Secondary coating
omegalabs, Sat Jan 24 2009, 07:14PMHi! I have a question. I use nitro lacquer (I don't know how it's called in english) for secondary coil, but it charges up electrostatically and produces sparks on the secondary surface, on high power. As I see, some people use polyurethane coating, but I can't find here in Hungary, or on ebay. Can someone offer me a good insulator coating?      Â
Thanks.
Re: Secondary coating
Mads Barnkob, Sat Jan 24 2009, 07:41PM
You are getting what we call "racing sparks" and this will happen to any secondary that is too tight coupled to the primary, or have a too thin varnish.
How many layers of varnish did you give your secondary? and what kind of tesla coil is it operating in?
Mads Barnkob, Sat Jan 24 2009, 07:41PM
You are getting what we call "racing sparks" and this will happen to any secondary that is too tight coupled to the primary, or have a too thin varnish.
How many layers of varnish did you give your secondary? and what kind of tesla coil is it operating in?
Re: Secondary coating
Arcstarter, Sat Jan 24 2009, 10:38PM
Hello, what Dr. Spark uses is Minwax fast-drying clear-gloss superior durability polyurethane. I use it too, and it work very well. It is quite cheap, really.
I have used it on my new coil, and it is easy to apply and dries enough for the next coat in 30 minutes to an hour. That is me coating it with it. It is near the exact same polyurethane, but mine says clear gloss, and the one on ebay is clear semi-gloss. I am not sure what the difference is.
Hope it helps.
Arcstarter, Sat Jan 24 2009, 10:38PM
Hello, what Dr. Spark uses is Minwax fast-drying clear-gloss superior durability polyurethane. I use it too, and it work very well. It is quite cheap, really.
I have used it on my new coil, and it is easy to apply and dries enough for the next coat in 30 minutes to an hour.
That is me coating it with it. It is near the exact same polyurethane, but mine says clear gloss, and the one on ebay is clear semi-gloss. I am not sure what the difference is.Hope it helps.
Re: Secondary coating
omegalabs, Sun Jan 25 2009, 12:57PM
Yes, I know the coupling is matter, but I think the nitro coating is still the problem. I used this coating on several secondary coils, with 1 or 2 layer, but every secondary produces the same racing sparks on medium coupling. I realize this just now, yersterday.
A fatally secondary spark melt the wire between two windings, just before a show, where was 400 people. Fortunately I improved the secondary in time (that was in september 2008). This is my 11,8 inch (300mm) coil :
I working now on a 3 phase 12kW 12MOT powered DC coil, and I want to sure, that the secondary is insulated well.
omegalabs, Sun Jan 25 2009, 12:57PM
MadsKaizer wrote ...
You are getting what we call "racing sparks" and this will happen to any secondary that is too tight coupled to the primary, or have a too thin varnish.
How many layers of varnish did you give your secondary? and what kind of tesla coil is it operating in?
You are getting what we call "racing sparks" and this will happen to any secondary that is too tight coupled to the primary, or have a too thin varnish.
How many layers of varnish did you give your secondary? and what kind of tesla coil is it operating in?
Yes, I know the coupling is matter, but I think the nitro coating is still the problem. I used this coating on several secondary coils, with 1 or 2 layer, but every secondary produces the same racing sparks on medium coupling. I realize this just now, yersterday.
A fatally secondary spark melt the wire between two windings, just before a show, where was 400 people. Fortunately I improved the secondary in time (that was in september 2008). This is my 11,8 inch (300mm) coil :
I working now on a 3 phase 12kW 12MOT powered DC coil, and I want to sure, that the secondary is insulated well.
Re: Secondary coating
omegalabs, Sun Jan 25 2009, 01:01PM
Thanks, this is really cheap, but the shipping is 30$
I think I buy one soon.
I meaning about, that can I use this coating on my original nitro coating? Or I must clear the secondary before I apply the new polyurethane coating?
omegalabs, Sun Jan 25 2009, 01:01PM
Arcstarter wrote ...
