Piano World Home Page Forums Our Most Popular Forums Piano Forum Wet Sand Casting versus "V-Pro" Casting for Piano Harps

What type of casting is used for the plates in Boston pianos (which are made by Kawai)? I would guess V-process. (Does Kawai even have a wet sand casting foundry?

The foundry where NY Steinway plates are cast:

https://www.npr.org/2013/11/09/243988349/in-the-heat-of-the-foundry-steinway-piano-hearts-are-made

I wonder whether the idea that sand cast plates are superior to vacuum cast plates originated with Steinway a few decades ago as they found themselves in fierce competition with the much more affordably priced Yamahas.

In the 1970's when CBS owned Steinway, quality suffered much while Yamaha quality improved. I don't think the perception of superior plates would have mattered.

sonepica, The plate has a profound influence on piano tone. How well it is configured to allow for the strings to pivot at the termination points and how well it damps Longitudinal mode issues.

The Piano Buyer article about plates omits much significant material, such as the influence the cooling rate of the iron alloy in determining the crystal form the carbon takes. The slower it cools, the more the carbon forms as a flat sheet like graphite. The faster the same alloy cools, the more the carbon in it is cubic like diamond.

The "diamond" form is very abrasive to the strings at the termination point as one tunes them.

This is why Yamaha/s, (and other makes with hard V-bars), tuned often such as in recording studios or concert halls start shedding treble strings after about ten years.

If sand cast plates are objectively superior to vacuum cast, why do Yamaha and Kawai continue to use an inferior design? Even if they were less expensive to produce, the savings would not be worth it if it resulted in a piano that was inferior to their competitors.

Yamaha spent a huge amount of money over the last twenty years doing research and development which ultimately lead to the CX and SX series. Their goal was to produce world class pianos. Why did they not switch to using sand cast, or at least make changes to the V cast method, if it is so critical?

- First, is no one going to correct the terminology? It is not a 'Harp.' It is the iron frame, or iron plate. PLEASE! A harp is a music instrument, not an iron casting.
- Next, there is no difference in tone, as other have said. The statements have been made already - in volume production, it is more efficient to use V-pro casting.
- Kawai uses V-pro in almost all models. The small volume production models - primarily the concert pianos - use wet sand casting because of low volume, and because the V-pro foundry cannot handle that large of a casting.
- I suspect Ed McMorrow has not actually visited a V-pro foundry. There is no reason for the cooling process to be different - I have seen wet sand castings get pulled out of the sand in 20 minutes after the iron is poured! In V-pro the frames spend a minimum of 1 hour in the sand, and can be left longer if the foundry is large enough. Also, I have seen PLENTY of Steinway pianos in music schools which break treble strings (in some cases needing re-stringing and capo bar shaping every year or two!) The factors for string breaking has nothing to do with the casting method, but with other factors. This argument about the carbon is based on speculation, not fact.
- Wet sand casting causes a 'skin effect' in the plate because of the flash cooling from the evaporation of water when pouring the iron. V-pro plates do not have this effect.
- You can easily tell the difference by feeling the underside of the plate through the holes. Wet sand is much more coarse and rough, V-pro is slightly rough and textured, not nearly as rough and 'sandy' feeling.

Don, is wet sand casting used in ALL of the Shigeru Kawai models? If not, which SK models DO use wet sand casting?

Also, what about the EX concert grand? Not the SK-EX, just the EX model?

The Shigeru Kawais all the way up to SK7 would use vacuum casting, as the frame would be produced using the same machinery that produces the frames for the corresponding GX piano. Presumably the concert grands including SK-EX and EX would use wet sand as they are low volume pianos.

I'm not a metallurgist, but I would expect wet sand casts would cool faster because the sand is wet, as noted above. Maybe Ed has a reference for the carbon crystal benefits of cooling of wet sand castings that are claimed to cool more slowly? Otherwise I would view it as hearsay.

Well I for one am pretty happy with my S7X. Even though it's V cast plate gives it a bright and tinny sound.

That's good to hear. Are you finding it is breaking in nicely the more you play it? How is the bass crispness coming along?

I don't have much to update on this so far. I think it needs 1-2 years. The single string C# is still much nicer than the notes around it, so there's plenty more wearing in to be done in the bass. But the whole piano will gain power and brilliance as the hammers harden. When you play octaves in the bass, it's a pretty amazing bass.

What a great feeling to know that a piano that already sounds great is going to get better and better. The only thing to keep in mind is that you need to make sure you're sharing your repertoire across many different keys!

It’s a matter of supply and demand. Wet sand caste plates is a slower process. The start up fees are considerably less for wet sand than with VPro cast but takes too long to be used on high demand plates used by high production piano models. The startup costs for VPro casting is much more expensive and it’s not profitable to use it for a few hundred pianos per year.

We need to remember the bottom line is critical to stay in business.

A lot of suppositions here. I've worked manufacturing hammers and am on agreeable terms with felt suppliers and do have some industry inside info. They and many other manufacturers are using artificial fibres in hammers.

I understand the argument why the CF uses sand cast, but it makes no sense for a market oriented company on a flagship product with a flagship procedure.

As Ed also notes, there are differences with plates. It mattered enough to Steinway that they used to make their own plates. I work with Carnegie Hall level performance artists preparing pianos and am very aware of minor differences preventing a piano from reaching the top and even if V pro can reach 99% of sand cast, the target players of the CF can tell the difference., even if you or I can't.

Ad hominen attacks usually means you can't defend your opinion or argument, so you attack the person not the argument. I know how people get attached to brands and defend their choice but all that matters is what you think of your choice. To dismiss a senior concert technician with ad hominen attacks on their expertise where you have absolutely none, belongs on Twitter, not here where we can all learn from each other.

Retired physicist here. Also, did thesis work for a materials science professor in grad school. The iron-carbon phase diagram is very complicated, but I'm not aware of any hard diamond-like phase of carbon or iron-carbon that forms in cast iron as it cools. The carbon either remains dissolved in the iron, or some of it forms into iron carbide (orthorhombic, not cubic structure) or graphite. I don't think that anyone should be concerned that there are diamond-like abrasive particles in the cast iron frame of a piano because the piano manufacturer chose one casting technique over another.

Nonsense. The difference in sound imparted by the casting method of the plate certainly is less than the variability in sound quality between two randomly chosen Steinways of the same model.

Thus, if you are talking about a 1% difference in some hypothetical quantitatve measure of quality, or the differences detected by a virtuoso that you or I could not detect, you could only make that distinction if you had two otherwise identical pianos, one with V-process plate and one with wet sand cast plate. No such comparison is even possible.