Re: [Harp-L] Valves/windsavers

[Vern <jevern@xxxxxxx>]

On Jan 12, 2010, at 4:39 AM, Aongus Mac Cana wrote:

> I have eyed up the sealing film on yogurt cartons as a likely material for
> making replacement valves, but was discouraged from this idea in a workshop
> session where Rick Epping informed us that a windsaver is not just a simple
> flap of plastic, but that it has two components: the spring and the sealing
> membrane.

Almost any thin plastic film will perform the primary function of the valve.  However most films are hard, making a noise when they close, and smooth, allowing a film of condensate to cause the valve to adhere to the plate.  

The traditional factory valve design uses two layers,  The top layer is springy to keep the valve close to the plate and the lower layer is softer and textured to comply to the plate surface, to avoid noise when the valve closes and to reduce the area in contact with the plate to minimize the adherence of the condensation.  However, the factory valves do have problems.  They curl up and rattle when the upper and lower layers get stuck together and they also stick and pop when wet.  In an attempt to overcome these problems, some new designs use more extreme texturing of the lower layer and longitudinal crimps in the upper layer.

Experimental single-layer materials have met with some success:
- Teflon-coated fiberglass (Dupont Bakeware Liner) was used in The Renaissance harmonica. It is not immune to sticking and popping when wet.
- Micropore medical tape stuck to mylar (polyester) film has been used by many players.
- Compressed and waterproofed Ultrasuede (artificial leather) is my current enthusiasm.

> In vintgage accordeons there was apparently an actual metal 'hairpin' spring
> which closed a leather flap.
> Nowadays I understand that harmonica valve material may in fact comprise a
> lamination with the "spring" material on top and the sealing element
> underneath. Consequently it might be possible to inadvertently mount a valve
> upside down and get less than terrific results.

Your statement is certainly true. However, anyone who would inadvertently mount a valve upside down shouldn't have the covers off his harp.

Vern