Close
Articles today i learned (til)

How Ink Becomes Art

April 19, 2025

A Brief History of Tattooing

Tattoos have been part of history for thousands of years, serving as cultural markers, expressions of identity, and art. There are many methods of tattooing, such as stick and poke with a mallet and needle and machine tattoo guns. While styles and meanings have changed, one question many people may have is how do tattoos actually work?

The Permanence of Tattoos

The nature of tattoos lies in the body’s response to injury and pigment. In essence, tattoos are an open wound when first done. When a tattoo needle pierces the skin, it inserts pigment into the dermis, the second layer of skin that lies beneath the outer epidermis, which is composed mainly of the cell called keratinocytes. Unlike the epidermis, which renews itself every few weeks, a process called skin turnover, the dermis remains relatively stable, allowing ink to stay in place (Magnum Tattoo Supplies, 2024).

Macrophages, a type of immune cell, rush to the area to absorb the foreign ink particles. Some of these macrophages remain in the dermis with the ink trapped inside, while others die, releasing the pigment again and restarting the cycle. This immune response is important for the tattoo’s visibility and permanence (Mimzi Pma, 2023).

Skin Layers and Needle Depth

Tattooing requires precise depth control. The epidermis, which sheds over time, cannot hold ink permanently. If the needle deposits pigment too shallowly, the ink will fade as the skin regenerates. On the other hand, if the needle penetrates too deeply into the hypodermis (subcutaneous fat layer), it can cause a “blowout”. This is a smudged or blurry effect as ink disperses into fat tissue and can cause scarring (Mykhalevych, 2025).

Daemon, a practicing tattoo artist, explains: “Needle depth is kind of complex depending on the type of skin you’re tattooing and how thick the skin is in certain types of the body… you can tell when you’re going too deep when you see the ink starts to bleed into the vein.” In hand-poked methods, she relies on feeling and auditory cues like a soft “pop” to gauge correct penetration depth.

Pigment Chemistry: What’s in Tattoo Ink?

Tattoo inks are composed of pigments in a carrier solution. Black ink commonly contains carbon or iron oxide. White inks may use titanium dioxide, which can cause allergic reactions in some people. Lastly, colored pigments vary widely. Red often contains mercury sulfide or azo dyes, while greens and blues may include copper-based compounds (Miranda, 2019).

Some inks use organic pigments, especially in vegan or eco-conscious formulations. These pigments can be less stable and may break down faster. Moreover, different skin tones and types can influence how pigments appear and heal. As Daemon notes, “Certain ink might not show up as well on darker skin types… and sometimes ink or healing products can cause mild skin reactions.”

Healing and Aftercare

A fresh tattoo is an open wound, vulnerable to infection and irritation. The aftercare process is crucial to both healing and the tattoo’s long-term appearance. As Daemon emphasizes, “Don’t touch it, don’t scratch it… [because] you’re going to pick the scab off and the ink is going to fall out with it.”

She recommends gentle cleansing with unscented soap, using a thin layer of ointment, and limiting sun exposure. New technologies like second skin bandages offer a breathable barrier during the healing process but must be used with care to avoid excess moisture buildup. Additionally, moisturizing remains important even after healing, as dry skin can cause fading and distortion.

Aftercare is not only about preventing infection but preserving the artwork. “It’s a piece of art,” Daemon says. “Taking care of it and taking care of yourself will make it look super good.”

Concluding Remarks

Tattooing is a combination of biology, chemistry, and craftsmanship. From understanding skin anatomy to mastering pigment behavior and immune responses, both science and skill are important aspects in the art of tattooing. As tattoos continue to grow in popularity and cultural significance, so too does our scientific appreciation for them.

 

Sources Cited

Mykhalevych, Alina. (2025). “Physico-Technical Basis for Needle Depth Control in Fine Line Technique”, Universal Library of Innovative Research and Studies; 2(1): 01-06. DOI: https://doi.org/10.70315/uloap.ulirs.2025.0201001.

Kapoor, Sky. (2021, October 31). From machines to macrophages: Breaking down the science of tattooing. The Varsity. https://thevarsity.ca/2021/10/31/science-of-tattooing/

mimzipma. (2023, July 5). The science of tattooing—Mimzipma. https://mimzipma.com/science/

Miranda, M. D. (2019). Tattoos and tattoo inks: Forensic considerations. WIREs Forensic Science, 2(1), e1360. https://doi.org/10.1002/wfs2.1360

The science behind why and how are tattoos permanent. (2024, February 12). Magnumtattoosupplies. https://www.magnumtattoosupplies.co.uk/blogs/article/the-science-behind-why-and-how-are-tattoos-permanent

Weiß, K. T., Schreiver, I., Siewert, K., Luch, A., Haslböck, B., Berneburg, M., & Bäumler, W. (2021). Tattoos – more than just colored skin? Searching for tattoo allergens. JDDG: Journal der Deutschen Dermatologischen Gesellschaft, 19(5), 657–669. https://doi.org/10.1111/ddg.14436

0Likes
About Author

You May Also Like

today i learned (til)
Should We Be Worried About Zombie Pathogens?
today i learned (til)
That sounds fishy…
today i learned (til)
ADHD, Aging, & Diagnosis
today i learned (til)
Bizzare Medical Treatments: Bayer Heroin

Your journey starts here! Let’s talk!

ThemeRex © 2026. All rights reserved.
  Timothy Durham was convicted of rape when a test showed his DNA genotype matched the DNA recovered from the crime scene. Eye witnesses testified that Durham was in a different state at the time of the incident, but he wasn’t exonerated from his 3000 year sentence until follow up DNA analysis showed that the preliminary forensic analysis used in the trial was misinterpreted (Thomas et al.). DNA testing serves an invaluable part in our criminal justice system, but it comes with complications and bias that can lead to wrongful convictions and misinformed juries.  