Hello, what Dr. Spark uses is Minwax fast-drying clear-gloss superior durability polyurethane. I use it too, and it work very well. It is quite cheap, really.
I have used it on my new coil, and it is easy to apply and dries enough for the next coat in 30 minutes to an hour. That is me coating it with it. It is near the exact same polyurethane, but mine says clear gloss, and the one on ebay is clear semi-gloss. I am not sure what the difference is.
Hope it helps.
Hello, what Dr. Spark uses is Minwax fast-drying clear-gloss superior durability polyurethane. I use it too, and it work very well. It is quite cheap, really.
I have used it on my new coil, and it is easy to apply and dries enough for the next coat in 30 minutes to an hour.
That is me coating it with it. It is near the exact same polyurethane, but mine says clear gloss, and the one on ebay is clear semi-gloss. I am not sure what the difference is.Hope it helps.
Thanks, this is really cheap, but the shipping is 30$
I think I buy one soon. I meaning about, that can I use this coating on my original nitro coating? Or I must clear the secondary before I apply the new polyurethane coating?
Re: Secondary coating
MOT_man, Sun Jan 25 2009, 05:36PM
Nitro lacquer depending upon its age can be slightly acidic and isn't recommended for insulating purposes at all. Polyurethane or Varathane brand varnish can be found in hardware stores internationally.
MOT_man, Sun Jan 25 2009, 05:36PM
omegalabs wrote ...
Hi! I have a question. I use nitro lacquer (I don't know how it's called in english) for secondary coil, but it charges up electrostatically and produces sparks on the secondary surface, on high power. As I see, some people use polyurethane coating, but I can't find here in Hungary, or on ebay. Can someone offer me a good insulator coating?      Â
Thanks.
Hi! I have a question. I use nitro lacquer (I don't know how it's called in english) for secondary coil, but it charges up electrostatically and produces sparks on the secondary surface, on high power. As I see, some people use polyurethane coating, but I can't find here in Hungary, or on ebay. Can someone offer me a good insulator coating?      Â
Thanks.
Nitro lacquer depending upon its age can be slightly acidic and isn't recommended for insulating purposes at all. Polyurethane or Varathane brand varnish can be found in hardware stores internationally.
Re: Secondary coating
Dr. Drone, Sun Jan 25 2009, 08:00PM
Dr. Drone, Sun Jan 25 2009, 08:00PM
Re: Secondary coating
omegalabs, Sun Jan 25 2009, 10:07PM
It's work well on small coils.. but for medium and big sized coils it's not god. (the nitro)
omegalabs, Sun Jan 25 2009, 10:07PM
MOT_man wrote ...
Nitro lacquer depending upon its age can be slightly acidic and isn't recommended for insulating purposes at all. Polyurethane or Varathane brand varnish can be found in hardware stores internationally.
omegalabs wrote ...
Hi! I have a question. I use nitro lacquer (I don't know how it's called in english) for secondary coil, but it charges up electrostatically and produces sparks on the secondary surface, on high power. As I see, some people use polyurethane coating, but I can't find here in Hungary, or on ebay. Can someone offer me a good insulator coating?      Â
Thanks.
Hi! I have a question. I use nitro lacquer (I don't know how it's called in english) for secondary coil, but it charges up electrostatically and produces sparks on the secondary surface, on high power. As I see, some people use polyurethane coating, but I can't find here in Hungary, or on ebay. Can someone offer me a good insulator coating?      Â
Thanks.
Nitro lacquer depending upon its age can be slightly acidic and isn't recommended for insulating purposes at all. Polyurethane or Varathane brand varnish can be found in hardware stores internationally.
It's work well on small coils.. but for medium and big sized coils it's not god. (the nitro)
Re: Secondary coating
omegalabs, Sun Jan 25 2009, 10:18PM
Is water based polyurethane good too? Many urethane lacquer is used for parquet coating that you can get in the shops here, and most of them are water based. I wasn't sure if water based coatings work well for insulation purpuses.
omegalabs, Sun Jan 25 2009, 10:18PM
Dr. Spark wrote ...
