[Harp-L] Can you use an ultrasonic cleaner on a sealed pearwood (Hohner) comb?

OWEN EVANS owenpevans@xxxxx
Fri May 4 13:20:07 EDT 2018

That’s interesting Joe as I have seen 35% w/v at the gardening supply stores. 
Unfortunately, my attachment didn’t make it on the e-mail I sent so here is a precis of the information for this who are interested: 

https://www.cdc.gov/infectioncontrol/guidelines/disinfection/index.html <https://www.cdc.gov/infectioncontrol/guidelines/disinfection/index.html>

Hydrogen Peroxide

Overview. The literature contains several accounts of the properties, germicidal effectiveness, and potential uses for stabilized hydrogen peroxide in the health-care setting. Published reports ascribe good germicidal activity to hydrogen peroxide and attest to its bactericidal, virucidal, sporicidal, and fungicidal properties 653-655. (Tables 4 and 5) The FDA website lists cleared liquid chemical sterilants and high-level disinfectants containing hydrogen peroxide and their cleared contact conditions.

Mode of Action.Hydrogen peroxide works by producing destructive hydroxyl free radicals that can attack membrane lipids, DNA, and other essential cell components. Catalase, produced by aerobic organisms and facultative anaerobes that possess cytochrome systems, can protect cells from metabolically produced hydrogen peroxide by degrading hydrogen peroxide to water and oxygen. This defense is overwhelmed by the concentrations used for disinfection 653, 654.

Microbicidal Activity. Hydrogen peroxide is active against a wide range of microorganisms, including bacteria, yeasts, fungi, viruses, and spores 78, 654. A 0.5% accelerated hydrogen peroxide demonstrated bactericidal and virucidal activity in 1 minute and mycobactericidal and fungicidal activity in 5 minutes 656. Bactericidal effectiveness and stability of hydrogen peroxide in urine has been demonstrated against a variety of health-care–associated pathogens; organisms with high cellular catalase activity (e.g., S. aureus, S. marcescens, and Proteus mirabilis) required 30–60 minutes of exposure to 0.6% hydrogen peroxide for a 108 reduction in cell counts, whereas organisms with lower catalase activity (e.g., E. coli, Streptococcus species, and Pseudomonas species) required only 15 minutes' exposure 657. In an investigation of 3%, 10%, and 15% hydrogen peroxide for reducing spacecraft bacterial populations, a complete kill of 106 spores (i.e., Bacillus species) occurred with a 10% concentration and a 60-minute exposure time. A 3% concentration for 150 minutes killed 106 spores in six of seven exposure trials 658. A 10% hydrogen peroxide solution resulted in a 103 decrease in B. atrophaeus spores, and a >105 decrease when tested against 13 other pathogens in 30 minutes at 20ºC 659, 660. A 3.0% hydrogen peroxide solution was ineffective against VRE after 3 and 10 minutes exposure times 661 and caused only a 2-log10 reduction in the number of Acanthamoeba cysts in approximately 2 hours 662. A 7% stabilized hydrogen peroxide proved to be sporicidal (6 hours of exposure), mycobactericidal (20 minutes), fungicidal (5 minutes) at full strength, virucidal (5 minutes) and bactericidal (3 minutes) at a 1:16 dilution when a quantitative carrier test was used 655. The 7% solution of hydrogen peroxide, tested after 14 days of stress (in the form of germ-loaded carriers and respiratory therapy equipment), was sporicidal (>7 log10 reduction in 6 hours), mycobactericidal (>6.5 log10 reduction in 25 minutes), fungicidal (>5 log10 reduction in 20 minutes), bactericidal (>6 log10 reduction in 5 minutes) and virucidal (5 log10 reduction in 5 minutes) 663. Synergistic sporicidal effects were observed when spores were exposed to a combination of hydrogen peroxide (5.9%–23.6%) and peracetic acid 664. Other studies demonstrated the antiviral activity of hydrogen peroxide against rhinovirus 665. The time required for inactivating three serotypes of rhinovirus using a 3% hydrogen peroxide solution was 6–8 minutes; this time increased with decreasing concentrations (18-20 minutes at 1.5%, 50–60 minutes at 0.75%).

