I am thinking about stator coatings for perforated steel stators. 😕
I sprayed liquid tape on a piece of copper and tested it with high voltage. It is hard to get an even layer and the result was arcing with a couple of thousand volts. Pretty useless for this purpose. 😡
It seems like acrylic clear coat has been used by forum members here. Rattle cans are quite expensive here and I dont know if I will get an even coverage. I am thinking about getting acrylic clear coat for floors. Then dipping the stators in it and then hanging them to dry.
Any thoughts on this?
I sprayed liquid tape on a piece of copper and tested it with high voltage. It is hard to get an even layer and the result was arcing with a couple of thousand volts. Pretty useless for this purpose. 😡
It seems like acrylic clear coat has been used by forum members here. Rattle cans are quite expensive here and I dont know if I will get an even coverage. I am thinking about getting acrylic clear coat for floors. Then dipping the stators in it and then hanging them to dry.
Any thoughts on this?
Don't use any thing that is water based.
You won't get a good even coat by dipping and it will just be more of a mess than you realize.
Do use a Primer coat, Use only the red kind as it is loaded with Talc as a filler and this is good.
Red doesn't have Titianium Dioxide or Carbon black as a pigment, Gray and Black primers do, This stuff conducts at high voltages.
After the primer it is okay to use a thin color coat of your choice and after that finish them off with several coats of Clear.
You will need at least 8-10mil of thickness if not more.
Yes, spray bombs can be costly unless you can find a good deal on them, clear is what you will need the most of.
If you have a sprayer then you can use Bulk paints of the automotive type.
Sometimes you can find the Dielectric Breakdown in their data sheets, as static charge and pump fires have been an issue in the past.
Liquid tape doesn't work worth a hoot for this application so don't waste you money on it I have already tried it.
I get 1500v to 2100v per mil of dielectric strength with common spray bomb Acrylic paints only if they don't have any pigments that are conductive as mentioned.
Read through this whole thread for more info on this,
http://www.diyaudio.com/forums/plan...tric-coatings-fact-fiction-2.html#post2894427
You can also have them Powder coated as this will form a great base.
But chances are you will still need to re-coat them with a heavy coat of clear Acrylic due to micro cracks.
I had done this on my second set of wire mesh stator Desktop ESL's (they were black in color).
They worked great until I burned them up in some very extreme testing just to find out what their limits were, the limits were very high.
I had as much as 25Kv p-p across the stators before without any breakdown with a .150" stator to stator spacing and 5Kv to 7 Kv of bias on the diaphragm.
This thread shows my whole coating process using spray bombs,
A Segmented Stator Desktop ESL
Here is a picture sample of my results that can be found in the above thread and a Picture of my Powder Coated wire mesh version the very night I burned it for the last time. 😉
jer 🙂
You won't get a good even coat by dipping and it will just be more of a mess than you realize.
Do use a Primer coat, Use only the red kind as it is loaded with Talc as a filler and this is good.
Red doesn't have Titianium Dioxide or Carbon black as a pigment, Gray and Black primers do, This stuff conducts at high voltages.
After the primer it is okay to use a thin color coat of your choice and after that finish them off with several coats of Clear.
You will need at least 8-10mil of thickness if not more.
Yes, spray bombs can be costly unless you can find a good deal on them, clear is what you will need the most of.
If you have a sprayer then you can use Bulk paints of the automotive type.
Sometimes you can find the Dielectric Breakdown in their data sheets, as static charge and pump fires have been an issue in the past.
Liquid tape doesn't work worth a hoot for this application so don't waste you money on it I have already tried it.
I get 1500v to 2100v per mil of dielectric strength with common spray bomb Acrylic paints only if they don't have any pigments that are conductive as mentioned.
Read through this whole thread for more info on this,
http://www.diyaudio.com/forums/plan...tric-coatings-fact-fiction-2.html#post2894427
You can also have them Powder coated as this will form a great base.
But chances are you will still need to re-coat them with a heavy coat of clear Acrylic due to micro cracks.
I had done this on my second set of wire mesh stator Desktop ESL's (they were black in color).
They worked great until I burned them up in some very extreme testing just to find out what their limits were, the limits were very high.
