Strange stain in caravan

This topic has 11 replies, 9 voices, and was last updated 24 August 2021 at 09:35 by Peter G. Shaw.

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20 August 2021 at 11:53 #559100
Peter G. Shaw
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@peterg-shaw75338
Hi folks,

I'm looking for ideas on what may have caused some strange dark(ish) grey stains in the mugs and the kitchen sink of our caravan.

Caravan used 1st 2 weeks of June in Scottish Highlands – no problems at all.

Used again 1st 2 weeks of August in Gargrave (near Skipton in N. Yorks.) and a dark(ish) grey stain has appeared in our melamine mugs and in the kitchen sink. It is not apparent on any other plates/bowls (also melamine) nor has it appeared in the other sink, or in the shower unit (although the shower hasn't been used that much).

The mugs have been stained by the usual tea/coffee stains and cleaned with Puriclean as was the water system: in both instances this was before the June holiday.

One thought is that the Gargrave water is, I'm told, quite hard whilst the Scottish water I think is quite soft. But we've been to Gargrave before with no ill effects.

Another thought is that the same bottle of green Fairy washing up has been kept in the caravan for a few years now. Can it have deteriorated? In which case why aren't the plates & bowls stained?

Any thoughts?

Peter G. Shaw
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20 August 2021 at 11:53 #36529
Peter G. Shaw
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@peterg-shaw75338
20 August 2021 at 16:08 #559148
larry phelan 1
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@larryphelan1
Could be due to an infected Haggis getting revenge.

Other than that I dinna ken.
20 August 2021 at 16:35 #559153
Steviegtr
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@steviegtr
I guess there could be a lot of iron in the Gargrave water. Cannot explain why it's not effected everything though.

Steve.
20 August 2021 at 17:06 #559155
Dave Halford
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@davehalford22513
Tea has tannin in it. Iron and tannin = blue black like steel nails or screws in oak.
20 August 2021 at 17:33 #559157
Tim Stevens
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@timstevens64731
Pottery and porcelain have a different chemical structure from melamine – glassy rather than plastic. So, it is likely that whatever the cause of the stain, the effect on melamine is likely to be different from more conventional (less 20th century) eating ware. Just a thought.

There is a lot of limestone around Gargrave, and hard water is known to leave deposits here and there. If it happens very regularly it produces stalactites and stalagmites. So look out.

Regards, Tim
20 August 2021 at 18:46 #559167
pgk pgk
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@pgkpgk17461
Periods either of prolonged drought or of heavy rain can both lead to water supply contamination.
If it is due to hard water then a vinegar soak should shift it.

pgk
20 August 2021 at 18:55 #559172
Rik Shaw
Participant
@rikshaw
I have just glanced through the results of a study entitled “The Pathological Effects of Melamine and Cyanuric Acid in the Diet of Walking Catfish” in which it records that said catfish fed on a diet of cyanuric acid and melamine displayed skin darkening (staining) within three days.

I would not suggest for one moment that cyanuric or even uric acid is finding its way into your sink – but if it – is this might explain the staining on your mugs.

Rik
20 August 2021 at 21:12 #559186
Peter G. Shaw
Participant
@peterg-shaw75338
Some answers.

As far as I know, all the mugs, plates & bowls are melamine. They even have the same pattern on the outside. I assume therefore that they are all the same material. Incidently, we also have some "plastic" glasses. I say "plastic" because I don't know what they are made of, except that they are visually clear and lightweight. No staining on these.

The kitchen sink is also "plastic", but I don't know what sort of "plastic".

I'll try the vinegar soak idea tomorrow – if we've enough that is – and report back.

Cyanuric/uric acid. Don't know how to prove that.

Iron in the water. There is a rather funny tailpiece about that. Unfortunately, I am on chemotherapy, and have been for 2 years now. Starting from 2 years ago, my haemaglobin level has gradually dropped such that the medics are now somewhat concerned and rather comically the last 6 readings have been 113, 111, 109, 103, 106, 113. That last reading was taken the day after we came back from Gargrave. Which makes me wonder!

Oh, & by the way, yes we do have a reasonably quantity of tea!

Many thanks for the thoughts, I'll report back.

Peter G. Shaw
20 August 2021 at 21:23 #559189
Howard Lewis
Participant
@howardlewis46836
If gentle methods fail, try bleach (Sodium Hypochlorite ) removes tannin stains from tea pot and mugs very well!

You only need a few drops to roll around and the stain disappears almost before your eyes.

Howard
20 August 2021 at 23:45 #559199
duncan webster 1
Participant
@duncanwebster1
The stuff used for cleaning false teeth is reputed to shift tea stains and not leave everything tasting of bleach. Can't vouch for it as I still have most of my own gnashers
24 August 2021 at 09:35 #559613
Peter G. Shaw
Participant
@peterg-shaw75338
Final (rather late) update.

Vinegar didn't touch the mug I tried it on, but since we were considering replacing them anyway (something like 25 years old, and one had splintered somehow internally) it's no real loss.

In respect of the sink, I used a cream cleaner originally from ASDA but really quite ancient (I believe it came with our previous s/h caravan, so could be around 25 years old) and along with a modicum of elbow grease, the stains were mostly removed. What's left is ok as the sink is not a single colour, but rather a faint mix of light colours. So thankfully, all's well now.

Thanks for all the thoughts.

Peter G. Shaw

p.s. Duncan, I do have a set of false teeth, and when I was given them (it) I said to the dentist "I suppose that means getting some Steradent now." The reply was "Oh no, don't bother with that, just use ordinary toothpaste – it's plenty good enough!" So that's what I've used ever since.
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