[Doug Holloway]

Hi Guys,

The other day I cleaned a cream suite , probably a mixture of synthetics and natural.

There were a number of very well entrenched red wine stains.

I sprayed with microsplitter which turned the red into a very dark green.

I tried a number of different approaches but it was evident that these marks were unlikely to be removable .

As the green looked much worse than the red I used neat acid rinse which  turned  the stain back to red.

I then tried a much stronger acid , rust remover, which turned the green into a very bright pink.

I then used dilute cleaning solution to turn it back red.

I think what is going on is that the dye , which is effectively what the red wine is now , is pH sensitive , where it's oxidation state changes with pH.

This got me thinking about Dave's colour change problem which may well be related.

Has anyone else experienced these pH related colour changes?

Cheers,

Doug

[Dynafoam]

Doug,

I have encountered 'indicator dyes' in wine quite often. Australian and South American wines seem to be the most common culprets and blue is another colour shown.

What I do find is that when this shows, making gentle swings up and down the pH scale, with rinses in between, often produces lighter shades of each colour.

Of the red wine stains that I have not completely removed, this type features highly.

[stu_thomson]

had this on a suite yesterday, customer tried to get out red wine on suite i tried solution spotter it turned blue then used alltec tea an coffee remover and it vanished immedietly, one happy customer. phew!

[nick p]

yes ive seen it go green before with alltec red wine stain remover rinse sent it back red but could not get the wine out completely  red fruit juice remover did fade it though cant remeber who it came from was a few years ago i had that one

nick

[Ian Gourlay]

Somthing else to worry about

[*paul_moss]

John would you explain a little bit more about indicator dyes.
I understand what they are but not the chemical change that take place.

Regards
Paul

[Doug Holloway]

Paul,

John is referring to dyes which change colour with pH such as those contained in pH papers .

These reactions are reversible just like my red wine / green wine stain.


What i believe happens is that transition metals can exist in different oxidation states and can move from one to the other and back again.

e.g iron as ferric (2) to ferrous(3)

When we are attempting to clean we may cause this , which I believe is the most likely expalanation for Dave's colour change suite.It may be that microsplitters are much more likely to cause this.

Please bear in mind it was over 20 years ago since I covered this and it would be useful if the NCCA for example had a technical dept which could research this with dye manufacturers/ upholstery manufactures.

Cheers,

Doug

[*paul_moss]

Doug thanks for the reply.
Gives a better understanding of what takes place.
Why do you think that m/s would cause it to happen more than other chemicals ? or have I just missread your comments
Paul

[Dynafoam]

Doug,

I think that the FeO/FeO₂ is one posible cause of the colour change.

More likely still it is due to the presence of anthocyanin (blue) and flavonol (yellow), two plant dyes that act much the same as litmus paper.

The effect of these dyes can be seen in the living plant - a hydrangea growing in an acid soil will produce pink flowers, but if the soil is made more alkaline the flowers will be blue.
The dye responsible in this example is anthocyanin.

Another example of natural indicator dyes can be seen in cherry juice, which may be red (pH = 2.5), orange (pH = 4.5), brown (pH = 7), or green (pH = 10). Dyes found in red cabbage react in a similar manner. Yet another is the dye found in the dreaded turmeric, which is commonly seen as the bright yellow of curry stain, but can be turned pink by the addition of a base solution.

With all these the relevant factor is whether the prevailing conditions are acid or base.

Clearly wines are complex compounds, so the simple dye colour change/ pH relationship does not follow the same rules as with the raw dye, but my experience tends to support the theory.

These colour changes can be seen without the involvement of micro-splitters, but it may be that other actions associated with the splitting of soils make these changes more apparent.

I hope that this also goes some way to answering both of Pauls' questions

[*paul_moss]

John answered absolute

Many thanks Paul

[Doug Holloway]

Paul,

The only reason I mention microsplitters is that Dave had never had this problem before and he used one,  and the colour change I experienced was also much worse with m/s than when I tried to do the same with detergents.

When I worked as a chemist a significant amount of time was spent problem solving with current products , and the first thing you learnt to do was to check what had changed.
Quite often manufacturers would make changes without telling you and this would be where the problem lay.


This does'nt mean M/S are the cause of the problem but it would be prudent to keep a close watch on this type of thing.

I will do some research on transition metal dyes and post it if I come up with anything interesting.

Going for a beer now ,

Cheers,

Doug