I had as much as 25Kv p-p across the stators before without any breakdown with a .150" stator to stator spacing and 5Kv to 7 Kv of bias on the diaphragm.
This thread shows my whole coating process using spray bombs,
A Segmented Stator Desktop ESL
Here is a picture sample of my results that can be found in the above thread and a Picture of my Powder Coated wire mesh version the very night I burned it for the last time. 😉
jer 🙂
Attachments
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It was from TCI (PCI?) I think, I never did find out exactly which one it was.
It was a freebie done by a local coater back in 2003 just to prove the concept and he made me a few samples that I had double coated in order to make it work.
So, I only had enough material that surpassed the tests to build one pair of panels.
I picked up a jar of some PC material from a local Habor Freight tool store that I want to try to use to duplicate my original panels.
All I know is that the new stuff I have was made in India but it was only $5 for a 1lb jar of it.
If you do choose to do powder coating don't expect it to work perfectly, as many have tried that route and have had it fail or eventually fail.
But like I said it does make a nice base coat to start with if you can do it cheap enough.
However only my second sample that I had made worked and later I had to re-coat them using clear acrylic.
The very First sample the guy did, he handed it to me rolled up into a tube and when I got it home it miserably failed my High Voltage tests due to micro cracks.
Here is one description and some pictures of when I refurbished those panels, there are many more posts and close ups of them in this thread,
http://www.diyaudio.com/forums/planars-exotics/109789-esl-diaphragm-coating-8.html#post2151765
And here,
http://www.diyaudio.com/forums/planars-exotics/109789-esl-diaphragm-coating-8.html#post2160477
http://www.diyaudio.com/forums/planars-exotics/109789-esl-diaphragm-coating-8.html#post2154390
http://www.diyaudio.com/forums/planars-exotics/109789-esl-diaphragm-coating-8.html#post2154938
As per a discussion I had with Roger Sanders at the time (I made them in 2003), he said to use a PC material that has the highest Dielectric Constant (K) you can get even though it has a lower Dielectric Breakdown rating (volts per mil).
So, I did a lot of research on different ones available at the time but I never did get any PC material of the type I wanted to use and have some more made.
Those panels are/were the only ones of their type ever made to date.
I can say that they did perform incredibly well and you will find most all of my descriptions of experiences with them mostly in that thread.
Sadly they were the experimental guinea pigs for my research of a better design and suffered for it!!! He,he,he,he
There wasn't a whole I could do to improve the design, but just a few things to handle the voltages better.
They did do +110db as measured at 1 meter and lasted some 8 or 9 years for me.
Had I already known what their voltages ratings were, I would still be listening to them today.
But I didn't! 😉
I did make some improvements as I went along, when I got them back working again during the times of that thread after sitting in the closet for 6 or 7 years.
jer 🙂
P.S. Sorry that I have posted those links out of order. 😉
It was a freebie done by a local coater back in 2003 just to prove the concept and he made me a few samples that I had double coated in order to make it work.
So, I only had enough material that surpassed the tests to build one pair of panels.
I picked up a jar of some PC material from a local Habor Freight tool store that I want to try to use to duplicate my original panels.
All I know is that the new stuff I have was made in India but it was only $5 for a 1lb jar of it.
If you do choose to do powder coating don't expect it to work perfectly, as many have tried that route and have had it fail or eventually fail.
But like I said it does make a nice base coat to start with if you can do it cheap enough.
However only my second sample that I had made worked and later I had to re-coat them using clear acrylic.
The very First sample the guy did, he handed it to me rolled up into a tube and when I got it home it miserably failed my High Voltage tests due to micro cracks.
Here is one description and some pictures of when I refurbished those panels, there are many more posts and close ups of them in this thread,
http://www.diyaudio.com/forums/planars-exotics/109789-esl-diaphragm-coating-8.html#post2151765
And here,
http://www.diyaudio.com/forums/planars-exotics/109789-esl-diaphragm-coating-8.html#post2160477
http://www.diyaudio.com/forums/planars-exotics/109789-esl-diaphragm-coating-8.html#post2154390
http://www.diyaudio.com/forums/planars-exotics/109789-esl-diaphragm-coating-8.html#post2154938
As per a discussion I had with Roger Sanders at the time (I made them in 2003), he said to use a PC material that has the highest Dielectric Constant (K) you can get even though it has a lower Dielectric Breakdown rating (volts per mil).