Background:

Forensic genetics aims to identify the origin of a biological sample. It can be traced back to Karl Landsteiner who discovered human ABO blood groups. With blood groups, suspects could be eliminated based on their blood type. For example, if a suspect had type A blood and there was type B blood left at the scene by the perpetrator, the investigators could rule out the suspect. Unfortunately, the reverse didn’t work. If the suspect and perpetrator both had the same blood type, it can’t be concluded that the suspect was guilty. Blood identifiers evolved into 8 distinct categories which improved the ability to eliminate suspects, but could only conclude that (if the system matched) it might be the perpetrator or this person might be related to the perpetrator (Jobling and Gill). The field evolved in the 1980s with the discovery of Minisatellites, lines of repetitive DNA that don’t encode proteins. Minisatellite patterns in DNA create what we know today as the DNA fingerprint, and it has a much higher accuracy rate than previous methods (Augustyn et al.). Around the same time, a breakthrough for victims of sexual assault was discovered. In the case of assault, bodily fluids of both the victim and the assaulter can get mixed. A process called differential lysis was created which could selectively increase the concentration of sperm in a fluid sample thereby allowing for accurate DNA testing (Jobling and Gill). Forensics evolved to use single-locus probe testing after several years because of its ease of interpretation. It looked at specific minisatellites that had high variability between subjects. This was the first DNA-based method to be used in a criminal investigation. Two murder homicides from several years apart were connected using DNA evidence. The evidence was then used to exonerate an innocent man, and the guilty party was found when he tried to evade mandatory DNA testing for all men in the small town. His guilt was then reinforced when the DNA profiles matched, and he gave a confession (Jobling and Gill). Finding DNA at a crime scene doesn’t guarantee that you’ll find a murderer. There are issues with non-pure samples and limited samples that make DNA work difficult, and accreditation of facilities and new techniques and take time (Jobling and Gill).  

Subjectivity of DNA Interpretation:

In a 2009 publication, the National Academy of Science discusses the possibility for subjective influence in lab based forensics. The interpretation bias happens in complex cases where, for example, there could be a mixture of DNA. A study published in 2011 looked specifically at this issue. A gang rape happened in Georgia, and the mixture in DNA from the case was used to prosecute one suspect after another suspect took a plea bargain to testify against him. With DNA mixtures, there are three possible conclusions: suspect excluded, suspect cannot be excluded, and inconclusive. If the suspect is excluded, it means that there’s little to no possibility that his DNA is part of the sample. If the suspect cannot be excluded, it means that there’s a possibility that his DNA is part of the sample. In the trial, the DNA examiners who knew the context of the case concluded that the suspect being prosecuted could not be excluded. The 2011 study gave the DNA evidence from this case and the DNA profiles of the suspects to 17 forensic examiners. These examiners had no context of the case, and they all worked independently. Of the 17, only 1 came to the same conclusion (suspect cannot be excluded) as the examiners who knew the context of the case. Twelve of the 17 concluded that the suspect who was prosecuted and convicted had no relation to the DNA found in the sample. Not only does this show that subjectivity occurs due to the context of the case, but the 17 examiners came up with different findings based on their past experiences meaning that not all DNA analysis is objective. Some organizations like the Scientific Working Group on DNA Analysis Methods say that quantitative statistical evidence should be presented with every categorical conclusion, but the US doesn’t require this (Dror and Hampikian).

False Positives:

There are two categories that cause wrongful identification in a DNA report: coincidental matches and false positives. Coincidental matches are DNA matches between two unrelated people. The probability of these matches is about 1 to 500,000 for white individuals and about 1 to 350,000 for black individuals. This small probability of coincidental matches makes people feel confident in DNA evidence. False positives, on the other hand, are matches between DNA and test DNA that result from issues in the forensics lab. There have been multiple cases of forensics labs accidentally switching victim and suspected rapist DNA which lead to convictions that were later overturned when the lab realized the error. There are also cases of misreading or misunderstanding a sample. In a case from 1993, a man was convicted of rape because someone interpreted a mixed sample of victim and perpetrator DNA as an individual sample. The conviction was again overturned. To prevent false convictions, retesting DNA is allowed, but it’s not an efficient solution. Many people are pushing for statistical information on the probability of false positives, so that the jurors can make accurate judgements based on DNA evidence (Thomas et al.).  

Conclusion:

DNA analysis is a useful tool for the criminal justice system, but subjectivity can be an issue in forensic testing. To combat wrongful convictions, there are organizations like The Innocence Project who use DNA testing to free the innocent, but reformed forensic testing standards should be put in place to prevent subjectivity and to ensure juries are correctly informed during trials. https://www.innocenceproject.org/    

Citation:

Augustyn , Adam, et al. “DNA Finerprinting.” Encyclopedia Britannica , 26 Apr. 2018, www.britannica.com/science/DNA-fingerprinting#ref153186. Dror, Itiel E., and Greg Hampikian. “Subjectivity and Bias in Forensic DNA Mixture Interpretation.” Science & Justice, vol. 51, no. 4, 2011, pp. 204–208., doi:10.1016/j.scijus.2011.08.004. Jobling, Mark A., and Peter Gill. “Encoded Evidence: DNA in Forensic Analysis.” Nature Reviews: Genetics, vol. 5, no. 10, Oct. 2004, pp. 739–751., doi:10.1038/nrg1455. Thompson, William C, et al. “How the Probability of a False Positive Affects the Value of DNA Evidence.” Journal of Forensic Sciences, vol. 48, no. 1, Jan. 2003, pp. 1–8., doi:10.1520/jfs2001171.