Glass is so commonplace in the modern world that it is often taken for granted. For those of us who enjoy working with glass though, it becomes an obsession.
The most dedicated and motivated among us sometimes consider bringing their hobby to the next level by making their glass themselves from locally sourced river sand, but is that really a good idea?
Can you use river sand to make glass? River sand can be heated to the point that it becomes glass, but unprocessed, natural river sand may not have ideal percentages of silica and often contains impurities that will negatively affect the finished glass in terms of color, clarity, and workability.
The sand in and around river beds is abundant, and depending on the type and purity of the sand, it may be just what you were looking for if you were considering melting sand down into glass yourself.
Unfortunately, not all river sand will produce desirable results. Let’s take a closer look at whether or not using river sand to make glass is actually a good idea.
Most people know that sand is involved when making glass, but many are unaware of the actual process and incredible heat involved.
If you’re considering making your own glass from river sand, it’s important to have a good grasp of the fundamentals first, or you will be setting yourself up for failure before you even begin.
So, how is glass made?
On its own, sand will begin to melt shortly after reaching temperatures slightly over 3,000℉.
That is quite a bit of heat, and many kilns aren’t quite up to the task.
However, flux additives such as potash, sodium carbonate, or sodium oxide will reduce the melting point significantly.
A downside of using a flux additive is that it makes the glass water permeable and eventually water soluble – not exactly ideal for glass.
A stabilizer such as lime must be added to counteract the negative effects of the flux and add solid properties and durability to the glass.
Generally, the final mixture would consist of about 60% sand and 40% additives.
The mixture is placed into a heat-proof crucible, and into the furnace or kiln it goes until it becomes liquid glass.
The time needed for this to happen depends on the temperature of the furnace, the amount of mix being melted, and the exact ratio of sand to additives.
Once the sand has become molten glass, it may be gathered on the end of a metal tube and blown (you can read more about glass blowing here) or shaped and molded according to the artist’s vision.
Will River Sand Work?
Well, maybe, but maybe not. The answer here really depends on several factors.
Broadly speaking, some river sand can be successfully used to make molten glass, but the quality will likely be pretty poor due to the presence of impurities.
Unless you already have the ideal setup in place and really know what you are doing, the odds are rather high that you’ll be disappointed with the results.
However, it can be done in certain circumstances.
Let’s take a look at each of the factors that determine whether or not river sand should be used.
Not every source of sand is ideal for glass making.
Some river sand has enough silica content (greater than 95% silica) to be considered true silica sand (also known as quartz sand).
For example, sand along portions of the Mississippi River contains high levels of silica, as do some beaches in Florida, such as those in Siesta Key.
Minnesota also is known for its quartz.
Considering that quartz is one of the most common minerals found in the earth’s surface, your local rivers may be a better source for silica sand than you may have realized.
The problem is ensuring that the sand consists of 95% or more pure silica (silicon dioxide).
Even if there is enough silica present in your river sand, there may be impurities, such as clay particles, silt, shells, oil, decomposing plant and/or animal particles, and salt lurking as well.
Obviously, these will negatively impact the quality, durability, workability, and color of the glass.
The presence of minerals, metals, and metal compounds will affect the color of the resulting glass.
If you are not aware that they are present, you’ll likely be surprised by the color of your glass once it has cooled.
Tiny stones, pebbles, and bits of trash will cause problems as well if they are not thoroughly sifted out prior to firing.
In the following video, the young man attempts to make a blown-glass bottle using glass made from river sand that he harvested along the Mississippi River.
You can see for yourself what he wound up doing.
Source of the Sand
Of course, you can expect that sand that you source yourself from a local river will have impurities. That’s a given.
Some areas will be naturally purer than others, but contaminants are still likely.
GharPedia provides a list of field tests that will give you a general idea of the quality of the sand, or you can send a small sample of the sand to a testing facility to check for pureness.
For obtaining river sand, a better option may be to purchase it from a home improvement store or a local supplier.
In most cases the sand will have been washed, filtered, and kiln dried. Quality suppliers will also have the sand tested for impurities.
If you have trouble finding a local supplier, purchasing online is always an option. (I found a very reasonably priced 10-pound bag of pure silica sand on Amazon.)
It may be illegal for you to collect and bring home a bucket of river sand, depending on where you live.
Some states’ laws might not specifically prohibit removing sand, but others, such as Virginia, clearly do.
Check the laws pertaining to your area carefully before removing any sand, even if you think no one is watching. It’s not worth facing a hefty fine or jail time.
Problems You May Encounter Using River Sand
We’ve already discussed that impurities will likely be found in river sand that you collect yourself, but how will this directly affect your glass?
Well, the final color of the glass may have a greenish tint or other color depending on which metal compounds the sand contains.
For example, in the commercial production of colored glass, iron oxides are added to produce green or brown glass, and cobalt oxide is added to the mix to produce the widely popular deep blue glass.
To counter the effects of the metal compounds, you could add either manganese dioxide or sodium nitrate as a “decoloring agent,” according to Geology.com.
Fun fact: Red glass is produced by adding gold chloride, which explains why glass of this color tends to be more expensive.
Another problem you may have with river sand glass is the inability to shape or mold it as desired. Again, this is caused by impurities.
Attempting to blow glass made with impure sand will likely prove especially difficult.
One last thing to be aware of is the size of the sand grains.
Large-grained sand will take a lot longer to melt, sometimes even days, and may not be worth the trouble.
The smaller the grains, the faster the sand will melt and become glass.
Use a Respirator
Inhaling silica dust particles can cause irreparable damage to your lungs and respiratory tract.
When using river sand to make glass, the chances of dangerous exposure to high levels of silica dust are relatively low (unless you’re crushing it down to a finer grain) but why take the risk?
Frequent exposure to the fine dust particles and the fumes generated from the melting process can cause issues such as bronchitis, asthma, chronic obstructive pulmonary disease (COPD), silicosis, and even lung cancer.
It’s better to err on the side of caution by wearing a respirator to protect yourself.