around and mount the pcb upside down so that it would be for left handed playing and the controls being more easily accessable (saw a thread about this).

My question is not paint, but glue. I used Wickes high strength contact adhesive to stick the ends back after swapping them around. I'm having real grief getting the volume antenna to work and was wondering if the glue could be causing this? The pitch works okay, however we are talking science here and my Heath Robinson mod may be breaking some rule or another.

Hi myesol

I've had a look at the data sheet for the adhesive and as far as i can see there should be nothing in the adhesive to cause any problems.

Should smell nice though! LOL

Someone else might be able to offer some insight into potential problems with converting into a lefty.

R

PS-still investigating the aniline black dye...stay tuned!

Thanks Roy for your reply.

I'm a bit miffed that M00g can sell a kit with instructions and pictures that don't quite match, yet go on about it it being relatively simple to configure, yet it clearly is more sophisticated than just soldering a few wires on a board.

Granted I'm learning things, which I think are important when you own any instrument, however having to start checking whether components have varying currents flowing through them is not what musicians do.

Ok, an update.

So here was I ready to go ahead with the aniline black sealed in with a few layers of Danish oil when a little birdy birdy, with it's little beaky beaky whispered in my ear...

'lacquer'

:-)
NB-Fred, the aniline black seemed to be pretty conductive in the wet but not so in the dry.

"NB-Fred, the aniline black seemed to be pretty conductive in the wet but not so in the dry." - RoyP

Fascinating and surprising!

I have usually found conductive paints etc go the other way - no conductivity until dry! this aniline black is quite a weird compound though - do you know what the solvent for the paint is? Is it a situation where the solvent and the dry substance form a different compound when mixed?

Is there any measurable conductance on the dry aniline black?

Fred.

'lacquer'

was that black lacquer ?

The solid material is filtered through cotton and spun in a centrifuge to remove bark and other contaminants. The product at this stage is suitable for use as a base coat, but must be further refined to be used for middle and final coats. Iron powder is then added to tint the base lacquer black or red.

http://www.ehow.com/about_6307828_black-lacquer_.html

‘Fascinating and surprising!

I have usually found conductive paints etc go the other way - no conductivity until dry! this aniline black is quite a weird compound though - do you know what the solvent for the paint is? Is it a situation where the solvent and the dry substance form a different compound when mixed?

Is there any measurable conductance on the dry aniline black?’ – Fred


Fred, these were quite crude tests, I stuck a pair of electrodes into a capful of the paint, as it was out of the tube, and it conducted, as it did just after I spread it over an area of about 12x6” paper. When it was dry, it no longer gave a reading on my trusted DMM (i.e. open or very high resistance).

The paint is in aqueous solvent so it’s either a water or alcohol suspension.

Strangely, if my original idea holds, this would suit these findings and also the ones with which you are more familiar. Strange really.


‘The solid material is filtered through cotton and spun in a centrifuge to remove bark and other contaminants. The product at this stage is suitable for use as a base coat, but must be further refined to be used for middle and final coats. Iron powder is then added to tint the base lacquer black or red.’

Thanks for the info on ‘black lacquer’.

I had puzzled over this after the little birdy tweeted in my ear but then spoke with a friend who is a furniture maker: he suggested that many people use the terms ‘lacquer’ and ‘French polish’ interchangeably, which made me do a little digging and I came up with this…

http://pianomaker.co.uk/technical/polishing/

If you look at points 134 & 135, Gas Black colourant is soot (a.k.a. carbon or charcoal but when used for ebonised work is augmented by aniline spirit black (there’s that stuff again!).

In 135, ‘black polish’ for use in ebonised work is a mix of white polish (light delicate hue) with aniline spirit black, this black polish is used over existing layers to impart an ebonised look.

Had another wee look around and found that ‘Liberon’ do a black French polish, as supplied by Axminster Tools ( http://www.axminster.co.uk/liberon-black-french-polish-250ml )

Might just have to put in a wee order and have a go…


N.B. (1) I have no vested interests in any of the companies mentioned above!
        (2) The little birdy birdy was a reliable source.

Hello Roy,

to be honest, im sure your "little birdie" is right - at a practical level anyway..  I am just indulging my obsessive curiosity about everything! (not to mention my pedantic nature ;-)

Some change in the "conductive" environment is completely acceptable - its probably only when coupling is altered by perhaps a pF o that one may even notice (as in, a distributed conduction 'layer' which, in relationship to antenna / circuit / ground, which actually "imposes" a capacitive coupling between elements) - and with the distances involved, paint would probably need to be quite conductive to do this.. and even if it did, a pF could probably be trimmed away without much bother.

My curiosity is mainly about the nature of colorants, particularly black... For some daft reason I thought of tar, for example, as somehow not carbon related.. But found I was wrong.. The same has happened for every black thing I can think of - all seem to have carbon or iron or some other conductive or potentially conductive properties.

Have actually been wondering about colorants in plastics - ABS etc.. But its been difficult to find any real data.. I wonder, for example, whether a black ABS box or tube has different electrical properties to a white (or natural grey) one.. And this issue extends to plastic tubes - I have used Tufnol tubes for antenna extension and know these are fine (resinated paper / cotton) but are expensive - and have been looking at bog-standard cheap plastic pipe.....

Also, it seems its also probably safer not to wind a coil onto anything black! ;-)

Fred.