Stencil Science- Surfactants

Stencil Science- Surfactants

August 25, 2016 3 Comments


Its been a little while since we ran a “Stencil Science” feature, mostly because we’ve been on the road or preparing for the next S8 Tattoo Roadshow. But we’re back this week with a quick primer on a group of compounds that S8 relies on to do a lot of heavy lifting in our products- surfactants.

 We’ve mentioned surfactants before in conversations about cleaning and preparing the skin. And vegetable based surfactants largely explain how S8 makes sls-free, alcohol-free cleaning and preparation products. But before we get into this, we should define our terms.

The word “surfactant” is a portmanteau: it combines the words “surface,” “active,” and “agent.” This creative respelling clearly describes what surfactants are- they are compounds or agents that act on the surface of other things. More specifically, surfactants lower the surface tension or interfacial tension of liquids.

Surface tension is one of those hugely important concepts for tattooers that we feel has gone under-explained. While we’re not going to get into the manifold places surface tension plays a role in tattoo artists’ day-to-day lives, we do want to briefly talk about how S8 uses surfactants to make artists lives easier. And to do that, it’s probably a good idea to point to the one area every tattooer has experience with surfactants- dish detergent.

Let us imagine we are cooking a chicken (apologies to vegetarian and vegan readers, but animal fats help explain this process. We promise we’ve got a vegan friendly experiment you can try on your own time). As the chicken roasts a tremendous chemistry experiment is unfolding. Fats phase-shift from solid to liquid, waters evaporate, and proteins break apart or unspool. If you seasoned the chicken, the phytochemicals of the herbs change flavors, textures, and might even impact how long the leftovers keep. Entire college courses have been written on this complicated scientific process. But the chicken is ultimately of no concern to us in this little analogy. What really matters is what is going on in the pan, both as you cook and while you eat.

The pan is metal- probably aluminum or maybe stainless steel (fancy pants). While you cook the bird, "stuff" drips down and accumulates in the pan. Ideally you make your own gravy from this fluid- if you don’t, it congeals while you eat. Either way, you’ll likely have “something” left over in the pan- this "something" is composed of oils, water, proteins, and vegetable-based components (e.g. cellulose) that result from the cooking process. And you have to clean it up.

You might initially rinse the pan with water to remove large pieces of skin, vegetable, even semi-solid fats that may have cooled and hardened. But a rinse won’t cut it- the water that you’re using to rinse out the pan has a hard time removing surface fats that coat the top of the pan. An oily film probably covers large sections of the pan, and "baked on" residue probably complicate the matter. That means its time to pull out the dish detergent.

Dish detergents are amphiphilic surfactants- they are at once hydrophobic and hydrophilic. This means that they can be used to get oil and water to “mix” (more specifically, they emulsify and suspend fats inside water, forming what amounts to a colloid). They do this by changing the interfacial tension of the oil and water. As anyone who has attempted to make their own salad dressing or has purchased an Italian dressing from the store knows, oil and water tend to separate out. Oil and water are extremely “cohesive”- they are attracted to themselves, resulting in fairly high surface tensions. In practice, this means that it requires a large amount of energy (for example, shaking the jar) to mix oil and water, and because oil is immiscible in water, it will always separate out.

The surfactant in dish detergent changes the equation. By modifying the surface tension of the oil, the surfactant makes it easy to mechanically break apart oil droplets. In fact, the surfactant stabilizes these very small clusters of oil, allowing them to be washed of the surface of the pan and down the drain. So, while the surfactant doesn’t make oil miscible in water, it allows oils to be suspended in water in very small droplet sizes, making clean-up easy.

So what does any of this have to do with tattooing? Remember our long talk about skin prep weeks ago? Human skin oils (which we are absolutely covered under) have the same cohesive surface properties that chicken fats do- that is to say that they don’t mix well with water. And most commonly used topical cleaners like green soap don’t really have a surfactant. Without a surfactant, green soap doesn’t substantively do anything to remove the human skin oils that impact both stencil application and post tattoo healing.

S8 RED Soap is different. We use a high power, botanical-based surfactant that decreases skin oil surface tension and increases miscibility. This means that properly cleaning the skin prior to a tattoo is easy and requires significantly less energy- i.e. less rubbing. It also helps that S8 RED Soap reduces redness before and during that tattoo process, improving color fidelity.

The same surfactant we used in RED Soap also pulls its weight in RED Needle Cleaner. Most tattoo inks feature propylene glycol and/or glycerol, which are often used as components in the carrier as a means of suspension and to modify flow rates of the ink. While both propylene glycol and glycerol are both water miscible, adding an amphiphilic surfactant like RED Needle Cleaner to a rinse cup can dramatically reduce rinse and color change times. And RED Needle Cleaner also removes nut-based fats that might clog needles and tubes- these ingredients are commonly found in tattooing glide and aftercare products, but of course not in S8 Tattooing Gel (which was formulated not to accumulate in needles).

So we promised a science experiment/test for our vegan, vegetarian, and hell for our omnivorous readers as well. You’ll need a two tablespoons of peanut oil (which is chemically very similar to the oils found on human skin), a half of a cup of water, and a packet of our RED Soap- shoot us a message and we’ll send you a sample, free of charge. Pour the water, peanut oil, and RED Soap into a jar, shake it, and leave it out on a counter. Run a control test, repeating the steps but omitting the RED Soap. When you compare them minutes, hours, even days later, you’ll notice that the jar containing RED Soap has not separated to the same extent or at all when compared to the jar without it.

What does this tell us? Well, it shows that the surfactant in RED Soap is very effective at changing the surface tension of the fluids in the jar. Because these fluids approximate the conditions on the surface of the skin prior to cleaning, we can see the method of action of RED Soap. It breaks apart large drops of peanut oil and suspends them, allowing them to be rinsed away with water. And trying to clean out the jar that did not have the RED Soap is going to prove much harder than the one that did include it, thanks to the fact that the emulsified oils do not come into as much direct contact with the glass surfaces of the jar- i.e. less or no oily film. Surfaction in action… Ugh.

A couple of closing comments- First, do us a favor and don’t drink the RED Soap or Needle Cleaner. While all the ingredients are totally safe, and while the water, RED Soap, and peanut oil test is one step away from being a recipe for a passable, non-separating salad dressing, we make tattoo products not cooking ingredients. So, just like you wouldn’t shotgun a 1 ounce of Eternal Ink Purple Concentrate, don’t put S8 products in your mouth.

Second, if you are in the Sacramento or Portland area, join us for the S8 Tattoo Roadshow. RSVP to reserve your spot- attendance is free. Links for PDX and SAC are here.

And third, as always, leave us questions, comments, and feedback here or on our facebook page. Be sure to follow us on Instagram.

3 Responses


May 03, 2022



April 18, 2022

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March 18, 2022

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