So, I did a lot of research on different ones available at the time but I never did get any PC material of the type I wanted to use and have some more made.
Those panels are/were the only ones of their type ever made to date.
I can say that they did perform incredibly well and you will find most all of my descriptions of experiences with them mostly in that thread.
Sadly they were the experimental guinea pigs for my research of a better design and suffered for it!!! He,he,he,he
There wasn't a whole I could do to improve the design, but just a few things to handle the voltages better.
They did do +110db as measured at 1 meter and lasted some 8 or 9 years for me.
Had I already known what their voltages ratings were, I would still be listening to them today.
But I didn't! 😉
I did make some improvements as I went along, when I got them back working again during the times of that thread after sitting in the closet for 6 or 7 years.
jer 🙂
P.S. Sorry that I have posted those links out of order. 😉
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Hmm, my gut feeling is that if I go to a powder coating business and start talking about dielectric constant they are going to look at me like I am from mars.
I have seen your build with the red stators at the ESL-DIY forum. That is why I started the process of DIY-ESL. Also, we got a 12kV insulation tester at work.
The reason I am asking questions is to learn from others mistakes/Learning process. But I Think it is time to start testing some paint. I didnt like the bad coverage and function of the liquid tape spray that I tried, but I will paint a metal piece with clear coat and see how that goes. Is there a method to get the edges covered?
I have seen your build with the red stators at the ESL-DIY forum. That is why I started the process of DIY-ESL. Also, we got a 12kV insulation tester at work.
The reason I am asking questions is to learn from others mistakes/Learning process. But I Think it is time to start testing some paint. I didnt like the bad coverage and function of the liquid tape spray that I tried, but I will paint a metal piece with clear coat and see how that goes. Is there a method to get the edges covered?
In case you haven't seen it, Here is the thread on how I built my Regulated Variable 0V to 13.8Kv High Voltage supply that I use for testing of dielectric coatings,
http://www.diyaudio.com/forums/plan...tor-insulation-mylar-coating.html#post2848194
and here,
Does anyone have schematics of a varible HV power supply
I have been contemplating on coming up with and presenting a simpler design that would be easier to build for the average DIYer.
I had to do some experimenting to get the thing to work properly without blowing FET's with the toroid cores I was using out of my junk box for the transformers.
It was all new to me at the time and it was a learning process as I was designing and building it.
So I don't have an exact recipe for them yet for it to be easy to duplicate and be foolproof for a First time builder.
The thing runs at about 180Khz or so, so it was a bit tricky to do especially using a 555 timer as its heart, but it does work and has not failed me yet since I have finished it.
It turned out to be very precise, Much much better than I had expected. 😉
It is adjustable to at least a 1v or maybe even .1v resolution or better and does not drift over time!!
I have left it on for days and it never shifts!
Its recovery from an arc discharge is very fast an accurate so that you can read the voltage setting when one occurs.
You can see this by the scope traces of the actual output voltages under such conditions that I have posted.
Even if you shut it down to remove the fault and power it back up it goes back to exactly what it was set to, before the supply was turned off.
jer 🙂
http://www.diyaudio.com/forums/plan...tor-insulation-mylar-coating.html#post2848194
and here,
Does anyone have schematics of a varible HV power supply
I have been contemplating on coming up with and presenting a simpler design that would be easier to build for the average DIYer.
I had to do some experimenting to get the thing to work properly without blowing FET's with the toroid cores I was using out of my junk box for the transformers.
It was all new to me at the time and it was a learning process as I was designing and building it.
So I don't have an exact recipe for them yet for it to be easy to duplicate and be foolproof for a First time builder.
The thing runs at about 180Khz or so, so it was a bit tricky to do especially using a 555 timer as its heart, but it does work and has not failed me yet since I have finished it.
It turned out to be very precise, Much much better than I had expected. 😉
It is adjustable to at least a 1v or maybe even .1v resolution or better and does not drift over time!!
I have left it on for days and it never shifts!
