HELP What plastics best resist lacquer thinner?

[recordman]

HELP:

What plastics would be most resistant to melting / warping, if a (rigid) sheet of that plastic between 1/16" and 1/8" thick was coated on both sides with a layer of thickened nitrocellulose LACQUER mixture, and left slowly rotating in a vertical position to dry?

From what I've seen, lacquer thinner tends to melt plastics; I'm wondering what plastics would be most resistant, to buy sheets online & try. I was thinking maybe polycarbonate?...

I want to start making less-expensive phonograph record music blank discs. They were traditionally made with a metal base; I'd like to try plastic, since it's easier to cut into disc shapes.

Thanks,
- recordman

 

[patprimmer]

Polycarbonate is about the worst possible choice you could make.

Do you need the lacquer to have good adhesion to the plastic. If so some attack by the solvent will actually help.

PVC is generally a good compromise in that it will dissolve in the solvent but is less liable to solvent stress crack due to exposure to solvent.

Materials resistant to attack are the materials used in fuel systems and spray guns. From memory, these are nylons, polyesters and acetal. Polyethylene and polyproplene can also be used but tend to swell.

Regards
Pat
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[Compositepro]

There are probably good reasons that metal is used. Thin sheets are very prone to warping due to even small stresses. All plastics will experience more stress than metal due to solvent exposure and they are far less stiff to resist these stresses. Aluminum is pretty easy to cut and not very expensive.

 

[recordman]

Thanks for the responses. I've ordered PVC sheets 1/16 & 1/8 to experiment with. (And, conveniently enough, also recently had a record pressing plant press up totally blank, un-grooved 7-inch and 12-inch PVC vinyl records, so will try coating a couple of those too.)

I found while cleaning up, a table-mounted jigsaw, and will be seeking out a metal-rated blade which could cut nylon & aluminum, and will try those too.

Many thanks

 

[patprimmer]

I doubt the lacquer will stick to nylon. Also nylon expands and contracts as it absorbs or loses moisture to the atmosphere depending on the RH of the environment it is in. Will this b a problem for you.

Regards
Pat
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[recordman]

Ooh yeah, expansion/contraction would make the lacquer grooved surface crack up. I didn't know nylon did that.

I would like to find a plastic which can be sent through the same electroplating process as traditional metal-based lacquers, for making nickel stampers to mass-press vinyl records. If nylon absorbs moisture, hopefully PVC (or your other 2 suggestions, polyester or acetal) will work.

I will at some point also be acquiring equipment to make metal based ones, as well as perhaps offering a recoating for those who turn in their cores from used master discs, but would like alternatives for cheaper product lines.

During WWII, with the metal shortage, they used glass-based master discs, but I'd rather avoid that. They were sanded to make it adhere "as good as possible". It would flake off over time, but stuck long enough to serve its purpose of immediate playback, or metal-plating for mass-pressing shellac copies.

The plating process involves spraying a liquid silver compound onto the grooved lacquer surface, then attaching a terminal at the center hole to electrify that surface, & submerging the disc in an electrolytic charged bath to build up the thin silver initial coating with nickel. Guess I need to research those chemicals to ensure they won't react badly with the plastics (although they apparently don't harm nitrocellulose lacquer)... sometimes I really wish I was a chemist

- recordman

 

[patprimmer]

Many plastics can theoretically be electroplated by either treating with a process called electro less nickel or treating in a solution of cupramonium hydroxide. I have seen both nylon and acetal plated in the lab by the cupramonium hdroxide method. I have seen ABS and PC/ABS plated commercially.

Both these processes deposit a thin layer of metal. Once the surface is coated with metal, it can then be plated by normal electrolytic means. These chemicals can attack the surface of the plastics and cause solvent stress cracking. If they do not attack the surface at all, the plating does not stick.

In the real world, special grades of ABS and to some extent PC/ABS alloys are the only plastics successfully plated to prduce a durable serviceable product.

Regards
Pat
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[Demon3]

Pat made a good point. When you plate ABS, first you etch out the rubber particles to leave holes that allow you to get bonding through mechanical interlocking.

Another, new way we recently developed by BASF whereby they use a special additive in ABS to improve the bonding to metal. I don't know the grade name but you can probably contact them and find out.