You may be able to give the secondary a light sanding and cover with polyurethane. This issue possibly here is the two do not get along or the polyurethane will not stick. Sand a little spot ( 800 grit wet/dry) on perhaps the bottom of secondary (where no one will see and no wire) with polyurethane and then wait a week. Look at the spot a week later under good light for crakes, fractures, or just anything that would make the first coating worse. Then scratch with fingernail to see if it holds on.
You can use any polyurethane; just call around at wood restore shops, furniture shops etc as someone has it.
Polyurethane is a good insulator and if you look on insulation charts it is high on the list, used in sheets in very high end x-ray transformers.
Have been reviewing a lot of interest in coatings, as there are a lot of coating that work well and a lot that do not. Maybe we can start a post on “Secondary Coatings†with pictures and videos that we can add/refer to when needed.
Cheers,
Ch
omegalabs wrote ...
I meaning about, that can I use this coating on my original nitro coating? Or I must clear the secondary before I apply the new polyurethane coating?
I meaning about, that can I use this coating on my original nitro coating? Or I must clear the secondary before I apply the new polyurethane coating?
You may be able to give the secondary a light sanding and cover with polyurethane. This issue possibly here is the two do not get along or the polyurethane will not stick. Sand a little spot ( 800 grit wet/dry) on perhaps the bottom of secondary (where no one will see and no wire) with polyurethane and then wait a week. Look at the spot a week later under good light for crakes, fractures, or just anything that would make the first coating worse. Then scratch with fingernail to see if it holds on.
You can use any polyurethane; just call around at wood restore shops, furniture shops etc as someone has it.
Polyurethane is a good insulator and if you look on insulation charts it is high on the list, used in sheets in very high end x-ray transformers.
Have been reviewing a lot of interest in coatings, as there are a lot of coating that work well and a lot that do not. Maybe we can start a post on “Secondary Coatings†with pictures and videos that we can add/refer to when needed.
Cheers,
Ch
Is water based polyurethane good too? Many urethane lacquer is used for parquet coating that you can get in the shops here, and most of them are water based. I wasn't sure if water based coatings work well for insulation purpuses.
Re: Secondary coating
Andyman, Sun Jan 25 2009, 11:35PM
I'm not sure if it would really matter. The base evaporates either way, if I remember. Water base seems to cure much faster.
Andyman, Sun Jan 25 2009, 11:35PM
I'm not sure if it would really matter. The base evaporates either way, if I remember. Water base seems to cure much faster.
Re: Secondary coating
omegalabs, Mon Jan 26 2009, 06:03PM
My friend show me this spray:
I think this is a helpful lacquer, with a dielectric strenght of 48kV/mm.
omegalabs, Mon Jan 26 2009, 06:03PM
My friend show me this spray:
I think this is a helpful lacquer, with a dielectric strenght of 48kV/mm.
Re: Secondary coating
Herr Zapp, Mon Jan 26 2009, 06:51PM
omegalabs -
Any insulating coating applied to a Tesla coil secondary is likely to acquire an electrostatic charge during coil operation, and hold this charge long after the coil has stopped running. Even with coils that do not have a coating over the windings, the insulating varnish on the magnet wire itself can acquire a charge, as can the coil form, especially if it is plastic. I have received many good jolts when removing my 6" X 30" secondary from my coil after operation, and the secondary can deliver at least 3-4 good pops several minutes apart, depending on how dry the air is.
Nitrocellulose lacquer is a clear finish usually used on wooden musical instruments, and there's no reason I can think of why it shouldn't work well as a secondary coating. Your secondary will still retain an electrostatic charge if you overcoat the nitrocellulose lacquer with polyurethane, or any other insulating coating.
