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Iain Smellie @iainsmellie.bsky.social · 25/01/2026

Just been to the supermarket and spotted some ready prepared red cabbage indicator #Gardenindicators

Reposted by Iain Smellie

Julian R. Silverman @manhattanscientist.bsky.social · 07/11/2025

#gardenindicators in action: testing to see if our student’s soap is safe for the skin #gardenindicators in print: How to find acids with flowers: Robert Boyle’s ‘syrrup of violets’ and the chemistry of color indicators link.springer.com/article/10.1...

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Iain Smellie @iainsmellie.bsky.social · 30/11/2025

Seasonal #Gardenindicators time. The bramble whiskies are ready! There’s a sweet one (made from Grants) and a more fiery one (made from famous grouse). Both tasty 🙂

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Reposted by Iain Smellie

Julian R. Silverman @manhattanscientist.bsky.social · 16/10/2025

Soap soap soap + cabbage indicators.

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Iain Smellie @iainsmellie.bsky.social · 15/10/2025

It isn’t all #Gardenindicators in our lab, we’ve been making our own phenolphthalein’s too. They are different colours and pleasingly, all worked well in an acid/base titration. #Chemsky

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Iain Smellie @iainsmellie.bsky.social · 05/10/2025

Further tinned fruit results today, mixing the juice from tinned peaches with bramble extract gives a beautiful purple colour! The left glass contains a mixture of bramble juice, tinned peach juice and water. The right glass contains diluted bramble juice. #Gardenindicators #Chemsky

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Reposted by Iain Smellie

Julian R. Silverman @manhattanscientist.bsky.social · 19/09/2025

🤩 amazing! Thank you Starbucks for raising the price of the passion tea to inspire my making it at home. This will be a fun addition to our exploration of mordants!

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Iain Smellie @iainsmellie.bsky.social · 19/09/2025

@manhattanscientist.bsky.social has inspired a nice #Gardenindicators experiment! The samples below, all contain Hibiscus tea. L to R, tea, tea with pineapple juice from a tin can, tea with acetic acid and tea with HCl. Those tin ions make a lovely purple complex with anthocyanins!

Hibiscus tea samples. Left to Right: freshly brewed tea, tea with pineapple juice from a tin can, tea with acetic acid and tea with dilute HCl. The purple colour likely comes from complexation of the tin ions with anthocyanins from the hibiscus flowers.

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Reposted by Iain Smellie

Julian R. Silverman @manhattanscientist.bsky.social · 19/09/2025

My colleague Marko Jeran turned me onto this electrolysis demonstration using our cabbage indicator. #anthocyanin #redox #acidbase

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Iain Smellie @iainsmellie.bsky.social · 31/08/2025

This seems to becoming a tradition for the end of August. Bramble whisky round 2 now in progress. A double batch this time as well. #Gardenindicators I look forward to the end of November when they will be ready. One jar contains famous grouse, the other is grant’s triple wood blend. #chemsky

2 Kilner jars with whisky, sugar and brambles. These will be left for 3 months before the berries are filtered out.

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Iain Smellie @iainsmellie.bsky.social · 14/08/2025

Plenty of beautiful Hydrangeas around St Andrews now. Some will hopefully get used as #Gardenindicators in teaching next year.

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Iain Smellie @iainsmellie.bsky.social · 10/07/2025

Anyone who has tried making naphtholphthalein will have encountered this compound at some point.

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Iain Smellie @iainsmellie.bsky.social · 19/05/2025

It has been a while, but another #Gardenindicators video is now ready. This one shows a cheap and cheerful way to extract blackberries, works for raspberries too. youtu.be/HIV1Tgpa1-g?...

youtu.be

Anthocyanin Extraction: Blackberries (Brambles)

YouTube video by Gardenindicators

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Reposted by Iain Smellie

Elizabeth Cerkez @zekrec.bsky.social · 14/05/2025

Alright, this is an awesome experiment - complexation, solubility, indicator acid/base, it’s got everything!! pubs.acs.org/doi/10.1021/...

