Acetal copolymer, pvc and delrin.??? whats the difference

[sponge]

Hi Guys and gals,

considering another whistle, something synthetic as opposed to alloy,
just wondered if any of the guys making whistle on the forum or girls
can tell me the differences in these three materials, I'm not interested in the sound attributes, just really what makes them different and what would be classed as the most durable for all conditions, I was just looking at all the options on whistle made of these materials, i.e Paul Busman and Chris Abell, both do a delrin model, where as Paul Hayward ( silkstone whistles ) does the lovely looking ace models in acetal copolymer, and he also works with PVC. I'm not sure what the dixons are made of, it would be interesting to know which material was the most durable, in all climates, weather conditions, etc.

[Jerry Freeman]

Delrin is Dupont's brand of acetyl copolymer.

PVC is a different material (polyvinyl chloride). Acetyl is probably tougher than PVC, but PVC is a very durable material in its own right.

Acetyl/Delrin is denser than PVC. Most people consider the density of a material one of the main things that determines its suitability for many musical instruments (denser usually is better). That's one of the reasons why the very densest woods (blackwood, cocobolo, boxwood, etc.) are the most fovored woods for whistles, flutes, etc.

Best wishes,
Jerry Freeman

[billw]

Delrin is DuPont's proprietary name for acetal. (Oops, Jerry already said that! ) It's dense and low-friction. The first place I ever saw it was as a speedometer gear in a tranny on a 1966 Chevrolet van. It was invented around 1956. The fact that it can be used for precision gears in motor vehicles speaks well of its dimensional stability and strength at just about any temperature.

As Jerry says, PVC ia also quite durable, and it is very much used in musical instruments, and has good properties in its own right. I use the chlorinated (CPVC) version for my soprano Brassy Polly, as since it holds up better to pressure under high temps, the wall thickness can be a bit less for the same ID than plain PVC.

But I still prefer chrome molybdenum steel, with its hard cryptocrystalline structure, as it is far more resonant than wood, brass, nickel, or any of the plastics. But the teensy steel slivers from milling can be extremely annoying to have to remove from your fingers! O.o

All that said, I probably play my Busman ebony more than any other. I don't even have a VS of my own, which I intend to remedy soon as I get back to Alpharetta! There's a Ned Kelly model alto A in that 2 dozen to be completed!
Bill Whedon

[Dralore]

There are different types of Acetyl as well. You have Copolymers and Homopolymers. And with in thoses, there are sub-types. Thats not including color but just compositions. Acetyls arguably do make better instruments. The price for the material is far greater than PVC or CPVC, And it is harder to machine to an extent. Acetyls will sound closer to wood than the PVC's because it is closer to the density of wood. Your higher end synthetic instruments are made from Acetyl Polymers. Hope this has helped.

[peeplj]

I have flutes made of PVC (M&E) and of Delrin (Seery).

I think the cut of the embouchure, the bore profile, and the tone holes have a far greater affect on the sound of the flute than any difference between plastics.

After all, blackwood is denser than boxwood...does blackwood make a better flute, or just a different flute?

--James

[brewerpaul]

Some really dandy instruments can be made from PVC, such as the late Glenn Schultz's Water Weasels. Others like our own Dan Bingamon use PVC too, although I've only tried his brass whistles. Since you can buy this stuff cheaply in ready made tube form at any hardware store, PVC whistles can be made with less labor and hence lower price.
Acetal comes in solid rods which have to be machined just like wood. Therefore, the labor involved in making an Acetal is almost exactly like that in making a wooden whistle and the resulting price is similar. There is also acetal tubing, but it's not the right dimensions and needs almost as much machining to get it there. One nice thing is that acetal comes in colors (see my avatar). This has not proved to be very popular for me though.
Another disadvantage is that acetal is a b*tch to glue. I called Dupont for their advice and the response I got was (I am not making this up) "Good luck!".

[crookedtune]

I have flutes made of PVC (M&E) and of Delrin (Seery).

I think the cut of the embouchure, the bore profile, and the tone holes have a far greater affect on the sound of the flute than any difference between plastics.

After all, blackwood is denser than boxwood...does blackwood make a better flute, or just a different flute?

--James

I agree. In fact, I recently bought a used delrin Pratten-style flute made by Jon Cornia (a Cochran). When asked, Jon told me he felt the sound of delrin and blackwood was pretty much indistinguishable in his flutes, though he noted that boxwood has a more buttery sound.

Some still frown on polymers, but I believe the cut of the instrument and the player's ability have a far greater impact on the sound than the material, ESPECIALLY in flutes. And they're so easy to care for!

[sponge]

Thanks all,

great bit of information, Thats cleared that up for me, I was unaware that Dupont's material was the original delrin, I guess that all the manufacturers of acetal copolymers use a simmilar formulation, and different brand names.

So having sorted that out, has anyone played the Silkstone ace high D whistle,????? an all delrin construction with very nice steel rings, and a 7th
hole option for the C nat. pricey but a fair bit off work going on its creation so it all balances out.

sponge

[brianormond]

-Delrin and the like are incredibly tough materials. I rebuilt a corroded farm conveyor using UHMW (ultra high molecular weight) acetal plastic paneling to replace steel side-gussets which prevent soil spill. Panels cut to size easily enough on a band saw but countersinking them on-site to allow flathead screws to lie flush was extremely difficult. Steel is easier
to work.

[syn whistles]

Here's a couple more points about plastics and materials.
Acetal (or Delrin) is a "Food Grade" plastic. I don't think PVC is rated to that grade. You can draw your own conclusions about what to put in your mouth!
I was at a seminar recently where it was claimed that it is the porosity of the material, rather than its' density, that makes the difference in sound. Very often the two are linked and so the density gets the credit when it is actually due to the porosity.

[peeplj]

Here's a couple more points about plastics and materials.
Acetal (or Delrin) is a "Food Grade" plastic. I don't think PVC is rated to that grade. You can draw your own conclusions about what to put in your mouth!
I was at a seminar recently where it was claimed that it is the porosity of the material, rather than its' density, that makes the difference in sound. Very often the two are linked and so the density gets the credit when it is actually due to the porosity.

I can't speak to every maker out there that uses PVC, but I know that Michael Cronnolly orders PVC rod stock (not tubing) from which he machines his instruments. This PVC is certified non-toxic and is not the same PVC material commonly found in hardware stores. I believe he gets it from Germany, although I may be wrong on this point.

I believe the late Glen Shulz used PVC hot-water pipes to make his whistles, which of course would also be non-toxic.

--James

[brewerpaul]

Here's a couple more points about plastics and materials.
Acetal (or Delrin) is a "Food Grade" plastic. I don't think PVC is rated to that grade. You can draw your own conclusions about what to put in your mouth!

>On the other hand, PVC is rated for plumbing drinking water pipe, hot and cold.

I was at a seminar recently where it was claimed that it is the porosity of the material, rather than its' density, that makes the difference in sound. Very often the two are linked and so the density gets the credit when it is actually due to the porosity.

> I'll buy that. That's why Maple whistles sound really cruddy and weak until you oil them or seal the bore with something eg polyurethane. Compared to a lot of the exotic woods, Maple is quite porous

[Loren]

Yeah, but it's also a lot less dense,



Loren

[C age ing]

Yeah, but it's also a lot less dense,



Loren

I'm incredibly dense, I know, the teacher told me. Will that make me a good sounding whistle player?
Bill

[Loren]

Sorry, if it hasn't worked for me, I don't think it's going to work that way for anyone.

Loren