After building a number of secondary coils and coating them with many coats of conventional solvent-based varnish, I switched to clear 2-part epoxy resin, and have now used this material for almost 10 years. I'm firmly convinced that it is the best material to use, from the standpoint of appearance, improved resistance to secondary arcing or insulation breakdown, mechanical protection of the windings, and ease of application. Correctly applied, one coat of epoxy can give a coating thickness of .020" (.5mm) or greater, and gives a perfectly glass-smooth surface finish.
Here is a write-up on the application process I use. Note that it is essential to have some sort of motorized fixture to mount the coil on so it can be rotated at a slow speed for several hours while the epoxy cures.
Herr Zapp
Herr Zapp, Mon Jan 26 2009, 06:51PM
omegalabs -
Any insulating coating applied to a Tesla coil secondary is likely to acquire an electrostatic charge during coil operation, and hold this charge long after the coil has stopped running. Even with coils that do not have a coating over the windings, the insulating varnish on the magnet wire itself can acquire a charge, as can the coil form, especially if it is plastic. I have received many good jolts when removing my 6" X 30" secondary from my coil after operation, and the secondary can deliver at least 3-4 good pops several minutes apart, depending on how dry the air is.
Nitrocellulose lacquer is a clear finish usually used on wooden musical instruments, and there's no reason I can think of why it shouldn't work well as a secondary coating. Your secondary will still retain an electrostatic charge if you overcoat the nitrocellulose lacquer with polyurethane, or any other insulating coating.
After building a number of secondary coils and coating them with many coats of conventional solvent-based varnish, I switched to clear 2-part epoxy resin, and have now used this material for almost 10 years. I'm firmly convinced that it is the best material to use, from the standpoint of appearance, improved resistance to secondary arcing or insulation breakdown, mechanical protection of the windings, and ease of application. Correctly applied, one coat of epoxy can give a coating thickness of .020" (.5mm) or greater, and gives a perfectly glass-smooth surface finish.
Here is a write-up on the application process I use. Note that it is essential to have some sort of motorized fixture to mount the coil on so it can be rotated at a slow speed for several hours while the epoxy cures.
Herr Zapp
Re: Secondary coating
Tom540, Mon Jan 26 2009, 10:35PM
Water based looks nice dries fast but is not as durable. If you have a heat lamp you could almost re coat it every our or even less. It gets ugly after a few years and can be peeled off. its good for quickie coils or test secondaries but if you want something nice that will last don't use it.
Non water based stuff like varnish, varathane is good middle ground stuff. There's a ton of different kinds. It wont last forever either and needs multiple coats. But is decent.
Furniture epoxy is the best. I use it all the time. It needs one coat and after 3 days is 100% dry. It is super durable and looks nicer than the other three with less effort. It's also pretty water proof as far as I've seen. I coated a homemade coaster with it. The water has had no effect on it so far. There are some places in my garage where ive dripped it on the floor and the spots arent even scratched much. Only bad thing is its more expensive, but then again you only need one coat which is equal to 60 coats of varnish.
Tom540, Mon Jan 26 2009, 10:35PM
Water based looks nice dries fast but is not as durable. If you have a heat lamp you could almost re coat it every our or even less. It gets ugly after a few years and can be peeled off. its good for quickie coils or test secondaries but if you want something nice that will last don't use it.
Non water based stuff like varnish, varathane is good middle ground stuff. There's a ton of different kinds. It wont last forever either and needs multiple coats. But is decent.
Furniture epoxy is the best. I use it all the time. It needs one coat and after 3 days is 100% dry. It is super durable and looks nicer than the other three with less effort. It's also pretty water proof as far as I've seen. I coated a homemade coaster with it. The water has had no effect on it so far. There are some places in my garage where ive dripped it on the floor and the spots arent even scratched much. Only bad thing is its more expensive, but then again you only need one coat which is equal to 60 coats of varnish.