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Iain Smellie @iainsmellie.bsky.social · 07/03/2025

I got a nice #Gardenindicators gift this week from @AlchemistAngus. A can of crushed pineapple! The anthocyanins in blackberry extract can be used to detect dissolved tin(II) ions in the pineapple juice. The anthocyanin/tin complexes give a lovely purple colour! #Chemsky

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Reposted by Iain Smellie

Compound Interest | Chemistry infographics @compoundchem.com · 23/12/2024

This month #PeriodicGraphics in @cenmag.bsky.social is a whole decade old! To mark the anniversary, here's a graphic on some of the interesting properties and uses of tin, the metal that traditionally marks tenth anniversaries: cen.acs.org/materials/Pe... #ChemSky 🧪

Infographic on tin. Tin has 10 stable isotopes, the most of any element. The β-tin allotrope is stable at and above room temperature. It transforms into brittle α-tin at 13.2 ˚C, or lower with impurities.  Some historians claim that in 1812, the cold transformed the tin buttons on uniforms in Napoleon I's army to crumbly α-tin, contributing to the army's defeat. No eyewitness accounts to support this claim.  Modern 'tin' cans are made of stainless steel. Manufacturers used to use a thin layer of tin plate to prevent corrosion. But today, many cans have a plastic coating instead—often bisphenol compounds.  Many toothpastes use stannous fluoride, a source of fluoride and tin ions. Fluoride ions help prevent tooth decay, and tin ions help prevent gingivitis and tooth sensitivity.  Dibutyltin dilaurate stops oxidative degradation in polyvinyl chloride (PVC) and some other plastics.  The LHC’s superconducting niobium-tin magnets focus proton beams to increase the particle collision rate.

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Iain Smellie @iainsmellie.bsky.social · 18/12/2024

We’ve made a lot of phenolphthaleins this year, so here is a multiple phenolphthalein #Chemistree #OChemistree that uses many of the compounds we made. Also featuring an illuminated fluorescein bauble at the top. All planned and made by our lab office team! (not on this platform yet).

A list of all the phenolphthaleins will be added later.

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Iain Smellie @iainsmellie.bsky.social · 16/12/2024

In an earlier post I showed a range of colourful #Gardenindicators oxalis samples. bsky.app/profile/iain... Much later than I intended, I have finally managed to get the video version on YouTube! youtu.be/JoefItjibOY?....

youtu.be

Oxalis Anthocyanins - Part 1

YouTube video by Gardenindicators

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Iain Smellie @iainsmellie.bsky.social · 15/12/2024

I tried a different type of #Gardenindicators experiment earlier this year. I started making bramble whisky in the late summer, this is the finished version after 3 months. Nice colour, quite a sweet taste, a bit like sloe gin. #Chemsky

Bramble whisky. I made this by soaking brambles (blackberries) in a bottle of whisky and added some sugar. I then let the mixture soak for just over 3 months.

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Iain Smellie @iainsmellie.bsky.social · 08/12/2024

At this time of year the number of available #Gardenindicators is more limited. However, we’ve been making some classic pH indicators too. Interesting range of colours in the methyl phenolphthalein series #Chemsky youtu.be/lcHvVRApqaQ?...

youtu.be

Colourful Phenolphthalein pH Indicator Selection

YouTube video by Gardenindicators

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Iain Smellie @iainsmellie.bsky.social · 01/12/2024

2 years ago, @AlchemistAngus grew some purple carrots in our teaching lab. Remarkably, the dried carrots are still providing extracts 2 years later! Colourful #Gardenindicators results here youtu.be/0oNgtucj2Ak?...

youtu.be

Purple Carrot Anthocyanins - Winter 2024

YouTube video by Gardenindicators

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Iain Smellie @iainsmellie.bsky.social · 30/11/2024

