Valve Shapes & Materials

A space for players interested in my specialist harmonicas, alternate tunings, instructional material, recordings etc to ask questions and share information, experiences, videos etc.
Post Reply
User avatar
Brendan
Posts: 663
Joined: Fri Mar 24, 2017 2:28 pm
Contact:

Valve Shapes & Materials

Post by Brendan » Sun Dec 06, 2020 2:54 am

Over the past few days I've spent a lot of time experimenting with valve materials and shapes. Mostly in relation to my multi-valve Gasket-Valves for chromatic harps, but the principles apply to single valves also.

Most harmonica and accordion valves are made of two parts: the flexible valve itself resting on the reedplate, and a stiffer spring above it, which returns the valve to a flat position after being activated. Generally the valve has some under layer which is slightly textured and preferably soft, to reduce capillary attraction and noise.

Diatonic harps only require 'sitting valves': that is, ones which sit down naturally with gravity, on the upper surfaces of the reedplates. They're either on the inside of the draw reedplate, or the outside of the blow reedplate. In these positions, soft flexible valves work fine without a spring, because they always return to the flat position under their own weight.

In chromatics, half the windsavers are ’hanging valves’, mounted on the underside of the two reedplates, fighting gravity to return to the flat resting position. Valve materials which are fine in diatonics won't necessarily work well in chromatics.

For example, PT Gazell's thick Ultrasuede valves work well in diatonics, but are too floppy and heavy to function as hanging valves in a chromatic harmonica. For chromatics you either need two-piece valves with a spring, or a light material with enough inherent springiness to combat gravity and return even the longest lower valves to rest on the underside of the reedplates, over decades of hard playing!

Whilst two-piece valves work well enough, I'm always searching for the perfect one-piece valve solution. It's not easy to find!

Some contenders are laminated valves: two materials with useful qualities, springiness and softness, bonded together. Wally Peterson came up with a good combination many years ago: thin Mylar sheet stuck to Micropore medical tape. Mylar (a trade name for Polyester sheet) is thin, springy, and wants to return to its flat original profile. Micropore is soft, flexible, and conveniently adhesive, so you just stick it on the Mylar and cut valves out of it. He's been selling single valves in this laminate material for many years.

For my Gasket-Valves I also prefer to choose a one-piece option. Whilst they can be designed to be made with separate valve and spring layers, keeping cutting simple as well as maintaining the smallest overall thickness are both important criteria. Laminates can work, but they add complexity, time and hassle to the manufacturing prices. So I prefer to stick with one-piece valves made of a single material.

Finding the ultimate single valve material is a fascinating, never ending quest! It has to combine several desirable qualities together - mainly the right amount of springiness, plus a textured surface to avoid capillary attraction. Few materials fit the bill.

One interesting option was found by the late great Doug Tate, co-designer with Bobbie Giordano of the highly innovative Renaissance chromatic harmonica. He cut his valves out of bakeware liners! They're composed of non-stick Teflon covering a thin fibreglass weave, so you get both of the main desirable qualities of good valves in one.

(To be continued...)

User avatar
Brendan
Posts: 663
Joined: Fri Mar 24, 2017 2:28 pm
Contact:

Re: Valve Shapes & Materials

Post by Brendan » Sun Dec 06, 2020 9:34 am

I tried it recently for my Gasket-Valves, but the stuff I have is rather shop-worn and a bit crinkled, so not all valves laid flat. I've ordered a new batch, will report back soon.

The best single-material valve solution for both sitting and hanging valves I've found so far is textured polypropylene. This is what I be been using for my Gasket-Valves, for both diatonics and (recently) valveless chromatics.

The stuff I choose has an inherent curl, which I use to my advantage by cutting the valves so they have a slight inward curve as they rest on the reedplate. The curve provides the spring quality, ensuring they always return to the home position, sitting or hanging. Your breath flattens the slight curve instantly when the valve is activated, to seal it shut. The texture and inherent slipperiness of polypropylene combats capillary attraction - so that's several boxes ticked!

However, polypropylene is a hard plastic, so it's a bit noisy in operation. I've found the noise factor of valves is somewhat psychological: like the clacking of an accordion keyboard or the squeaking of an acoustic guitar's strings, you can subconsciously blank out the sound of valve slap in harmonicas when playing or listening. All valves, even the softest ones, make SOME noise, if you care to listen for it. The trouble is, once you do, it's hard to switch off again! So naturally it's preferable to minimise the noise as much as possible.

To that end, yesterday I experimented with radically reshaping my polypropylene Gasket-Valves to virtually eliminate the contact of valve on reedplate, which is where that 'slappy' sound originates.

Check these ones out... You can see the inherent inward curve of the material. The tips are narrowed to the width of the reed slot, and actually curve into the slot at rest. I'm quite liking this. It reduces the contact noise from this hard material, but retains its convenience and other good qualities.