Its recovery from an arc discharge is very fast an accurate so that you can read the voltage setting when one occurs.
You can see this by the scope traces of the actual output voltages under such conditions that I have posted.
Even if you shut it down to remove the fault and power it back up it goes back to exactly what it was set to, before the supply was turned off.
jer 🙂
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I'd like to use epoxy paint (appliance paint - in a rattle can), so I'd be interested in an answer to this question as well.
I think I will try some epoxy paint during the weekend, will post my results. If I have time I will also get some clear coat.
I have read of one using an epoxy paint but I personally have not tried it.
I believe he rolled it on as well and I was surprised that this worked, because rolling would introduce air bubbles embedding them in to the coating and this will weaken the insulating factor.
However, I did use the Epoxy Appliance type paint in a spray can on my very First panels and it was white.
It cured very nicely however it was loaded with Titanium Dioxide (white pigment) and that is how I found out that it conducts at a high voltage.
It worked but I couldn't use any voltages above about 3.5Kv without them arcing!!
As I had already said, Stay Away from the types of paints with the mentioned pigments!!
I have spent a lot of time and money investigating this and trying different types!
Trust me they may work but you won't get the best performance using them.
The best type of coating to use is one with no pigments in it, and/or else a primer that is loaded with talc and has no conductive pigments, and that would be the red ones.
I have found that because of the talc that is in the red primers that they may actually have a higher dielectric breakdown factor.
I have measured this, but I never investigated it any farther than what I have already posted because of the time it takes and wasted materials to make each sample.
Once a sample is tested and a hole is punctured through it the sample is no good anymore and you have to make a whole new one from scratch.
The tests that I did has shown that you can pretty much be sure of at least 1500v per mil of dielectric strength as a safe limit without any punch through of the coating with clear acrylic's.
With a peak of about 1900v per mil at a punch through.
Two samples I did try with just the red primer on them suggested a punch through voltage of about 2100V to 2200V per mil if not a little more.
This was enough for me so I stopped making and testing samples after that and made the wire mesh sample in the thread that I posted the pictures of in order to have proof of concept.
Then I went ahead and made my new TIG rod design using the same process while carefully measuring the thickness of the coating as I went along with a micrometer, since the paint was quite soft until it completely cured.
Curing took about 2 or 3 months and longer before they hardened to be able to not get nicked easily.
Although I did test them about a week after coating them and they surpassed the highest voltage that my supply produces at 13.8Kv even with the ground wire touching them.
The coating thickness is exactly in my projected figure of 8mil to 10mil.
All of that data is verified in the ESDIY thread.
These stator's should withstand any Peak voltages as high as 25Kvp-p between them.
Now, I still haven't put a diaphragm on them, But there is no question that they will work anyhow. 😉
Also Talc has a high Dielectric constant and this is good to.
Do use a primer when you are going to coat bare metal there are many reasons why it is done that way in the First place.
I am very interested in seeing your results and hope to see you get good results from your venture in to this wonderful technology!!
Good Luck!!! 😉
jer 🙂
I believe he rolled it on as well and I was surprised that this worked, because rolling would introduce air bubbles embedding them in to the coating and this will weaken the insulating factor.
However, I did use the Epoxy Appliance type paint in a spray can on my very First panels and it was white.
It cured very nicely however it was loaded with Titanium Dioxide (white pigment) and that is how I found out that it conducts at a high voltage.
It worked but I couldn't use any voltages above about 3.5Kv without them arcing!!
As I had already said, Stay Away from the types of paints with the mentioned pigments!!
I have spent a lot of time and money investigating this and trying different types!
Trust me they may work but you won't get the best performance using them.
The best type of coating to use is one with no pigments in it, and/or else a primer that is loaded with talc and has no conductive pigments, and that would be the red ones.
I have found that because of the talc that is in the red primers that they may actually have a higher dielectric breakdown factor.
I have measured this, but I never investigated it any farther than what I have already posted because of the time it takes and wasted materials to make each sample.
Once a sample is tested and a hole is punctured through it the sample is no good anymore and you have to make a whole new one from scratch.
