I suspect the blanket may be a factor and contributing to the issue by trapping moisture under the lid. Is there any type of haze or white film on the beams under the piano ?
I would suggest keeping the blanket off and cleaning the underside with a product that can be used on mold but always check whatever product used does not damage the finish. A small amount of murphys oil soap on a microfiber cloth may be safe. Leave the lid up to expose it to the air to dry. The use of humidifiers in the room/house may be a cause due to the mists they can create.
I have geo-thermal hvac and it is the best- very consistent, even, responsive and efficient. There is no reason to think it should be constantly running so it should be inspected by a properly trained and experienced geo-thermal technician. Regular HVAC techs have no clue- ask me how I know. I have a brand known as Water-Furnace and their techs are certified.
If the piano needs to be covered a real piano cover is recommended along with a woolen string cover. I have a full dampp-chaser and string cover on my Yamaha G2 the only reason I do not have a piano cover is that my cats would tear it up.
Mold needs moisture, darkness and a place to grow on. Is there a fire-place, pellet stove, gas log fireplace in the house causing low humidity in Winter ? Maybe a full dampp chaser is a good investment to protect year round.
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James Kelly
Owner- Fur Elise Piano Service
Pawleys Island SC
843-325-4357
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Original Message:
Sent: 04-10-2021 23:00
From: John Minor
Subject: Fine "dust" coating on underside of Steinway lid
Customer has a 1920 Steinway M that has a very fine coating of "dust" on the underside of the lid and fallboard on the decal side. I wondered if it might be mold. Customer leaves piano closed up and covered with a blanket. The dust wipes off easily, but I'm wondering if this has something to do with their HVAC being geo-thermal heat-pump that runs more constant than conventional HVAC system. Under a bright flashlight the dust has a slight sparkle to it. Any guesses on what it might be? I've seen similar dust from ultrasonic humidifiers that are known to leave a "white mist" on some surfaces.
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John Minor
The Piano Shop Inc
Champaign IL
thepianoshopcu@gmail.com
www.thepianoshopcu.com
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