Posts tagged sand
I must say if there’s one thing i know little about, it’s the COMPARISON of cast iron plates in pianos with regards to tone. We don’t really have the luxury of comparing identical models of pianos with different cast plates in them. I am referring to the difference between traditional sand cast plates vs. V-Pro casting. I can spot a traditional sand cast plate a mile away but does it affect tone? Hmmm i’m not so sure… but here’s what i DO know (which might be dangerous – as they say “a little knowledge is dangerous”)…
Traditional sand casting: Make a model. Press it into sand… remember making a mold of your hand in plaster when you were a kid? Same thing except that the master model is a piano frame. Once the ‘relief’ is in the sand, they pour molten iron into the mold.
V-Pro casting: Make a model. Cover with a plastic sheet. Add sand on top of that. Sandwich with another layer of plastic. Using a vacuum (V, by the way stands for Vacuum… Pro is for process = V-Pro)…. suck the atmosphere out of the sand bag sandwich and it very accurately mirrors the model. That then becomes the new relief mold. Make sense? Have you ever seen those ads on TV for leftover food where they suck the air out of the bag and it tightly forms around the contents? Well that’s what’s happening here.
So what does it matter? If it’s traditional sand cast or v-pro? Well the sand cast looks rough while the v-pro looks absolutely finessed. There’s barely any finishing required on v-pro while the sand cast needs a fair bit of attention to call it complete. I read today that the v-pro plates create bad harmonics. Though i’m not ruling it out, I’m not buying that either. I don’t doubt that the cast may be vibrating, but by comparison to a wooden soundboard and felt hammers, i truly believe that the bulk of any overtones are going to be coming from the interaction of those parts rather than the cast. So why the big deal? If iron is iron and one comes out looking better than the other, why do some people talk about v-pro like it’s in question? I’m not entirely sure but i have some hunches. If the sole purpose of the frame is to be the backbone of the piano – the rigid stabilizer – then mass is always better. Quite often to compensate for traditional gravity based casting, the “more is better” motto is applied. If it means that they make a bigger, chunkier plate JUST to make sure that all of the cracks and crevices get filled in when pouring, so be it. In the v-pro arena, casting is much more accurate and is also more efficient. My own thinking is that the cast iron pianos with v-pro are thinner. That’s my wager. From the pianos i’ve seen (especially older ones) where they are really robust, invariably the cast iron frames are also beefy. Back in January – visiting a few boutique piano manufacturers, one intimated that the casts were traditional sand cast… intimating they were somehow superior. Isn’t that interesting? Low-tech can still be considered superior? Well jury is out for me. I can’t actually speak from personal experience because i’ve only seen isolated cases on both sides for comparison. And really, there are WAY more variables than just the cast from which to compare. I’ve never seen two pianos from the same year, model, size etc with 2 different plates to compare. But i WILL go on record saying that there is ONE thing that i do know to be generally true: heavier pianos (ie more iron) are USUALLY better instruments. Other than that… my little knowledge… is just… dangerous.
I wish, i wish, i wish i would’ve had someone guide me through the process of refinishing when i was young. A friend of mine says “Good judgement comes from good experience. However, good experience comes from bad experience.” Hahaaaa and he also says “The difficult we can do… the impossible may take some time”. lol… so refinishing has been years (read 15) of learning what NOT to do. And in an ever changing world of finishing… (ie products are now switching from solvent base to water base) there is still a lot of trial and error involved.
Why refinish old pianos? Well i consider pianos about the same size as small elephants in a living room. So who wants to look at a crusty old elephant every day. And besides, the manufacturers of yesteryear took GREAT pride in beautifying these instruments. I remember this one time buying an old piano that they couldn’t GIVE away because it was so ugly. Below is the picture of this piano. I had NO idea that under layers of darkened ‘alligatored’ finish – where it becomes rough and bumpy – was this BEAUTIFUL wood. Presently i’m working on yet another beautifully carved instrument (top left and bottom pics).
So if you want to get into refinishing… i just want to say that you need to know some facts.
1. 99% of pianos are veneered – meaning the decorative wood on the outside is only about 1/16″ thick. Now before you start blathering on about how your piano is solid blah blah blah… i just want you to know that i’ve heard it all before. And i’ve only seen 4 pianos in my life that are solid wood. Decorative woods are generally not great structural woods. So if your piano is beautiful… it probably is not the core wood but rather laminated to another firm wood like oak. The oldest grand piano i’ve had in my shop dated 1855… and yep, it was veneered rosewood. Believe it or not, they had the technology back then. And i doubt whether many of you have older pianos than that. FYI, it was a Broadwood 8′ straight strung piano – a 30 year newer version of Beethoven’s. It’s now in a museum.
2. Piano finishes consist of layers. What you SEE consists of 3 layers – veneer base, color coat and clear coat. So our eyes see through the clear coat to the color layer on top of the wood (veneer). When you refinish a piano, what is happening is that you’re actually removing the top clear layer (which has gone bad – cracked, chipped, alligatored) and with that quite often comes off most of the color layer down to the veneer.
3. There are ONLY 2 ways to effectively remove finish: chemical and scraping. I have seen TONS of mishaps by people who think they can sand their way through the finish. In 15 years i’ve NEVER seen a competant job of ANYONE who has successfully done this. Why? Too high a grit paper (220-400) and the finish will melt with friction and clog the paper. Too low grit (50-180) and it’ll not only chew through the finish but right through the veneer as well. So how does one remove the finish? Chemical stripper (nasty stuff) is what is used mainly by furniture refinishers. The alternative is to scrape off the finish using a scraper. Scrapers will only get off about 85% of the finish and the remainder still must be done by chemical washing.
CAUTION: Please please please protect yourself if you ever venture into refinishing. Use gloves and mask to protect your skin and lungs!