What is silica gel and what are its benefits?
A little while ago, we published an article about silica gel. It turns out that it is a product that indicates silica gel. But just as people often assume that all silica gel products are for cleaning, people also assume it is a desiccant. It is not: it’s a product that indicates silica gel.
More specifically, it is a product that turns blue when 30-40% of its volume has been absorbed with moisture (usually in the form of water), and turns pink when more than 40% has been absorbed (not to be confused with the color of the glue or adhesive itself). This can be an extremely useful product for drying materials like food or drink containers, or for helping to dry objects without heat or electricity.
A little bit about silica gel:
Silica gel was discovered in 1883 by two chemists who were looking for ways to prevent salt from crystallizing during concentration processes by reducing its density. They used sodium hexametaphosphate and sodium hydroxide to obtain this end result but were quickly induced to abandon their research because of the difficulty of controlling reaction conditions under which they were working (the reaction was exothermic).
Silica had been isolated earlier but it was not until 1883 that they found a way to synthesize it synthetically. In 1891, Dmitri Mendeleyev classified the chemical structure of silica into three phases: silicon dioxide (SiO2), oxygen dioxide (O2) and oxide (having multiple crystalline lattices).
SiO2 – Silicon dioxide; SiO2 – Silicon oxide; O2 – Oxides; SiO3 – Silicon oxalate; MoO3 – Monoclinic oxide; and so on. Silicate mineral is composed mainly of silicon dioxide and oxygen dioxide with very small amounts (less than 1%) of magnesium oxide and titanium dioxide.
In other words, silicate is a kind of carbonate mineral with high degrees of purity (>95%) as it contains no carbon atoms and hence no bonds between them. Silicates are very important in construction materials such as cement, gypsum plaster material, concrete aggregate etc., because they can be used as binders without any ill effects on strength, durability or porosity properties when compared to other binders such as Portland cement.
This phenomenon was called “silicate dispersion” because air bubbles dissolved in water were dispersed when treated with high concentrations of silicates.
How does silica gel work?
The above is a great example of an excellent summary, written for a scientific audience. But in the world of marketing, one doesn’t always have to use regurgitated facts (or even make a scientific argument) to impress your target audience.
The reason for writing this post is because I recently had the opportunity to see the latest version of Silica Gel Indicator Beads during its booth at the recent Drone Expo in Las Vegas. The product was developed by Aeroflite and it uses its patented technology to turn blue when 80% or more silica gel has been absorbed with moisture. It makes an excellent product – and that’s cool — but it is also useful as a means to draw more attention towards your product (as well as demonstrating that you are serious about your business).
I have quite a few interesting things I would like you to read on this topic, so please feel free to click the link one of these below:
- Silica Gel Indicator Beads: Turning Blue When 80% or More Silica Gel Is Absorbed With Moisture
What are the dangers of using silica gel?
This is a very good question. In the past, many desiccants were colored with metallic pigments. This was to make their physical properties more noticeable in the field and also to make them easier for people to visually identify. But this is not the case anymore, and there are now no visible coloration of the desiccant itself.
The reason for this is that many of them have a pH of 8 or above. As soon as you start adding water, the desiccant can no longer hold its shape (and hence begin breaking down) even if it’s still green or yellow at room temperature, so most colored desiccants can only be used in very dry environments like mineral-rich deserts or polar regions.
A lot of companies have begun using uncolored silica gel (UASG), which has a lower pH and has traditionally been used in very dry environments where coloration is not a concern (for example, in hydroponic systems without much water). However, UASG has been shown not to have any visible coloration even when it’s still green-ish at room temperature (a phenomenon known as “sublimation”).
This suggests that we must be more cautious before using UASG in our products to avoid being stuck with an unusable product that’s only usable up until you add water.
The point here is that now we know that most colored silica gel beads will turn blue when you put them into moist conditions, but this doesn’t necessarily mean they are safe to use on our products or that they are less dangerous than uncolored ones. To me it seems like something should be done here as well: we should make sure there aren’t any colored silica gel beads in our products so other companies don’t end up “up-selling” us based on misleading information about their product quality (which would probably make some users angry enough to switch).
How can you tell when silica gel is full?
There are a lot of products on the market today that indicate the level of silica gel when connected to the product in some way. This is typically done via color or by weight.
What’s important to note here is that these indicators are not as accurate as you might think and there are many other factors to consider, including:
- The level of moisture in the air, which depends on temperature
- The amount of moisture already in the product – for example, if it is pre-moistened with a soap or deodorant
- How long the product has been in storage (some indicators start to give out after a few weeks of being stored)
What should you do with a full bag of silica gel?
A bag of silica gel will tell you how much is left to absorb moisture, when it will turn blue or pink. The color on the bag, as you can see, is a mixture of blue and pink. This color is caused by a chemical reaction when the silica gel absorbs water and sets into a solid state.
The color is proportional to the amount of silica gel that’s absorbed with water and sets into a solid state. In other words, the color changes from blue to pink as you add more water — but the change in color is not linear. Instead, it changes in both directions at different rates (the higher the amount of water added, the faster the change in color).
This concept is called hydrodynamic saturation (the idea being that if you saturate one spot with more water than another spot), there should be some intermixing of colors: some areas will absorb more than others because they are saturated with more water than others; whereas other areas will absorb less because they are saturated with less water than others.
In practice, this means that if you want to know how much extra moisture your product will absorb before turning blue or pink (or before it turns brown), you need to test in an area that has little or no moisture already — otherwise you won’t know exactly how much extra moisture your product will absorb before turning blue or pink.
Where can you buy silica gel?
We have not seen this in the market yet, but the US has strict regulations on labeling silica gel as desiccant. The labels for desiccants, like a lot of other things, are very confusing. As such, it is important that you understand some basic terminology when it comes to silica gel, which is used in dry foods and beverages as a desiccant.
The general idea is that you need to package foods or beverages in order to keep them from drying out when you open them up and consume them. And that is true no matter what kind of food or beverage you use: fruits and vegetables, meat and poultry, breads and pastries — there are a number of different kinds of foods (and beverages) on the market today. But whether or not you package your food or beverage depends not just on how tightly you seal the container (we will get to that in future posts), but also on what kind of desiccant you put inside the package. The most common desiccant used by food manufacturers is silica gel (silica sand), which has very specific properties — see our post on how to use silica gel with pasta here).
The best way I’ve found so far for people who cannot find enough information about this topic online is by doing some research at your local grocery store. You can find cereal boxes with the word “desiccant” written prominently at the top alongside other products like rice or flour. If there’s no “desiccant” label at all then try looking for “silica gel” instead — just make sure not to confuse either word with other similar ones like starch or sugar.
How long will silica gel last?
There are a few things to consider when deciding whether or not to use a desiccant. One of them is the nature of the product. A desiccant is a substance that adsorbs water molecules, and by tensioning the air, it can be forced to absorb moisture.
If you are using pure silica gel, which adsorbs water before it oxidizes, then it will last longer than most other desiccants. But if you are using impure silica gel that adsorbs water instead of forming a solid film as it usually does, then in order to remain effective you may have to remove or dilute with something like water before use.