Dear Readers,

Today’s blog post is focused around the trendy activity of ‘Slime’. Speaking from experience, kids go crazy for slime - its squishy and malleable texture increases their imagination and allows them to come up with new and different ways of playing with it through each use. Forget play dough and clay, slime has quickly become extremely popular not only amongst the youngest, but also amongst popular adults and teenage influencers. 

‘How to Make Slime’ and ‘Playing with Slime’ YouTube videos are fast growing in views and popularity, with the audience mostly built up of children under 15, I was fascinated with how quickly this activity and industry was growing. After some research, I finally understood why this mere game has acquired such an audience. 

In this post we are going to do an extended explanation of all the frequent questions about slime, from the most common components and recipes to the benefits and safety considerations. 

DEFINITION

Slime-toy is a unique semi-viscous material ideal to play. Scientifically is classified as a non-Newtonian fluid, which means thick liquid that have a variable viscosity.

This cool toy is creating by combining polyvinyl alcohol solutions with borate ions forming a cross-linked polymer that has the semi-viscous characteristics that makes it unique and interesting to children.

Its semi-viscous consistency makes it malleable and stretchy in a particular way that provokes anyone who plays it transform it into different fickle shapes. Slime can be combined with colors and other decorative materials (toppings) that increases it interest to play in many ways.  

Slime can be considered a learning toy because helps to develop sensorial skills by playing the informed and malleable material and by adding several toppings that makes it even more interesting. It is also a scientific toy, as there is a chemistry involved to create this semi-viscous material.

COMPONENTS

To make classic Slime, only two ingredients are necessary to create the reaction that will produce a squishy Slime. These 2 ingredients are PVA glue, and Borax. However, other ingredients such as Sodium bicarbonate are alternatives that can also optimize the consistency of slime. We categorize these ingredients as: GLUE and ACTIVATORS

As explained below, on the Safety Section, it is not recommended to use high concentrations of borax as it can cause skin irritation, therefore, we suggest to use an alternative product instead that includes borax but in a very low concentration; contact lens solutions, or saline solutions are two perfect alternatives. To make slime, be sure that the lens solutions or saline solutions that you buy contain boric acid and sodium borate, which necessary to produce the slime texture by mixing it with the PVA glue.

1. GLUE

• PVA White glue. Common school white glue, easy to find in any stationary shop
• PVA Clear Glue. Common school clear glue, easy to find in any stationary shop

2. ACTIVATORS

• ACTIVATOR A: Sodium Bicarbonate- Baking soda is used to facilitate the reaction of the slime, giving it a firmer consistency, especially when using contact lens solution as Activator B.

You need to add Activator A in first place, then add the Activator B

• ACTIVATOR B: Borax and Products containing borax.

-Borax– It is a basic ingredient to make slime, however this is the ingredient that most people are concerned about (see below), therefore we recommend not to use borax in the Slime and use other substitutes containing boric acid and sodium borate.

-Liquid starch – Products like sta-flo used are liquid starch, used commonly to provide stiffness to fabric in your clothes after washing, but as they contain sodium borate, they are a good activator to make slime

-Contact lens solution or saline solution – These are nontoxic, but there may be sodium borate in some of these solutions. Take the same precautions as with using borax. (see below)

By mixing glue and activators, children would be able to play around with the quantities of these ingredients, to create slimes with different viscosities. For example, the more contact lens solution you add the thicker the slime becomes and vice versa, the less you add the oozier it becomes.

Alternatively, there are other less common compounds that can be added to a slime formula, usually to explore and modify different consistencies to the classic slime.

3. OTHER COMPOUNDS

• TO CHANGE CONSISTENCY:

Shaving cream – Absorbs the moisture and changes the consistency to the Slime making it fluffier with a similar consistency to marshmallows.

Clay – It is used to change the consistency of the classic slime, by adding clay the slime becomes firmer and more malleable (kind of like play dough).

Fake snow – It is used tochange the consistency of the slime, becoming less sticky and fluffier.

• ADD-ON’S:

Colors, scents – Adding a color or a scent makes this toy more fun, and more visually aesthetic.

• TOPPINGS:

Glitter, beads, polystyrene balls, etc – Decorating the slime with glitter, beads or any other sprinkles is a way to make slime more fun, more sensory, and more visually interesting. 

TYPES

There are many types of slime recipes available online and on YouTube, each with different twists in the consistency and appearance of the classic slime. In this section of the blog post, I mention the most popular ones.

