What makes tattoos permanent is a TEd lesson by Claudia Aguirre in which she tries to give a scientific answer to the question 'how do these markings last?'. She also details the different methods, machines and macrophages that go into making tattoos stand the test of time.
Self-study activity:
There's quite a lot of scientific name-dropping in this video, which might make it a bit difficult for learners to understand. Don't be deterred by the jargon and just focus on the task at hand, which is quite general.
Watch the video and say whether the statements below are true or false.
You may also want to go to the original TEd-ed lesson and do the activities suggested there. Remember that you will find more comprehension questions in the Think tag, suggestions to explore the topic further in the Dip deeper tag and some topics for discussion in the Discuss tag.
1 No tattoos have been found in human remains before Christ.
2 Human skin falls off like that of snakes.
3 Thomas Edison invented the electric tattooing machine.
4 The tattooing process is similar to causing a wound to the body.
5 Sun exposure and swimming help tattoos to fix.
6 With time tattoos become paler.
7 In most cases, tattoos stay fixed in a person's skin for life.
8 With the help of a laser, tattoos can easily be erased.
Tattoos have often been presented in popular media as either marks of the dangerous and deviant or trendy youth fads, but while tattoo styles come and go and their meaning has differed greatly across cultures. The practice is as old as civilization itself. Decorative skin markings have been discovered in human remains, all over the world with the oldest found on a Peruvian mummy dating back to 6000 BCE.
But have you ever wondered how tattooing really works? You may know that we shed our skin, losing about 30,000 to 40,000 skin cells per hour, that’s about a million per day. So, how come the tattoo doesn’t gradually flake off along with them. The simple answer is that tattooing involves getting pigment deeper into the skin than the outermost layer, that gets shed. Throughout history different cultures have used various methods to accomplish this, but the first modern tattooing machine was modeled after Thomas Edison’s engraving machine and ran on electricity.
Tattooing machines used today insert tiny needles loaded with dye into the skin at a frequency of 50 to 3,000 times per minute. The needles punch through the epidermis, allowing ink to seep deep into the dermis, which is composed of collagen fibers, nerves, glands, blood vessels, and more. Every time a needle penetrates it causes a wound that alerts the body to begin the inflammatory process, calling immune system cells to the wound site to begin repairing the skin and it is this very process that makes tattoos permanent.
First, specialized cells called macrophages eat the invading material in an attempt to clean up the inflammatory mess as these cells travel through the lymphatic system, some of them are carried back with a belly full of dye into the lymph nodes, while others remain in the dermis, with no way to dispose of the pigment the dyes inside them remain visible through the skin. Some of the ink particles are also suspended in the gel like matrix of the dermis, while others are engulfed by dermal cells, called fibroblasts.
Initially ink is deposited into the epidermis as well, but as the skin heals the damaged epidermal cells are shed and replaced by new dye free cells with the top most layer peeling off like a healing sunburn. Blistering or crusting is not typically seen with professional tattoos and complete epidermal regeneration requires two to four weeks during which excess sun exposure and swimming should be avoided to prevent fading.
Dermal cells, however, remain in place until they die. When they do they are taken up ink and all by younger cells nearby so the ink stays where it is. But with time tattoos do fade naturally as the body reacts to the alien pigment particles, slowly breaking them down to be carried off by the immune system’s macrophages.
Ultra-violet radiation can also contribute to this pigment break-down, though it can be mitigated by the use of sun block. But since the dermal cells are relatively stable much of the ink will remain deep in the skin for a person’s whole life, but if tattoos are embedded in your skin for life is there any way to erase them. Technically, yes.
Today a laser is used to penetrate the epidermis and blast apart underlying pigment colors of various wavelengths. Black being the easiest to target, the laser beam breaks the ink globules into smaller particles that can then cleared away by the macrophages, but some color inks are harder to remove than others, and there could be complications; for this reason removing a tattoo is still more difficult than getting one, but not impossible.
So, a single tattoo may not truly last forever, but tattoos have been around longer than any existing culture, and their continuing popularity means that the art of tattooing is here to stay.
Key:
1F 2T 3F 4T 5F 6T 7T 8F