Not a perfect valve solution (is there such a thing?) but an interesting direction to pursue.
IMG_20201205_133105_compress52.jpg
IMG_20201205_133105_compress52.jpg (279.52 KiB) Viewed 1640 times
IMG_20201205_133235_compress90.jpg
IMG_20201205_133235_compress90.jpg (217.34 KiB) Viewed 1640 times

User avatar
Brendan
Posts: 663
Joined: Fri Mar 24, 2017 2:28 pm
Contact:

Re: Valve Shapes & Materials

Post by Brendan » Sun Dec 06, 2020 9:56 am

Of course, as ideas come along, I'm constantly testing other valve options too... Here's a more conventional shape using Walley Peterson's Mylar/Micropore laminate:
IMG_20201205_121438_compress99.jpg
IMG_20201205_121438_compress99.jpg (503.32 KiB) Viewed 1638 times
I've used it before but found it wasn't entirely predictable over time, sometimes leading to valves curling in the wrong direction. This could come down to how I stuck the Micropore tape on at the beginning, or how it was cut... Not sure. But it's enough to put me off selling the things until I understand what's going on.

I'm also exploring making Gasket-Valves using the traditional two-piece design: soft flexible valves with a tougher spring material above to keep them flat, sitting or hanging. There are a few challenges here, in cutting the soft material, and to keep the thickness of the combination down to a minimum, but it's possible.

It's not my preferred option; I still believe the perfect One-piece Valve Material is out there, somewhere! But it could be a necessary solution until the Holy Grail is found.

vesuviation
Posts: 8
Joined: Tue Nov 17, 2020 1:29 pm

Re: Valve Shapes & Materials

Post by vesuviation » Mon Dec 07, 2020 11:26 pm

Thanks a lot for your work, will apply as beta tester 😀

User avatar
Brendan
Posts: 663
Joined: Fri Mar 24, 2017 2:28 pm
Contact:

Re: Valve Shapes & Materials

Post by Brendan » Thu Dec 17, 2020 8:50 am

I'm still at it! Have ordered all kinds of materials to try on their own, or laminated together. Been talking to my engineer friend Zombor Kovacs about valves too - he's done extensive study of this vexing topic for his brilliant ExtraBend harp.

He finally concluded, like all the manufacturers, that you need two piece valves: soft flexible under layer and separate upper spring. He likens laminating them together to "Driving with the brakes on'': the qualities of each material undermines the effectiveness of the good qualities of the other.

I'm reluctant to throw in the towel on finding the perfect single valve material just yet. The best stuff in general is Mylar/Polyester, as it's very rugged and always returns to flat. But it's hard, noisy and sticks with capillary attraction in the standard smooth sheet form. I'm now looking into textured polyester sheet. The good news is that there's lots out there to try 👍

Another option is some kind of woven polyester that combines flex, spring and softness in one material. I have a few promising samples ordered which I'm keen to try soon.

A further option is spray coating the underside of polyester sheet with a thin soft layer, which is something the harmonica companies have done. I'm pretty sure Hohner's old valves were like that, and Hering's too. Will test that option shortly as well.

In the meantime my current polypropylene material with its slight inbuilt curve ticks most of the boxes - except for noise. Will try coating that too.

These tiny things are a tough nut to crack! It's certainly keeping me engaged and amused 🙂👍

User avatar
Brendan
Posts: 663
Joined: Fri Mar 24, 2017 2:28 pm
Contact:

Re: Valve Shapes & Materials

Post by Brendan » Thu Dec 17, 2020 8:52 am

I'm still at it! Have ordered all kinds of materials to try on their own, or laminated together. Been talking to my engineer friend Zombor Kovacs about valves too - he's done extensive study of this vexing topic for his brilliant ExtraBend harp.

He finally concluded, like all the manufacturers, that you need two piece valves: soft flexible under layer and separate upper spring. He likens laminating them together to "Driving with the brakes on'': the qualities of each material undermines the effectiveness of the good qualities of the other.

I'm reluctant to throw in the towel on finding the perfect single valve material just yet. The best stuff in general is Mylar/Polyester, as it's very rugged and always returns to flat. But it's hard, noisy and sticks with capillary attraction in the standard smooth sheet form. I'm now looking into textured polyester sheet. The good news is that there's lots out there to try 👍

Another option is some kind of woven polyester that combines flex, spring and softness in one material. I have a few promising samples ordered which I'm keen to try soon.

A further option is spray coating the underside of polyester sheet with a thin soft layer, which is something the harmonica companies have done. I'm pretty sure Hohner's old valves were like that, and Hering's too. Will test that option shortly as well.

In the meantime my current polypropylene material with its slight inbuilt curve ticks most of the boxes - except for noise. Will try coating that too.

These tiny things are a tough nut to crack! It's certainly keeping me engaged and amused 🙂👍

Post Reply