A slime that has become particularly popular lately is the edible Slime, which has attracted the attention of many adults due to the exclusion of borax or any products containing borax. This slime is called Oobleck Slime. It has similar properties to the classic slime and uses edible ingredients, making it a preferred option for many parents due to its safety in case of any accidental ingestion of the product, a slime that is more suitable for any child under the age of 5. 

WHITE GLUE BASED SLIME

White glue + Activator (Sta-flo, contact lens solution, borax, baking soda) + Add-on’s (color, scents) + toppings

RECIPE

1. Poor White glue into the bowl
2. Little by little, add your activator 
3. Add your Add-on’s and toppings (optional)

CLEAR WATER SLIME

Clear glue + Activator (Sta-flo, contact lens solution, borax, baking soda) + Add-on’s (color, scents) + toppings

RECIPE

1. Poor Clear glue into the bowl
2. Little by little, add your activator 
3. Add your Add-on’s and toppings (optional)

FLUFFY SLIME

White glue based slime + shaving foam or/and foaming soap

RECIPE

1. Make White glue based slime
2. Add shaving foam or/and foaming soap

CLOUD SLIME

White glue based slime + Fake snow + Activator + Add-on’s + toppings

RECIPE

1. Reconstitute the Fake snow by adding the fake snow powder to a bowl of warm water
2. Make White glue based slime
3. Place your white glue based slime into the fake snow and kneed
4. Add more activator

BUTTER SLIME

White glue or clear based slime + Clay + Add-on’s + toppings

RECIPE

1. Mix clear or white slime with clay
2. Add your favorite color and accessories

EDIBLE SLIME or OOBLECK SLIME

This slime is a totally different slime, there is not glue involved, and the reaction is not a cross-linking reaction like the one occurring by mixing PVA Glue and Borax. 

In this slime you only need Corn Starch and Water, creating a reaction called Oobleck. The product of this reaction is a non-Newtonian fluid similar to that of the Classic Slime, but in this case the slime is less sticky. Slimes made out of corn starch have a matte finish and are more solid rather than liquid. 

Using corn starch, water and food additives make this product edible.

Corn Starch + Water + Add-on’s + toppings

RECIPE

1. Mix Corn Starch and Water
2. Add your favorite color and accessories

THE CHEMISTRY OF SLIME

Classic slime is created by combining 2 ingredients: PVA glue and Borax. These two compounds react creating a three dimensional network that traps water, in a process called a cross-linking reaction. The product of this reaction is a highly flexible, non-Newtonian fluid; AKA the semi-solid gel that we well know as Slime.

REAGENTS:

PVA GLUE. Polyvinyl alcohol is a water-soluble synthetic polymer. It has the chemical formula of: (C2H4O)x

 

BORAX. also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid.  Its chemical formula is: Na2B4O7. 10H2O (also written as Na2[B4O5(OH)4]·8H2O)

CROSS-LINKING REACTION:

This is the chemical process for the cross-linking reaction in the Slime:

The two reagents PVA and Borax are combined to make classic slime. (C2H4O)x + (Na2B4O7.10H2O) 

Borax in water releases sodium ions, Na+, and tetraborate ions.

The tetraborate ions react with water to produce the OH- ion and boric acid:
B4O72-(aq) + 7 H2O <—> 4 H3BO3(aq) + 2 OH-(aq)

Boric acid reacts with water to form borate ions:
H3BO3(aq) + 2 H2O <— > B(OH)4-(aq) + H3O+(aq)

Hydrogen bonds form between the borate ion and the OH groups of the polyvinyl alcohol molecules from the glue, linking them together to form a new polymer: slime.

The cross-linked polyvinyl alcohol traps a lot of water, which is why slime is wet. You can adjust the consistency of slime by controlling the ratio of glue to borax. You can also adjust the recipe by limiting the amount of water that you use. 

In this reaction, if you add acids such as Vinegar (acetic acid) to slime, it would destroy the cross-linking reaction, and cause it to become liquid, whereas the bases of Baking soda (Sodium bicarbonate), neutralizes the acid allowing the cross-linking to reform.

After learning how slime works and the science behind its composition, we have developed the perfect combination of reagents to get for the best consistency for Slime.

In our perfect formula for DIY Slime, we added a third reagent which is the Baking Soda (Sodium bicarbonate). As explained before, the Sodium bicarbonate is a base that creates stronger cross-links between the PVA and Borax. Using Sodium bicarbonate helps the slime have more form and firmness.