The tests that I did has shown that you can pretty much be sure of at least 1500v per mil of dielectric strength as a safe limit without any punch through of the coating with clear acrylic's.
With a peak of about 1900v per mil at a punch through.
Two samples I did try with just the red primer on them suggested a punch through voltage of about 2100V to 2200V per mil if not a little more.
This was enough for me so I stopped making and testing samples after that and made the wire mesh sample in the thread that I posted the pictures of in order to have proof of concept.
Then I went ahead and made my new TIG rod design using the same process while carefully measuring the thickness of the coating as I went along with a micrometer, since the paint was quite soft until it completely cured.
Curing took about 2 or 3 months and longer before they hardened to be able to not get nicked easily.
Although I did test them about a week after coating them and they surpassed the highest voltage that my supply produces at 13.8Kv even with the ground wire touching them.
The coating thickness is exactly in my projected figure of 8mil to 10mil.
All of that data is verified in the ESDIY thread.
These stator's should withstand any Peak voltages as high as 25Kvp-p between them.
Now, I still haven't put a diaphragm on them, But there is no question that they will work anyhow. 😉
Also Talc has a high Dielectric constant and this is good to.
Do use a primer when you are going to coat bare metal there are many reasons why it is done that way in the First place.
I am very interested in seeing your results and hope to see you get good results from your venture in to this wonderful technology!!
Good Luck!!! 😉
jer 🙂
I used some epoxi intended for fixing surf boards. Has worked well for other applications. I painted the epoxi on to metal with a brush. I did not use any primer. I dont know if that matters because the epoxi did not spread/float out nicely. There is almost nothing Close to the edges. I tried dipping it too, bud it just doesnt want to stick to the edges. So I am calling failure on this experiment.
I also tried polyester since I had it in the same bag in the basement. That floats out much better. Unfortunately it also gets quit e thick. But perhaps I can apply it in a way that it wont be too thick on the flat surface.
Somewhere in my mind I am thinking that this will end with me buying a bunch of rattle cans of acrylic clear coat...
I also tried polyester since I had it in the same bag in the basement. That floats out much better. Unfortunately it also gets quit e thick. But perhaps I can apply it in a way that it wont be too thick on the flat surface.
Somewhere in my mind I am thinking that this will end with me buying a bunch of rattle cans of acrylic clear coat...
hi.
my stators are coatet with 2 layer of ordinary metal primer (raddle can) then 4 layer of black engine paint (raddel can)from biltema and finaly 4 layer of 2 component polyester resin also from biltema. the polyester is so thin that it float nicely together then applyet from both sites of the stators, before starting the stators must be cleanet very very well for grease and oil, it have worked very well for me for over a 1 year now and i have not notice any artcing at all. just the way i have done it.
for the membrane i have used varmasons waterbased antistatic floor polish.
Ls
my stators are coatet with 2 layer of ordinary metal primer (raddle can) then 4 layer of black engine paint (raddel can)from biltema and finaly 4 layer of 2 component polyester resin also from biltema. the polyester is so thin that it float nicely together then applyet from both sites of the stators, before starting the stators must be cleanet very very well for grease and oil, it have worked very well for me for over a 1 year now and i have not notice any artcing at all. just the way i have done it.
for the membrane i have used varmasons waterbased antistatic floor polish.
Ls
hi again.
ups i forgot, the polyester is applyet with a little foamroller, advice do it outdoors it smell like hell😡
ups i forgot, the polyester is applyet with a little foamroller, advice do it outdoors it smell like hell😡
How high voltages are you running?
I like the polyester too, should try it with some primer first.
I like the polyester too, should try it with some primer first.
As Quoted~ " I tried dipping it too, bud it just doesnt want to stick to the edges, I tried dipping it too, bud it just doesnt want to stick to the edges. So I am calling failure on this experiment. "
As I has already mentioned there really is a reason to use a Primer when you are coating with paints!!
Look at these pictures,
http://www.diyaudio.com/forums/plan...tric-coatings-fact-fiction-2.html#post2902754
http://www.diyaudio.com/forums/plan...tric-coatings-fact-fiction-2.html#post2893839
You want to avoid any sharp edges or at least get them covered at all costs!!
A sharp point from my wire mesh that wasn't properly insulated was the cause of failure of my best panels when they burned up.
