I will be adding to this post.
Vinegar "is essentially a 5-8% solution of acetic acid in water." However, "diluted acetic acid is not vinegar". All vinegars used as hair or skin rinses need to be well diluted. You can buy pH test strips to read the final pH result. The pH of undiluted vinegar straight from the bottle is on average, between 2-3. Products with a pH of below 3.5 can be damaging to hair and skin, depending on how much is used, how it is used (leaving it in the hair as opposed to rinsing it out for example), and how often it is used. See also this article and updated - this blog post.
Acetic acid is an alpha hydroxy acid.
"Alpha Hydroxy Acids", 2015, @
"How can AHAs be used safely?
... The final product has a pH of 3.5 or greater."
A vinegar rinse can help remove some natural product residues, soap scum and hard water minerals from hair. It cannot chelate metals like iron or copper, nor can it replace a clarifier to remove conventional hair product build-up (residue). Its acidity can help keep hair cuticles smooth and aligned and make the hair shiny. It can be used to reacidify the skin following washing with an alkaline soap. It has been demonstrated to have antibacterial properties. However, that does not make it a health cure, or the only cleaning solution to be used for other purposes.
With genuine or true vinegars, the flavours and aromas come from the acetic acid source.
Any vinegar that is not white or clear has the potential to alter or stain hair colour somewhat. Such stains are not permanent but can be difficult to remove, depending on how dry and porous the hair may be.
Apple Cider Vinegar (ACV)
At a 5% acetic acid content and used well diluted, as with any typical vinegar used on hair or skin, apple cider vinegar acts the same as the others. It can add a red tint to hair. It is the acetic acid that is working to close the cuticles and smooth the hair, even with the mother in organic ACV being touted to do more. Mother of vinegar is a term used to refer to the mass of bacteria scum that forms on top of cider when alcohol turns into vinegar. The pH of ACV is about 3.1, e.g. Bragg ACV, "pH = 3.075"
"The truth about 'miracle foods' -- from chia seeds to coconut oil", 2015, color and bolding added by me, @
“EFSA is very clear ... very strict ... what health messages it allows companies to use in the marketing ... Apple Cider Vinegar ... anecdotally linked with ... potential health benefits in areas including: digestive disorders, sore throats, high cholesterol, indigestion, preventing cancer, dandruff, acne, energy boosting, cramps, and helping with blood sugar control. The EFSA ... hasn’t approved any of these claims. Many of the studies have been on animals or in laboratories using human cells." -UNPROVEN! EFSA (European Food Safety Authority)
"Functional Properties of Vinegar", 2014, color and bolding added by me
"daily intake of vinegar may affect human health and metabolism. Further studies related to health effects of vinegar consumption by humans are necessary." - Lots of studies for this conclusion -UNPROVEN! - The EFSA is quite correct!
"Veterinarian dismisses apple cider vinegar claim" - The Western Producer", 2015, color and bolding added by me, @
"apple cider vinegar ... choosing ... it instead of a scientifically proven product can have deadly consequences." That sums it up about ALL quackery - direct and indirect harm can be and often is - fatal.
Genuine malt vinegar has no added sugar or other additives. With an acetic acid content of 5% (the usual percentage of most vinegars not for specialty use like pickling), it will work on hair like white vinegar or apple cider vinegar or any other true vinegar with that percentage and no additives. Heinz malt vinegar "Ingredients: Malt Vinegar (Barley, corn malt), diluted with water to 5% acidity." In this case it is not a purely barley malt vinegar but it is a genuine malt vinegar and is suitable for cosmetic use.
One needs to read labels carefully. There are immitations labeled malt vinegar that do have additives. Vinegars with higher percentages of acetic acid, can need to be very diluted for cosmetic use, much more so than the average vinegar at 5% acetic acid content. Concentratied acetic acid is corrosive. Wiki on acetic acid is a good source of information and well referenced.
"barley is malted ... soaked in water and allowed to germinate before being roasted ... partial germination and roasting converts the natural starch in the barley into ... maltose. ... malted barley is fermented ... maltose will convert to alcohol. ... the alcohol turns to vinegar ... some companies make immitations of this popular vinegar ... dyed with ingredients like caramel ... "
True balsamic vinegar has no added sugar either. Heinz balsamic vinegar "Ingredients: Burgundy wine vinegar dilute with water to 5% acidity, sulphur dioxide added to wine to protect color." A preservative was added to preserve the colour only.
Traditional balsamic vinegar is not considered to be the same as wine vinegar. Wiki is a good source on this too.
"Traditional balsamic vinegar is produced from the juice of just-harvested white grapes (typically, Trebbiano grapes) boiled down to approximately 30% of the original volume to create a concentrate or must, which is then fermented with a slow aging process which concentrates the flavours. The flavour intensifies over the years, with the vinegar being stored in wooden casks, becoming sweet, viscous and very concentrated."
Balsamic vinegar has been reported to work well on hair on the Long Hair Community boards, with no discernable difference to using other vinegars more typically used. Other than a possible preservative for colour it can be as basic as any other vinegar. The acetic acid content is what one needs to be most concerned about.