Hydrangeas are a #Gardenindicators favourite, although the blue ones can be difficult to get extracts from. In this video, red hydrangea extract mixed with metal salts provides some colourful results. youtu.be/27nrO-4DEgg?...

youtu.be

Colourful Complexes: Hydrangea Colours-Updated

YouTube video by Gardenindicators

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Iain Smellie @iainsmellie.bsky.social · 26/11/2024

Thank you very much to @AlchemistAngus (on another platform currently) for this stunning #Gardenindicators specimen. We now have a lab oxalis to join our poinsettia! A video will appear on YouTube soon. #Chemsky

Left to Right, oxalis extract mixed with: dilute HCl (pink) ammonium acetate (violet), sodium bicarbonate (blue) and dilute NaOH (yellow).

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Reposted by Iain Smellie

CrocodileChemist @crocodilechemi1.bsky.social · 24/11/2024

Here’s the pH evaluation of a red sweet pea from my garden. A cheeky blue around pH 8-10 is always a bonus! #GardenIndicators

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Iain Smellie @iainsmellie.bsky.social · 23/11/2024

There was a good crop of brambles this year, plenty of fruit for #Gardenindicators experiments. I made "Maraschino" style brambles by soaking them in bisulfite solution, then soaking them in a dye/sugar solution. This process is similar to the method used to make cocktail cherries. #Chemsky

A berry being soaked in sodium metabisulfite, a useful source of bisulfite ions.

A berry soaked in sodium metabisulfite overnight becomes bleached. The berry anthocyanins are converted to colourless bisulfite adducts.

The top berry has been bleached and dried. The left berry has been soaked in a sugar solution containing crystal violet. The right berry has been soaked in a sugar solution containing brilliant blue FCF. Cocktail cherries are made using different types of red dyes. I didn't get them to work in this case.

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Reposted by Iain Smellie

Andres Tretiakov @andrestrujado.bsky.social · 22/11/2024

Happy #FluorescenceFriday 😁 Following @compoundchem.com great post last week, here is another easy one. Extraction of highly fluorescent aesculin from the bark of horse chestnut twigs. Aesculin fluoresces a beautiful blue under UV illumination. #RealTimeChem SCHOOL #TECHNICIANSMAKEITHAPPEN

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Iain Smellie @iainsmellie.bsky.social · 21/11/2024

A few weeks ago, I put about 100 dried red geraniums in a Soxhlet extractor. After an hour or so, hot methanol gave a very rich red anthocyanin-containing extract. Hopefully, some pelargonidin will be isolated from this soon #Gardenindicators #chemsky

Packed Soxhlet extractor before hot methanol started to flush through.

The geraniums after about 60 minutes of soaking in hot methanol, a lot of the red colour had gone by this time.

The rich red residue after the methanol extract was concentrated using a rotary evaporator. This has now been cooled in a fridge to see if any crystals appear!

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Reposted by Iain Smellie

Compound Interest | Chemistry infographics @compoundchem.com · 21/11/2024

It’s a great project – there’s a whole crowd-sourced spreadsheet of indicators and colours here from @crocodilechemi1.bsky.social: docs.google.com/spreadsheets...

docs.google.com

#GardenIndicators

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Reposted by Iain Smellie

Teresa Marx @teresamarx.bsky.social · 20/11/2024

#IteachChem 🥽 Chemistry and art: Students are investigating the effect of pH on dye color. I’m obsessed with the bright orange from annatto seeds!

An array of dyed fabric swatches show color differences at neutral, low, and high pH ranges. Dye sources include cochineal, turmeric, madder, annatto, purple corn, and red cabbage.

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Iain Smellie @iainsmellie.bsky.social · 20/11/2024

The poinsettia I got last week resulted in some good #Gardenindicators colour changes in acid, base and with some metal ions too. youtu.be/1xE3DFqbjSw?... not bad from a £2.50 flower from the clearance shelf in the supermarket.

youtu.be

Poinsettia Anthocyanins - Winter 2024

YouTube video by Gardenindicators

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Iain Smellie @iainsmellie.bsky.social · 18/11/2024

One of the things I learned about from #Gardenindicators on the old platform was the Shinoda test for plant flavonoids. Here are rutin and quercetin mixed in HCl and ethanol, then magnesium granules were added. These tests can be very colourful!