In our DIY slime formula, we mix the PVA (GLUE) with the Baking soda (ACTIVATOR A), and then we add the contact lens solution (ACTIVATIOR B). By mixing the correct amount of each reagent the cross-linking is created between the borate ions and the OH groups of the PVA glue, obtaining the perfect elastic consistency in the slime.

No more need for experimenting, we have created the perfect slime formula, here is our secret!

 

PERFECT SLIME FORMULA:

-1 cup (230 ml) of PVA glue

-1 tsp of bicarbonate of soda (baking soda)

-1 tbsp of contact lens solution containing boric acid and sodium borate

-Add-on’s and toppings

BENEFITS

Playing with and making slime comes with many benefits. In this section of the blog post I will be explaining why children have expressed such an interest in this toy and what benefits they can gain from it. To summarize, below is a list of bullet points that highlight the benefits of slime making:

1. Imagination
2. Sensory stimulation
3. Stress relief
4. Entertainment
5. Concentration
6. Science!

Drawing back to a point I brought up earlier, slime increases and stimulates children’s imagination. Not only can they come up with different and innovative ways of using it, but they can also create and customize different designs or colors for their slime, they can create their own variations changing ingredients, or mixing the formula with beads, glitter, etc. This will also help them decide what colors and textures they find most appealing, broadening their knowledge and opening their minds to the different senses and their own preferences. 

This brings me to the next benefit: Sensory Stimulation. Playing with slime is a sensory play activity which allows children to utilize and understand all five senses. When several senses are stimulated at once, children build their creativity and learning through exploration. This also helps to provide them with psychomotricity and calmness. Slime is also a very durable form of entertainment which adds to the long list of reasons that support its rapid popularity. 

Some kids like to keep their hands busy and this also helps them focus. In learning how to make slime and playing with it, they apply focus and a certain level of concentration into the process, this can then be adapted to other aspects of their daily lives. Furthermore, much like any other squishy toy for adults, slime acts as a stress relieving tool, it offers a productive and healthy alternative brain break from school work! It has become so popular around school even the kids have started to concoct their own “secret formulas” and become little entrepreneurs by selling friends their slime! It has become a long lasting passion for many, many kids. 

Our final, and favorite benefit to Slime is SCIENCE! Slime involves chemistry! Chemistry is all about states of matter including liquids, solids, and gases. It is all about the way different materials are put together. Additionally, Chemistry shows us how each material will react under different conditions. In a different section we talk about the chemical involve in the reaction of making slime.

Another interesting, scientific fact is that Slime is a non-Newtonian fluid. A non-Newtonian fluid is neither a liquid or a solid. It can be picked up like a solid, but it will take the shape of its container, like a liquid! Slime does not have its own shape. Kids can learn about many chemical properties and reactions in the simple, and safe process of making slime!

Albeit the benefits of slime, there have been a few slime toxicity concerns amongst parents roaming around the internet. In this section of the blog post, I will now be demystifying the possible hazards involved in making slime, and playing with slime. This section of the Blog is entirely based on scientific research, with references listed below in case any of you are interested in learning more. 

SAFETY

There had been some concerns around Slime that have arisen worries in parents. Most of the concerns are related to the potential toxicity of one the ingredients in Slime: Borax.

Below is information related to slime taken from the pharmacist and clinical toxicologist; Sheila Goertemoeller, who has had 22 years of experience in poisoning management at the Drug and Poison Information Center Hotline at Cincinnati Children’s, debunking any slime myth and worry revealing the potential toxicity of borax to warn the parent how to intervene choosing the correct ingredients and supervising responsibly when their children play slime.

BORAX/ SODIUM BORATE

This section is purely dedicated to Borax/ Sodium Borate. Since the few toxicity concerns that have surfaced involving slime are related to this component, here we will be revealing the reasons as to why it causes fret and what you can do to prevent any possible dangerous outcomes. 

Borax is a component used in many detergents, cosmetics, and enamel glazes. Now it is also commonly used as an activator in making slime. Its purpose is to create the oddly appealing viscous, sticky consistency in slime.

Although borax, or Sodium tetra borate, is not acutely toxic, it is extremely alkaline, which would cause irritation if used undiluted. 

Borax acts as a “slime activator,” and is most commonly used in the form of Borax powder mixed with warm water which is incorporated to the slime mixture. Alternatively, you can use other slime activators that contain smaller amounts of borax such as: liquid starch or contact lens solution. 