Re: Secondary coating
Herr Zapp, Tue Jan 27 2009, 06:37PM
OOPS -
The .pdf file attachment with the detailed procedure for applying epoxy resin to a secondary coil somehow got dropped from my previous post. Here it is again:
Herr Zapp
]using_2- part_epoxy_resin_for_coating_tesla_coil_secondary. pdf.pdf[/file]
Herr Zapp, Tue Jan 27 2009, 06:37PM
OOPS -
The .pdf file attachment with the detailed procedure for applying epoxy resin to a secondary coil somehow got dropped from my previous post. Here it is again:
Herr Zapp
]using_2- part_epoxy_resin_for_coating_tesla_coil_secondary. pdf.pdf[/file]
Re: Secondary coating
Mathias, Wed Jan 28 2009, 10:57AM
Hello :P
Well I found a great replacement for that minwax stuff here in hungary , its called bona mega 100% polyurethene water based (4200 ft /1L) . Works and looks great. If used as instucted :)
Btw dont use aerosol type coatings the propellent gas gets traped under the coat and when that begins to dry the miniture bubbles "expand"
(or just case of another factor, becase i sprayed the stuff on outside in the cold , later on (when the smell was gone :P) i brought it inside after some hours the bubbles appeared)
Mathias, Wed Jan 28 2009, 10:57AM
Hello :P
Well I found a great replacement for that minwax stuff here in hungary , its called bona mega 100% polyurethene water based (4200 ft /1L) . Works and looks great. If used as instucted :)
Btw dont use aerosol type coatings the propellent gas gets traped under the coat and when that begins to dry the miniture bubbles "expand"
(or just case of another factor, becase i sprayed the stuff on outside in the cold , later on (when the smell was gone :P) i brought it inside after some hours the bubbles appeared)
Re: Secondary coating
omegalabs, Wed Jan 28 2009, 06:17PM
This shop is just near my scool :) . I have searched for epoxy but I found only expensive ones.
Now, the final question. Is this lacquer good, or should I keep trying to find a good epoxy resin?
omegalabs, Wed Jan 28 2009, 06:17PM
Mathias wrote ...
Hello :P
Well I found a great replacement for that minwax stuff here in hungary , its called bona mega 100% polyurethene water based (4200 ft /1L) . Works and looks great. If used as instucted :)
Btw dont use aerosol type coatings the propellent gas gets traped under the coat and when that begins to dry the miniture bubbles "expand"
(or just case of another factor, becase i sprayed the stuff on outside in the cold , later on (when the smell was gone :P) i brought it inside after some hours the bubbles appeared)
Hello :P
Well I found a great replacement for that minwax stuff here in hungary , its called bona mega 100% polyurethene water based (4200 ft /1L) . Works and looks great. If used as instucted :)
Btw dont use aerosol type coatings the propellent gas gets traped under the coat and when that begins to dry the miniture bubbles "expand"
(or just case of another factor, becase i sprayed the stuff on outside in the cold , later on (when the smell was gone :P) i brought it inside after some hours the bubbles appeared)
This shop is just near my scool :) . I have searched for epoxy but I found only expensive ones.
Now, the final question. Is this lacquer good, or should I keep trying to find a good epoxy resin?
Re: Secondary coating
Herr Zapp, Wed Jan 28 2009, 10:53PM
omegalabs -
Glyptal Inc manufactures a wide range of inductrial paints and coatings, including several nitrocellulose lacquers that are advertised as having "high dielectric strength and arc resistance". See Industrial Topcoats, types 7600 and 2496 at:
So, generally speaking, there is nothing to indicate that your nitrocellulose lacquer be unsuitable for a overcoating secondary coil.
Just finish building your coil, and fire it up. I don't think the secondary coating will be a problem.
Regards,
Herr Zapp
Herr Zapp, Wed Jan 28 2009, 10:53PM
omegalabs -
Glyptal Inc manufactures a wide range of inductrial paints and coatings, including several nitrocellulose lacquers that are advertised as having "high dielectric strength and arc resistance". See Industrial Topcoats, types 7600 and 2496 at:
So, generally speaking, there is nothing to indicate that your nitrocellulose lacquer be unsuitable for a overcoating secondary coil.
Just finish building your coil, and fire it up. I don't think the secondary coating will be a problem.