There was no fixing them I tried.....Many times over!!!
There are close ups of this somewhere in these threads but I don't have the links of them handy at this time.
Once you burn the coating, the chance of fixing it is very slim!
But, It is not so bad when using a metal panel.
Although you do have to strip everything from the bad spot down to bare metal and re-coat that area.
It is advisable to test the integrity of your coating before mounting the diaphragm using your bias supply and stepup transformers mocked up while it is operating with your amplifier as it would be in a normal situation, but without the diaphragm.
Especially if you are planning on using double sided sticky tape to mount them.
In the long run it is not the bias voltage you have to worry about.
It is the voltage that is coming out of the step-up transformers that cause most of the failures, as it can be 4 to 8 times or more than that of the bias voltage.
Especially at the highest frequency's is when the failures are more frequent and cause the most stress on the coating!!
Sorry, I can not stress this enough!!!
I have seen too many not heed by these simple steps only to find themselves starting all over anyway.
FWIW
jer 🙂
P.S. It is all Good, I learned to hard way myself and tried everything under the sun that was available!!
Only to find they they are much more simpler and cheaper to build than what I thought !! He,he,he,he 😉
I could have built 15 or 20 pairs of my little ones for less than $10 a pair for the money I spent on R&D !!! 🙂
As I has already mentioned there really is a reason to use a Primer when you are coating with paints!!
Look at these pictures,
http://www.diyaudio.com/forums/plan...tric-coatings-fact-fiction-2.html#post2902754
http://www.diyaudio.com/forums/plan...tric-coatings-fact-fiction-2.html#post2893839
You want to avoid any sharp edges or at least get them covered at all costs!!
A sharp point from my wire mesh that wasn't properly insulated was the cause of failure of my best panels when they burned up.
There was no fixing them I tried.....Many times over!!!
There are close ups of this somewhere in these threads but I don't have the links of them handy at this time.
Once you burn the coating, the chance of fixing it is very slim!
But, It is not so bad when using a metal panel.
Although you do have to strip everything from the bad spot down to bare metal and re-coat that area.
It is advisable to test the integrity of your coating before mounting the diaphragm using your bias supply and stepup transformers mocked up while it is operating with your amplifier as it would be in a normal situation, but without the diaphragm.
Especially if you are planning on using double sided sticky tape to mount them.
In the long run it is not the bias voltage you have to worry about.
It is the voltage that is coming out of the step-up transformers that cause most of the failures, as it can be 4 to 8 times or more than that of the bias voltage.
Especially at the highest frequency's is when the failures are more frequent and cause the most stress on the coating!!
Sorry, I can not stress this enough!!!
I have seen too many not heed by these simple steps only to find themselves starting all over anyway.
FWIW
jer 🙂
P.S. It is all Good, I learned to hard way myself and tried everything under the sun that was available!!
Only to find they they are much more simpler and cheaper to build than what I thought !! He,he,he,he 😉
I could have built 15 or 20 pairs of my little ones for less than $10 a pair for the money I spent on R&D !!! 🙂
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What I'm considering using is this:
Amazon.com: Krylon 3206 Black Appliance Epoxy - 12 oz. Aerosol: Automotive
I've used it on speaker baffles and it builds up nicely and is fairly easy to get a consistent finish (assuming the surface prep has been done well).
So, it sounds like primer before and clearcoat after are in order. In that case, I suppose I wouldn't need more than enough coats of the epoxy to get a good consistent black color.
Amazon.com: Krylon 3206 Black Appliance Epoxy - 12 oz. Aerosol: Automotive
I've used it on speaker baffles and it builds up nicely and is fairly easy to get a consistent finish (assuming the surface prep has been done well).
So, it sounds like primer before and clearcoat after are in order. In that case, I suppose I wouldn't need more than enough coats of the epoxy to get a good consistent black color.
I have not tried the Black type, So I can't tell you what its performance is.
The stuff I used was white and I found out when made then, and 7 years later after I made them, that it conducts at higher voltages.
This is because it took me that long to get back into it and finally have a proper drive system to reach such voltages and also by building my variable HV supply to test with.
