Sciencemadness Discussion Board

indelible marking of citrus peel

picklewi - 27-11-2012 at 13:44

given the waxy surface and oil content of orange and other citrus peel it is very hard to mark these fruit indelibly.
I was beginning to lean toward tattooing them. Initially thinking of ballpoint ink but believed that I would have a problem cleaning away surplus ink. Then thinking to try with a gelatine/silver chloride solution but would look at any other suggestions

Oscilllator - 27-11-2012 at 21:32

wait why do you need to mark oranges indelibly?

Endimion17 - 28-11-2012 at 04:19

Obviously because his oranges are tough and have an alternative lifestyle.

Mailinmypocket - 29-11-2012 at 08:11

Have you tried solvent based permanent markers such as sharpies?

malcolmf - 29-11-2012 at 10:25

Tattooing with India Ink? Water-based, any surplus should easily wash off the waxy outer peel. (Specifically, I'm thinking of the ink used in Rotring pens--I assume someone still uses them so the ink would still be available...)
That's black only, though. If all else fails, ask a friendly tattooist where to get actual tattooing ink, which would give you a choice of colours and should be non-toxic.

Mailinmypocket - 29-11-2012 at 16:50

Actually... Why ARE you wanting to write in citrus fruit? Are you selling them and want to indicate the price? Is it an experiment where you need to identify the citrus specimens? What about just sticking labels on them or pinning tags to them?

Siggebo - 30-11-2012 at 00:21

Wash them with something nice, like acetone, and then apply a solvent based permanent marker?

paulr1234 - 30-11-2012 at 01:11

When I was a nipper in the UK, I seemed to remember oranges that were somehow marked with purple ink, a small stamp presumably done by the supplier or supermarket for some reason.

Morgan - 30-11-2012 at 19:40

"Indelible ink sunkist" search results
http://books.google.com/books?id=natMAAAAYAAJ&pg=PA885&a...

picklewi - 4-12-2012 at 12:55

thanks for the suggestions so far -- for your edification I am asking because I wish to write / decorate the orange and then peel it to note the disruption in the text/decoration. The release of oils in the torn skin tend to smudge the inks I have tried.

Since you ask, I wanted to be a chemist when young (and hence I love this site), I was later a mathematician and now I'm some kind of artist.

SM2 - 5-12-2012 at 08:14

There is one thing which seems to Remove almost everything. Even baked on inks, but'tis unfortunately not for sale anymore.
The Product was called "Remove", and under the main title it said either acetone free, or free acetons.
was sold by Gina, and sold in beauty product stores for over 1 year.

Not having that, I'd imagine nitromethane would be a great solvent.

zed - 6-12-2012 at 15:50

Treat them like cows. With a hot,hot,hot...branding iron. Or, do you have a laser?

Morgan - 23-12-2012 at 20:20

Quote: Originally posted by picklewi  
thanks for the suggestions so far -- for your edification I am asking because I wish to write / decorate the orange and then peel it to note the disruption in the text/decoration. The release of oils in the torn skin tend to smudge the inks I have tried.

Since you ask, I wanted to be a chemist when young (and hence I love this site), I was later a mathematician and now I'm some kind of artist.


I was toying with a grapefruit and seeing if it would hold a static charge and happened across this image on Google. It's nothing great but an artistic statement of some sort using ink on citrus. I noticed he has a bit of a smudging effect too in the last shot, the ink not sticking. As an aside, my "Leyden jar" grapefruit will arc over to my knuckle almost 5 cm. Maybe some metalic ink would help. ha
https://s3.amazonaws.com/imgspark.com/images/l/f0e8de664f78c...

Morgan - 19-1-2013 at 11:03

Here's something called Red 2 you might use on a lemon or grapefruit I don't know. Or if your orange wasn't orange enough to begin with. Probably a blue or green would be more pleasing of course.
http://en.wikipedia.org/wiki/Citrus_Red_2
http://littlelocavores.blogspot.com/2011/02/when-orange-isnt...
http://www.omg-facts.com/view/Facts/43999

Reactivity Profile
CITRUS RED NO. 2 is an azo compound. Toxic gases are formed by mixing compounds containing azo groups with acids, aldehydes, amides, carbamates, cyanides, inorganic fluorides, halogenated organics, isocyanates, ketones, metals, nitrides, peroxides, phenols, epoxides, acyl halides, and strong oxidizing or reducing agents. Flammable gases are formed by mixing materials in this group with alkali metals. Explosive combination can occur with strong oxidizing agents, metal salts, peroxides, and sulfides.
http://cameochemicals.noaa.gov/chemical/20040

SUMMARY OF THE INVENTION
"The appearance of the printed image must not bleed, disappear, fade, or transfer to other fruit placed in contact therewith, under any of the conditions and environmental changes thatfruit may encounter. For example, FD&C Blue #1 (CI Number 42090) is a major colorant in making violet or blue citrus inks. However, its sensitivity to water makes a printed image formed therefrom on citrus "bleed" when condensation occurs without theproper added ingredients. This is true to varying degrees with all FD&C dyes, due to their water solubility."
"Surprisingly, it has been discovered that ink jet ink compositions can be formulated to contain a non-water-soluble dye, such as Citrus Red #2 (C.I. solvent Red 80), which when used at an appropriate concentration, can provide a readable,water-resistant message on oranges and other fruit, as well as vegetables. Presently, Citrus Red #2 is used to color the skins of oranges that are not intended to be used for processing. The carrier medium for the colorant comprises a lower alcohol,such as ethanol, optionally in combination with a denaturing agent, such as methanol, and acetone."
http://www.patentgenius.com/patent/5637139.html

[Edited on 19-1-2013 by Morgan]

WolfPack - 3-2-2013 at 10:53

What about a 9B pencil and some kind of lacquer or acrylic resin on spray? There are sprays for protecting paints with a thin, flexible and transparent layer, for sanguine or chalk drawings.

Also, a laser is a great idea, as a laser mark can be very precise and not as coarse as a pencil, by using a lens. Most keychain lasers won't work but they can be easily modified :).