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Grout gripe
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String theory When string players use vibrato, the movement of their hands looks as if they are changing the point at which the string is stopped against the fingerboard. This should change the pitch of the note. But what I hear is not a pitch change but a change in volume. Am I misunderstanding what is going on?
the string sideways to give a new note. A sideways vibrato then gives notes both above and below this pitch. In theory, you can impart more energy to the string with vibrato, but on the violin this is negligible in comparison with the energy from bowing. On the guitar, vibrato has a dampening effect, causing the note to decay faster. Neil Paterson Wormit, Fife, UK
n Your correspondent is mishearing vibrato on stringed instruments. Classical vibrato, as used by violinists, involves Grout gripe rocking the finger back and Why does white bathroom grouting forth parallel to the string. turn black? And what can be done This alternately lengthens and to prevent it? shortens the vibrating string, producing a variation in pitch. n The black staining on the grout I suspect that rapid vibrato, especially, can give the impression is the fungus Aspergillus niger. It thrives in warm, damp areas, and of greater volume. The bow can the grout surrounding bathroom also be driven harder at the same tiles is an excellent habitat for it. time, which will produce an Applying neat bleach and actual volume increase. Guitarists also use classical “Traces of soap, shampoo vibrato. On the guitar, this has and cleaning agents are a the effect of increasing and rich diet for the fungi that then lowering string tension, blacken grouting” producing a change in pitch. Sideways vibrato, as used in blues bicarbonate of soda, then and rock playing, also stretches scrubbing with a toothbrush, and unstretches the string, with will remove the mould. a corresponding pitch variation. Unfortunately, the fungal cells However, guitars have frets, can penetrate mastic and leave unlike a violin, so vibrato cannot a permanent black stain. If that lower the pitch below that of the happens, the mastic will have to fretted note, whereas a violinist be gouged out and replaced. can move above and below the It is hard to prevent the fungus initial pitch. Blues and rock players can get a from appearing in the first place. The tiles need to be kept dry and true “up and down” pitch vibrato only when they have initially bent the bathroom must have good
The writers of answers published in the magazine will receive a cheque for £25 (or US$ equivalent). Answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. We are pleased to acknowledge financial support from Statoil in producing The Last Word. New Scientist retains total editorial control over the content. Reed Business Information Ltd reserves all rights to reuse question
and answer material that has been submitted by readers in any medium or in any format. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to lastword@newscientist. com or visit www.newscientist.com/topic/ lastword (please include a postal address in order to receive payment for answers). Unanswered questions can also be found at this URL.
aeration to reduce humidity levels. Regular bleaching of the tiles will also prevent any build-up of mould. Peter Scott Hove, East Sussex, UK Regular application of neat bleach seems to be the mainstay of readers’ grout-whitening methods. A couple of other tactics may be worth trying – Ed n Grout turns black when colonised by a fungus. The most common of the species that thrive on grout and bathroom sealants is Aspergillus niger. The microscopic spores are airborne and get everywhere, and the mould is very difficult to remove completely once established in a bathroom or shower cubicle. Bleach and strong detergents may kill the surface of the fungus but not remove the unsightly black staining. In a severe case, the only completely reliable way to remove the stains is to cut or scrape out the old grout and apply it afresh. The sealant will need to be replaced as well. There are products on the market that claim to be mould and fungus-resistant, but I have yet to find one that lives up to this promise. Over time, any such resistance diminishes, and in a few years the mould takes hold. The best strategy, once you have cleaned and regrouted the bathroom, is to prevent the spores germinating. Keep your bathroom or shower cubicle well ventilated. Install a good ceiling vent with an
extractor fan that stays running for at least 10 minutes after you have turned off the light, or whichever device triggers the fan. After using the shower, take a dry cloth and thoroughly wipe down all surfaces, particularly the sealant joint at the base. Once the bathroom is ventilated and dry, there is no home for the spores to settle in and cause you anguish. Simon Young Horwich, Lancashire, UK n The blackening of bathroom grouting is usually caused by fungal growth. It is there because the grout provides all it needs: a rough surface, humidity and food. It is easy to see how our bathrooms and showers provide the first two, but few people realise that traces of soap, shampoo and cleaning agents are a rich diet for fungi. I have found that I can substantially reduce the nuisance by frequent, careful washing of vulnerable surfaces with pure water. John King By email, no address supplied
This week’s question Backing up
I have a 25-litre rucksack that I use when on holiday. However, wearing it causes my T-shirt to ride up my back, which is rather annoying. Why does this happen and how can I prevent it? Donna Stein Birmingham, UK
The last word on energy Win £100 by answering our monthly question about energy issues Why do wind turbines have such thin blades? Would it not be more efficient for them to have wider blades in order to capture and convert more of the wind’s energy? Answers should reach us by 2359 BST on 15 September 2013 to [email protected] or visit www.newscientist.com/topic/ energy. Terms and conditions are also at this URL.