Keep in mind that a panel with a large surface are doesn't need as high of a bias voltage I use to preform either, but evey little bit helps.
On the otherhand the driving voltages out of the transformer are the same at 4 to 10Kv peak of you are running them hard.
Even this can be quite loud for a large panel with only 2.5-4Kv of bias!!
IMHO it is to costly if it is just going to be used as a color coat.
That very same stuff cost a lot in the stores here too.
I can get a large can of 2Xclear for half of the price!!
The 2X clears are quite thick but you get 2 to 3 times the material for the same price as the normal basic thin stuff.
I basically don't trust any paints with pigments in them, at least for a final coat.
I have read however that the Black Types are not as bad because the Carbon Black molecules are supposedly encapsulated, but I have not tested them as of yet for a top coat.
Like I said if you want to use a color coat then all you need is one thin coat of the color of your choice and then build the rest up with clear.
Clear has no pigments and you are then guaranteed a good clean non conductive insulative coating, as long as you put it on wet and let each layer cure a bit before the next application.
Just like it says in the instructions on the can, it is good to add your coats before each layer is completely cured.
This helps with the bonding of each layer that is added to the previous layer.
This will assure that no bubbles are formed from out gassing as well during the curing process.
I still have the wire mesh sample that I made in the pictures and it is completely flexible.
I get it out every once in a while to test it, and it has yet to form any microcracks and fail an HV tests just like in the pictures.
And, It has been about over 2 years now since I made it.
Remember that it is an epoxy type paint and the two different types may or may not bond together well from what I have read, again I have not tested this yet.
Just because the Epoxy type paints cure very hard, this does not mean that they will have good dielectric properties as well.
Also since they are much harder when they have cured they could possibly crack much easier when the stator is flexed during assembly.
You cannot see microcracks with the naked eye, You will only find these after some voltage has been applied to the stator.
jer 🙂
P.S. The best price I have on 2X clear here in the States is at Menards for $3.37 a can and I think it is on sale right now for even less at $2.98!!
Opps the picture I got was semi gloss but usually they are on sale at the same time.
I have some Semi gloss that I have been wanting to test as that stuff is loaded with Silicon Dioxide(glass powder)!! 😉
Yes, I just found the same in plain clear and it too is on sale, your in luck!! 😀
The stuff I used was white and I found out when made then, and 7 years later after I made them, that it conducts at higher voltages.
This is because it took me that long to get back into it and finally have a proper drive system to reach such voltages and also by building my variable HV supply to test with.
Keep in mind that a panel with a large surface are doesn't need as high of a bias voltage I use to preform either, but evey little bit helps.
On the otherhand the driving voltages out of the transformer are the same at 4 to 10Kv peak of you are running them hard.
Even this can be quite loud for a large panel with only 2.5-4Kv of bias!!
IMHO it is to costly if it is just going to be used as a color coat.
That very same stuff cost a lot in the stores here too.
I can get a large can of 2Xclear for half of the price!!
The 2X clears are quite thick but you get 2 to 3 times the material for the same price as the normal basic thin stuff.
I basically don't trust any paints with pigments in them, at least for a final coat.
I have read however that the Black Types are not as bad because the Carbon Black molecules are supposedly encapsulated, but I have not tested them as of yet for a top coat.
Like I said if you want to use a color coat then all you need is one thin coat of the color of your choice and then build the rest up with clear.
Clear has no pigments and you are then guaranteed a good clean non conductive insulative coating, as long as you put it on wet and let each layer cure a bit before the next application.
Just like it says in the instructions on the can, it is good to add your coats before each layer is completely cured.
This helps with the bonding of each layer that is added to the previous layer.
This will assure that no bubbles are formed from out gassing as well during the curing process.
I still have the wire mesh sample that I made in the pictures and it is completely flexible.
I get it out every once in a while to test it, and it has yet to form any microcracks and fail an HV tests just like in the pictures.
And, It has been about over 2 years now since I made it.
Remember that it is an epoxy type paint and the two different types may or may not bond together well from what I have read, again I have not tested this yet.
Just because the Epoxy type paints cure very hard, this does not mean that they will have good dielectric properties as well.