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Reposted by Iain Smellie

Ariel Serkin @aserkin.bsky.social · 17/11/2024

My HS food chemistry elective has made indicators in the past but yours are stunning!

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Reposted by Iain Smellie

David ALBERTO @astrolabe-science.fr · 17/11/2024

Fluorescence of quinine in 'tonic' water and sodas. 🎢 🧪 #iTeachChem #Chemsky Max absorption in UV light, max emission in blue. Picture & plot made for last year's science fair.

Photo of a large bottle of tonic soda next to a black UV lamp. The soda is glowing blue (fluorescence).

Absorption and emission spectrum of quinine, with UV and visible domains labeled. The absorption's maximum is around 350nm and the emission's maximum arond 450nm.

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Reposted by Iain Smellie

CrocodileChemist @crocodilechemi1.bsky.social · 17/11/2024

The #GardenIndicators project started during the first lockdown as an accessible project from home. Anthocyanins are generally pretty easy to extract… but there are a few tricky ones!

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Iain Smellie @iainsmellie.bsky.social · 17/11/2024

Thank you very much @crocodilechemi1.bsky.social for the purple runner beans you sent, they gave very nice #Gardenindicators colours! The low pH pink is beautiful. This is the first video I have made that shows the extraction of the plant material. youtu.be/o7GpWCL6guk?...

youtu.be

Anthocyanin Extraction: Purple Runner Bean

YouTube video by Gardenindicators

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Reposted by Iain Smellie

CrocodileChemist @crocodilechemi1.bsky.social · 16/11/2024

Here’s the pH evaluation of a pink & white geranium from pH 1 to 13. The bottom image shows an RGB reaction plot, using actual RGB values to produce an image of the dynamic neutralisation reaction. Lovely purple with Al³⁺ ions too💜#GardenIndicators

Anthocyanin extracts from the flower are added to different pH solutions to produce different colours - red in acid, blue/purple neutral and green/yellow alkali

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Iain Smellie @iainsmellie.bsky.social · 15/11/2024

I managed to get a poinsettia for # Gardenindicators purposes. Changing the pH leads to colour changes. Some anthocyanin-containing extracts change colour with metal ions too. In this case, alum solution on the left and tin(II) chloride on the right.

A handful of poinsettia leaves were soaked in hot water and then about 2 mL of extract was added to a saturated solution of alum (left) and a solution containing tin(II) chloride (right).

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Compound Interest | Chemistry infographics @compoundchem.com · 15/11/2024

#FluorescenceFriday reminder that if you sprinkle turmeric into alcohol while shining a UV light on it, you get a brilliant fireworks display in a glass 🎇 #ChemSky 🧪

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Iain Smellie @iainsmellie.bsky.social · 13/11/2024

I’m seeing poinsettias in the shops now, these make great #Gardenindicators! but they can change colour other ways too youtu.be/xpFA3wMbxOA?...

youtu.be

Anthocyanin Bleaching: Poinsettia

YouTube video by Gardenindicators

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Iain Smellie @iainsmellie.bsky.social · 12/11/2024

As well as #Gardenindicators experiments, since June we’ve been making some the more unfamiliar phenolphthalein-derived pH indicators. So far the colour range is pink to teal youtu.be/ySd5xmq4L0A?...

youtu.be

Colourful Phenolphthalein pH Indicators!

YouTube video by Gardenindicators

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Iain Smellie @iainsmellie.bsky.social · 09/11/2024

If anyone uses #Gardenindicators in teaching, videos of various fruit, flowers and vegetables are posted here www.youtube.com/@Gardenindicators/videos. They are there for any teachers/educators to use. Not just plants, there are some classic pH indicators there too.

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