Regards,
Herr Zapp
Re: Secondary coating
MOT_man, Thu Jan 29 2009, 07:01AM
Nitro lacquer is pretty brittle stuff when dry. Over time it will flake off as it become acidic in the presence of UV light. This is why wood workers prefer polyurethane finishes as they are flexible and have better bonding properties.
MOT_man, Thu Jan 29 2009, 07:01AM
Nitro lacquer is pretty brittle stuff when dry. Over time it will flake off as it become acidic in the presence of UV light. This is why wood workers prefer polyurethane finishes as they are flexible and have better bonding properties.
Re: Secondary coating
Herr Zapp, Thu Jan 29 2009, 05:45PM
MOT man -
Can you provide a link to your source of information for the "becomes acidic in the presence of UV light" statement, as applicable to nitrocellulose lacquer coatings?
Thanks!
Herr Zapp
Herr Zapp, Thu Jan 29 2009, 05:45PM
MOT man -
Can you provide a link to your source of information for the "becomes acidic in the presence of UV light" statement, as applicable to nitrocellulose lacquer coatings?
Thanks!
Herr Zapp
Re: Secondary coating
MOT_man, Fri Jan 30 2009, 07:49AM
Stanford University Press -
"nitrocellulose, an ingredient found in polishes & lacquers that turns yellow when exposed to UV and becomes brittle"
R. Fairfield - Int. Woodworker Association
"UV exposure doesn't do much for a nitrocellulose lacquer except make it turn an amber color and become brittle."
PCRC
"Nitrocellulose lacquers are notorious for yellowing, if at all possible you may want to consider using a cellulose acetate butyrate (CAB) acrylic blend. These types of lacquers have been used in the automotive paint industry for many, many years with minimal color change."
Wood Working.com
"By itself, nitrocellulose is very brittle and very hard."
So from all the information I've gathered - and of course speaking with local paint shops and Industrial Transformer winding shops - the verdict is out. Nitrocellulose lacquer works well when it is combined with other Alkyds. By itself as a pure lacquer it is extremely prone to yellowing in the presence of UV light - this photochemical reaction also effects the strength and flexibility of the lacquer as well. The nitrate breaks down chemically in the varnish due to oxidation. The oxidation process - produces an acidic release in the varnish. This is why Polyurethane is a far better product - it isn't nearly as inflexible or prone to photochemical breakdown as NC. If you would like to speak with General Paint, CANADA or Cloverdale paints, CANADA they can verify this information too.
I wouldn't use straight Nitro lacquer on my coil. If it was combined with some other Alkyd then - possibly.
MOT_man, Fri Jan 30 2009, 07:49AM
Stanford University Press -
"nitrocellulose, an ingredient found in polishes & lacquers that turns yellow when exposed to UV and becomes brittle"
R. Fairfield - Int. Woodworker Association
"UV exposure doesn't do much for a nitrocellulose lacquer except make it turn an amber color and become brittle."
PCRC
"Nitrocellulose lacquers are notorious for yellowing, if at all possible you may want to consider using a cellulose acetate butyrate (CAB) acrylic blend. These types of lacquers have been used in the automotive paint industry for many, many years with minimal color change."
Wood Working.com
"By itself, nitrocellulose is very brittle and very hard."
So from all the information I've gathered - and of course speaking with local paint shops and Industrial Transformer winding shops - the verdict is out. Nitrocellulose lacquer works well when it is combined with other Alkyds. By itself as a pure lacquer it is extremely prone to yellowing in the presence of UV light - this photochemical reaction also effects the strength and flexibility of the lacquer as well. The nitrate breaks down chemically in the varnish due to oxidation. The oxidation process - produces an acidic release in the varnish. This is why Polyurethane is a far better product - it isn't nearly as inflexible or prone to photochemical breakdown as NC. If you would like to speak with General Paint, CANADA or Cloverdale paints, CANADA they can verify this information too.
I wouldn't use straight Nitro lacquer on my coil. If it was combined with some other Alkyd then - possibly.
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