Also since they are much harder when they have cured they could possibly crack much easier when the stator is flexed during assembly.
You cannot see microcracks with the naked eye, You will only find these after some voltage has been applied to the stator.
jer 🙂
P.S. The best price I have on 2X clear here in the States is at Menards for $3.37 a can and I think it is on sale right now for even less at $2.98!!
Opps the picture I got was semi gloss but usually they are on sale at the same time.
I have some Semi gloss that I have been wanting to test as that stuff is loaded with Silicon Dioxide(glass powder)!! 😉
Yes, I just found the same in plain clear and it too is on sale, your in luck!! 😀
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Hi,
I´d say stay away from all greyish and black laquers, apart from maybe a very thin layer for colouration/optics.
This layer needs to be coated and encapsulated also.
Even if manufacturers spec high flashover values for black stuff I wouldn´t rely on that, as the conditions found in an ESL differ by far from the test procedures of the manufacturers. A value measured on a plain surface under DC-conditions will be at least 5 times higher than a pinpoint at 10kHz.
Also I haven´t seen manufacturers spec the longtime flashover tresholds.
As a material ages under HV influence, tiny carbonized spots within the coating develop. Those spots grow into tracks looking a bit like a tiny tree (where they get their name from).
When the tree has grown so far it reaches the surface of the coating breakdown occurs.
It is of course not helpful to supply for the initial spots by using a coating containing any form of carbon or a material that easily carbonizes.
jau
Calvin
I´d say stay away from all greyish and black laquers, apart from maybe a very thin layer for colouration/optics.
This layer needs to be coated and encapsulated also.
Even if manufacturers spec high flashover values for black stuff I wouldn´t rely on that, as the conditions found in an ESL differ by far from the test procedures of the manufacturers. A value measured on a plain surface under DC-conditions will be at least 5 times higher than a pinpoint at 10kHz.
Also I haven´t seen manufacturers spec the longtime flashover tresholds.
As a material ages under HV influence, tiny carbonized spots within the coating develop. Those spots grow into tracks looking a bit like a tiny tree (where they get their name from).
When the tree has grown so far it reaches the surface of the coating breakdown occurs.
It is of course not helpful to supply for the initial spots by using a coating containing any form of carbon or a material that easily carbonizes.
jau
Calvin
What then are the best materials and/or best practices for insulating the stators when there is a preference against the look of bare (clearcoated) metal?
Hi,
well I´d say use a 3 layer structure.
1st layer is a thick primer or base coat, which could be applied wet, e.g. a clear acrylic laquer, or the red stuff mentioned earlier.
The layer could also be applied as powder coat, e.g a pure white Nylon-derivative, or anything else suitable as primer with sufficient flashover treshold, suitably high dielectric constant and(!) the ability for a thick build-up around sharp edgess.
Besides its good electrical properties Nylon is one of the few powder coats that allows for small radii of constant thickness.
The second layer is a thin layer of colour just for optics.
The third layer is a thick top coatand may again be a clear transparent coating from high gloss acrylics or an PU-laquer.
I never managed to get truely smooth surfaces using water based acrylics.
It always dried out too fast.
The solvent based PU cures slower, giving perfectly smooth, pinhole free and highly durable surfaces (its used as top coat for boats and stairs, so it can take real ruff handling).
jauu
Calvin
well I´d say use a 3 layer structure.
1st layer is a thick primer or base coat, which could be applied wet, e.g. a clear acrylic laquer, or the red stuff mentioned earlier.
The layer could also be applied as powder coat, e.g a pure white Nylon-derivative, or anything else suitable as primer with sufficient flashover treshold, suitably high dielectric constant and(!) the ability for a thick build-up around sharp edgess.
Besides its good electrical properties Nylon is one of the few powder coats that allows for small radii of constant thickness.
The second layer is a thin layer of colour just for optics.
The third layer is a thick top coatand may again be a clear transparent coating from high gloss acrylics or an PU-laquer.
I never managed to get truely smooth surfaces using water based acrylics.
It always dried out too fast.
The solvent based PU cures slower, giving perfectly smooth, pinhole free and highly durable surfaces (its used as top coat for boats and stairs, so it can take real ruff handling).
jauu
Calvin
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