Chris DeArmitt

"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill

 

[Compositepro]

The silver plating process that recordman refered to does the same as electoless nickel. It allows for electroplating.
The electroplating is very thick and you do not want it to stick to the laquer. The electroplate becomes the mold that has been made from the laquer master. See what you can learn from watching "How It's Made".

 

[recordman]

Yes, what Compositepro said... But thanks Patprimmer and Demon3, I'm also interested in all kinds of electroplating, and the info you mentioned may come in useful. I'm contemplating a career change from software engineering to mech e., with a special interest in designing, or at least planning out production lines using existing, industrial equipment of all kinds.

 

[dwightdixon]

There are a lot of electroform houses in business in the USA with excess capacity. Where in the US are you located? It might make more sense to farm out the mold making to someone who does it for a living than trying to buy all the equipment and learn the hard way all the tricks. Simsonite in Chicago has a very nice line. I build an electroform mold making facility for Baxter but decided after we spent the money, we were better off going on the outside.

 

[vinylguru]

Hey Recordman
I am interested to know what type of lacquer compound are you going to use as it is of immense interest to me
In so far as the methods you are considering concerned I am not sure that drying the material vertically will be of any use It may be a good thing for you to have a look at a couple of clips on Utube they are: How vinyl records are made, part 1 shows quite clearly how lacquer masters are made at Transco a well respected long standing maker of acetates
Some comments may also be called for as well The etching process applied to ABS compounds is to be avoided in so far as an acetate to be used as a master for making a mother or a convert from it is concerned
I can assure you that your PVC blanks will be useless as a backing for lacquer masters as used in cutting records, they have a radious shape from the thick part to the outside Further the have a thiccker section on the perimeter so as to guide the play back stylus into the starting spiral The varying thicknes of the vinyl record is there so as to keep the vinyl records flat, stop them from "dishing" whereby an acetate lacquer master has to be perfectely flat
Cutting a lacquer on a lathe is done with a linear moving cutting stylus rather than the eliptical movement that a turntable arm moves
I cannot see how a 50-60 micron wide cut will be ever put on a blank that has come out of a record die unless of course you are cutting a very deep/wide track which will be most likely be played back with a 78 rpm shelack "nail"
Using any industry standard cutting lathe it will be an absolute NO NO
In so far as the "silvering" method is concerned the idea is to have a layer of silver in to the lacquer in other words a single atomic layer Enough to make the lacquer conduct current The recomended thicknes is between 61-123 mm x 10-6 That is some millionths of an inch thick No silver plating is ever done A smoothing layer of nickel is first applied in a very low current/voltage Nickel Sulfamate bath for about 10-20 Minutes the plates are than transfered to the standard plating baths where the elctroforming of the master is completed over three distinct current/voltage steps It may than be used as a convert to press records direct from it as it is a negative or to make a Mother which than is a positive and than to make sons as they are than negative to form into stampers
The silver is allways stripped off from the convert or any filming used in the mother son steps leaving only the nickel In days gone past a very light chromium coating was applied to the face so as to provide the stamper with a tougher surface This was a practice in some plants not universally applied as it distorts the sound track
By the way once you have plated the lacquer keeping in mind that for a 7" you use a 10" master and for a 12" you use a 14" master if you are to use the first electroform as a convert you than cut it to the size which means the lacquer plates are unusable Also quite often the back of the lacquer strips off even when you are cutting the electroform at the absolute minimum required so as to seperated it from the acetate master The Aluminium backing used in them is anathema to the electroforming baths Impurity tolerance is not something that electroforming is known for, ie 5 parts per million of copper will give you a stamper that will last a whole two pressings before it splits that is if you are lucky I can go on for a few pages but!!Any way I am off the subject so i will leave it at that If you do have a formula for the lacquer I would like to exchange some ideas with you on the subject This may be a good thing for all concerned if it comes off
Cheers All

 

[recordman]

Hi Vinylguru,

My formula was obtained from a chemical analysis of many brands of 1940s-50s lacquer recording blanks commissioned by Library of Congress I believe (?) to study chemical breakdown of rare field recordings, and how to preserve them. It found the predominant ingredients were nitrocellulose lacquer and castor oil. It didn't give the proportions; that would require experimentation.

 

[vinylguru]

Hey Recordman
Here is a link that may be of some help to you since some one picked this post

http://lathetrolls.phpbbweb.com/viewtopic.php?t=783&mforum=lathetrolls

There is one recipe posted there so take a look and keep an eye out for more May be you sould join in the forum as well
Cheers