The reports on slime toxicity have all been caused due to excessive amounts of borax used as activator. High levels of Borax in slime has caused irritation of the skin, and its ingestion has also provoked diarrhoea, vomiting and cramps. Any handling of Borax must be done so carefully, and its ingestion is TOXIC and UNSAFE, it should be used in small amounts and under adult supervision. 

On the other hand, it should be stated that the US authority says Borax/ Sodium borate is ‘generally safe’. Dr. Kyran Quinlan, chairman of the American Academy of Pediatrics' Council of Injury, Violence and Poison Prevention, has previously assured that “Borax is a mild irritant,” he says. "I love that kids are having fun with slime, and it is generally safe.”

Moreover, Dr. Goertemoeller (mentioned previously) says that making homemade slime is a safe, fun activity, as long as it is done with adult supervision. The biggest concern is if any of the ingredients in non-edible slimes are eaten or swallowed. So keep an eye on young children and pets while slime-making is going on. 

For any alternatives, there are also many slime recipes that are actually edible! Have a good look online for some ideas (I saw some birthday cake slime somewhere!, he says)

WHAT ARE THE RECOMMENDED LEVELS OF BORAX

According to the Children's Hospital of Wisconsin, as little as 5 grams of borax can be harmful and potentially fatal to a child if ingested. However commercial slimes are have to contain

It is recommended that Borax is diluted in warm water or is used in alternative ingredients that contain borax in smaller amounts (liquid starch or contact lens solution).

Adult supervision is essential when playing and making slime to prevent any accidental ‘ingestion’, and in making sure that they wash their hands after ANY and EVERY activity, to avoid any possible harm.

OTHER CONCERNS RELATED WITH GERMS

These days we are all affected by Covid 19, and now there is an even bigger safety concern about germs, bacteria or any other problem related to toys that could detriment children. 

According to the declaration of Josh Schaffzin, MD, PhD (assistant professor in Division of Infectious Diseases of at Cincinnati), a virus is the most common contagious germ that exist… and it CANNOT grow on slime. However they can get there from someone’s hands or a sneeze, and they’ll stay alive for a few hours.

Other germs like bacteria or molds, need food and a comfortable environment, typically a warm, dark place. The ingredients in most homemade slime recipes — white glue and borax — don’t provide that kind of environment. So it’s unlikely that any bacteria or mold would grow on your slime at all, and if so, it would grow very slowly.

Therefore,  slime is not necessarily a “blob of germs”. 

However, we recommend you put it away when you are finished playing with it, sealed in a plastic bag or container, which will further ensure a safer experience when playing with it, as well as making its squishy consistency more longterm. Storing it in the fridge might slow bacteria and mold growth further 

These days we are all affected by Covid 19, and now there is an even bigger safety concern about germs, bacteria or any other problem related to toys that could detriment children. 

SO… IS SLIME TOXIC?

According to a number of doctors, pharmacists and scientists SLIME IS NOT TOXIC.

Slime and DIY slime is mainly a fun activity that has a number of benefits and guarantees hours of entertainment. But as any other toy, it should be made, and played with under adult supervision, especially when being used by younger children.

The recommended age to start playing with slime is > 5years old.

For DIY slime, we recommend not to use pure borax and using contact lens solution or saline solutions containing boric acid and sodium borate instead.

Furthermore, slime is not a source of contamination, as mentioned before viruses cannot grow on slime. However, to prevent other germs like bacteria or molds sticking to or growing on the slime, we recommend that you make sure the children wash their hands before and after playing slime (AND WITH ANY OTHER TOY/ ACTIVITY), and seal it in a bag or container and store in the fridge for a better conservation and durability of the toy.

HOW TO INFORM YOURSELF ABOUT SAFETY PROPERLY

-Slime and DIY Slime should be labeled properly, indicating the formula and relevant information about ingredients

-It would need to indicate the suitable age to play with this product (for slime usually >5years old)

-Indicate to play under adult supervision

-Recommend to make sure kids wash their hands before playing to avoid germs to stick to and/ or grow on the slime, and after, to avoid any possible skin irritation

STATEMENT

After all this research, it has become clear that making homemade slime or playing with slime is a safe, and fun activity that amuses the children and helps them explore in different ways, making this toy very popular amongst children (or adults!). Therefore, overall we consider it not only a safe and fun activity but also a game that we would highly recommend! Of course, as long as it is done under adult supervision, and HANDS ARE WASHED!

 

Best wishes,

 

Lucrecia Rodríguez de Acuña

Creative Director

Fiesta4U.com