After reading the “sulphonic soap” recommendation from Ortofon posted in another thread, I decided to experiment with Dawn dishwashing detergent in my Humminguru.
I found an old moldy Chubby Checker record without an inner sleeve in our house. Normally, a record in this condition I’d prefer to clean first on the Record Doctor RCM before putting into the Guru.
I used 0.1 ml of Dawn in the tank with 375ml of distilled water and ran it for two full wash cycles and one final 5 minute drying cycle. The record was fully wet by the mixture and had minimal foaming. A mildly objectionable part here was the intense perfume scent that came from aerosolizing the Dawn - I used standard Dawn versus Free and Clear.
Once out, the record no longer had visible surface mold, but did have a couple of chunks of material that the Guru did not remove. It also did not come out fully glossy but a bit dull, which I could not attribute to the cleaning fluid or just the record condition.
I used a wet, wooden-handled swab to remove the stuck material and to circle around the label and deadwax where it’s hardest for the Guru to clean. I found that the swab was darkened by the deadwax, indicating the record was not fully clean.
The record went back into the Guru with just distilled water alone, after rinsing the tank and filter. I ran this cycle for 5 mins clean, 5 mins dry. The record still had a couple of drops on each side, which was not the case in the first run.
I reran a swab on the deadwax and found minimal darkening. However, when I ran the swab along the lead-in groove, it was darkened by residual dirt.
Another swab ran against a gap between songs in the middle of the record produced minimal, but nonzero, darkening of a swab. The record looked superficially “clean” for a record of this age and condition, but not glossy.
Not wanting to put a dirty record back on the shelf, I resorted to my old, pre-RCM method of cleaning - a diluted cleaning spray with paper towel scrubbing. It took a couple of paper towels per side before a towel would show without dirt. I popped the record back into the Guru for a quick rinse/dry in distilled water before putting it into a new sleeve for storage. It was a bit more glossy at this point; I’d play the record in this condition but did not choose to do so.
So, what did I learn?
- I should continue a physical contact, two-step washing of really dirty records - the Guru probably can’t deep clean them alone without three or more full cycles.
- Dawn is probably a good wetting agent and detergent, but it won’t work miracles in the Guru with cruddy records. If I use Dawn again, I’d opt for the Free and Clear variety. I did not establish that it really was any better (or worse) than another surfactant. I’d consider using it when doing a contact clean of a record.
- Really dirty records that have been ultrasonic cleaned and look clean to the eye may still have residual dirt. I need to test those records with a wet swab after cleaning.