Concentrations of hydrogen peroxide from 6% to 25% show promise as chemical sterilants. The product marketed as a sterilant is a premixed, ready-to-use chemical that contains 7.5% hydrogen peroxide and 0.85% phosphoric acid (to maintain a low pH) 69. The mycobactericidal activity of 7.5% hydrogen peroxide has been corroborated in a study showing the inactivation of >105 multidrug-resistant M. tuberculosis after a 10-minute exposure 666. Thirty minutes were required for >99.9% inactivation of poliovirus and HAV 667. Three percent and 6% hydrogen peroxide were unable to inactivate HAV in 1 minute in a carrier test 58. When the effectiveness of 7.5% hydrogen peroxide at 10 minutes was compared with 2% alkaline glutaraldehyde at 20 minutes in manual disinfection of endoscopes, no significant difference in germicidal activity was observed 668. ). No complaints were received from the nursing or medical staff regarding odor or toxicity. In one study, 6% hydrogen peroxide (unused product was 7.5%) was more effective in the high-level disinfection of flexible endoscopes than was the 2% glutaraldehyde solution 456. A new, rapid-acting 13.4% hydrogen peroxide formulation (that is not yet FDA-cleared) has demonstrated sporicidal, mycobactericidal, fungicidal, and virucidal efficacy. Manufacturer data demonstrate that this solution sterilizes in 30 minutes and provides high-level disinfection in 5 minutes 669. This product has not been used long enough to evaluate material compatibility to endoscopes and other semicritical devices, and further assessment by instrument manufacturers is needed.

Under normal conditions, hydrogen peroxide is extremely stable when properly stored (e.g., in dark containers). The decomposition or loss of potency in small containers is less than 2% per year at ambient temperatures 670.


Uses. Commercially available 3% hydrogen peroxide is a stable and effective disinfectant when used on inanimate surfaces. It has been used in concentrations from 3% to 6% for disinfecting soft contact lenses (e.g., 3% for 2–3 hrs) 653, 671, 672, tonometer biprisms 513, ventilators 673, fabrics 397, and endoscopes 456. Hydrogen peroxide was effective in spot-disinfecting fabrics in patients' rooms 397. Corneal damage from a hydrogen peroxide-soaked tonometer tip that was not properly rinsed has been reported 674. Hydrogen peroxide also has been instilled into urinary drainage bags in an attempt to eliminate the bag as a source of bladder bacteriuria and environmental contamination 675. Although the instillation of hydrogen peroxide into the bag reduced microbial contamination of the bag, this procedure did not reduce the incidence of catheter-associated bacteriuria 675.

A chemical irritation resembling pseudomembranous colitis caused by either 3% hydrogen peroxide or a 2% glutaraldehyde has been reported 621. An epidemic of pseudomembrane-like enteritis and colitis in seven patients in a gastrointestinal endoscopy unit also has been associated with inadequate rinsing of 3% hydrogen peroxide from the endoscope 676.

As with other chemical sterilants, dilution of the hydrogen peroxide must be monitored by regularly testing the minimum effective concentration (i.e., 7.5%–6.0%). Compatibility testing by Olympus America of the 7.5% hydrogen peroxide found both cosmetic changes (e.g., discoloration of black anodized metal finishes) 69 and functional changes with the tested endoscopes (Olympus, written communication, October 15, 1999).

> On May 4, 2018, at 11:25 AM, Joseph Leone <3N037 at xxxxx> wrote:
> Higher concentrations of hydrogen peroxide are available at beauty supply sources. As high as 9. I recommend 6%.
> ‘broken shoe joe’
>> On Apr 30, 2018, at 4:12 PM, OWEN EVANS <owenpevans at xxxxx> wrote:
>> You are partially correct Mr. Feldman. Please have a read about this as there are more bugs in spit than just flu virus.
>> https://www.nhs.uk/chq/Pages/how-long-do-bacteria-and-viruses-live-outside-the-body.aspx?CategoryID=200&SubCategoryID=2001 <https://www.nhs.uk/chq/Pages/how-long-do-bacteria-and-viruses-live-outside-the-body.aspx?CategoryID=200&SubCategoryID=2001>
>> I can tell Mr. Marsolais that I have placed lots of sealed combs in an ultrasonic cleaner using 3% w/v Hydrogen Peroxide for 15-20 minutes. It works well. I currently use Crossovers & they are sealed bamboo & clean up fine. I’d be concerned about old pearwood combs as they were not sealed & may absorb liquid thus warping!
>> If you can get higher concentration H2O2 it will work faster. Attached is a paper on use of H2O2 for this purpose.
>> Cheers,
>> Owen

Owen P. Evans
25 Hexham Road
Ottawa, Ontario. K2H5L3

owenpevans at xxxxx

The harmonica is the most voice-like instrument. 
You can make it wail,  feel happy or cry. 
It’s like singing the blues without words!

Charlie Musselwhite

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