Last words past and present at newscientist.com/topic/lastword
sponsored by
String theory When string players use vibrato, the movement of their hands looks as if they are changing the point at which the string is stopped against the fingerboard. This should change the pitch of the note. But what I hear is not a pitch change but a change in volume. Am I misunderstanding what is going on?
the string sideways to give a new note. A sideways vibrato then gives notes both above and below this pitch. In theory, you can impart more energy to the string with vibrato, but on the violin this is negligible in comparison with the energy from bowing. On the guitar, vibrato has a dampening effect, causing the note to decay faster. Neil Paterson Wormit, Fife, UK
n Your correspondent is mishearing vibrato on stringed instruments. Classical vibrato, as used by violinists, involves Grout gripe rocking the finger back and Why does white bathroom grouting forth parallel to the string. turn black? And what can be done This alternately lengthens and to prevent it? shortens the vibrating string, producing a variation in pitch. n The black staining on the grout I suspect that rapid vibrato, especially, can give the impression is the fungus Aspergillus niger. It thrives in warm, damp areas, and of greater volume. The bow can the grout surrounding bathroom also be driven harder at the same tiles is an excellent habitat for it. time, which will produce an Applying neat bleach and actual volume increase. Guitarists also use classical “Traces of soap, shampoo vibrato. On the guitar, this has and cleaning agents are a the effect of increasing and rich diet for the fungi that then lowering string tension, blacken grouting” producing a change in pitch. Sideways vibrato, as used in blues bicarbonate of soda, then and rock playing, also stretches scrubbing with a toothbrush, and unstretches the string, with will remove the mould. a corresponding pitch variation. Unfortunately, the fungal cells However, guitars have frets, can penetrate mastic and leave unlike a violin, so vibrato cannot a permanent black stain. If that lower the pitch below that of the happens, the mastic will have to fretted note, whereas a violinist be gouged out and replaced. can move above and below the It is hard to prevent the fungus initial pitch. Blues and rock players can get a from appearing in the first place. The tiles need to be kept dry and true “up and down” pitch vibrato only when they have initially bent the bathroom must have good
The writers of answers published in the magazine will receive a cheque for £25 (or US$ equivalent). Answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. We are pleased to acknowledge financial support from Statoil in producing The Last Word. New Scientist retains total editorial control over the content. Reed Business Information Ltd reserves all rights to reuse question
and answer material that has been submitted by readers in any medium or in any format. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to lastword@newscientist. com or visit www.newscientist.com/topic/ lastword (please include a postal address in order to receive payment for answers). Unanswered questions can also be found at this URL.
aeration to reduce humidity levels. Regular bleaching of the tiles will also prevent any build-up of mould. Peter Scott Hove, East Sussex, UK Regular application of neat bleach seems to be the mainstay of readers’ grout-whitening methods. A couple of other tactics may be worth trying – Ed n Grout turns black when colonised by a fungus. The most common of the species that thrive on grout and bathroom sealants is Aspergillus niger. The microscopic spores are airborne and get everywhere, and the mould is very difficult to remove completely once established in a bathroom or shower cubicle. Bleach and strong detergents may kill the surface of the fungus but not remove the unsightly black staining. In a severe case, the only completely reliable way to remove the stains is to cut or scrape out the old grout and apply it afresh. The sealant will need to be replaced as well. There are products on the market that claim to be mould and fungus-resistant, but I have yet to find one that lives up to this promise. Over time, any such resistance diminishes, and in a few years the mould takes hold. The best strategy, once you have cleaned and regrouted the bathroom, is to prevent the spores germinating. Keep your bathroom or shower cubicle well ventilated. Install a good ceiling vent with an
extractor fan that stays running for at least 10 minutes after you have turned off the light, or whichever device triggers the fan. After using the shower, take a dry cloth and thoroughly wipe down all surfaces, particularly the sealant joint at the base. Once the bathroom is ventilated and dry, there is no home for the spores to settle in and cause you anguish. Simon Young Horwich, Lancashire, UK n The blackening of bathroom grouting is usually caused by fungal growth. It is there because the grout provides all it needs: a rough surface, humidity and food. It is easy to see how our bathrooms and showers provide the first two, but few people realise that traces of soap, shampoo and cleaning agents are a rich diet for fungi. I have found that I can substantially reduce the nuisance by frequent, careful washing of vulnerable surfaces with pure water. John King By email, no address supplied
This week’s question Backing up
I have a 25-litre rucksack that I use when on holiday. However, wearing it causes my T-shirt to ride up my back, which is rather annoying. Why does this happen and how can I prevent it? Donna Stein Birmingham, UK
The last word on energy Win £100 by answering our monthly question about energy issues Why do wind turbines have such thin blades? Would it not be more efficient for them to have wider blades in order to capture and convert more of the wind’s energy? Answers should reach us by 2359 BST on 15 September 2013 to [email protected] or visit www.newscientist.com/topic/ energy. Terms and conditions are also at this URL.