Cement is the most widely used building material on planet Earth. As a result, there are a number of well-established safety principles that anyone handling this product should acquaint themselves with. The notes here are intended to take into account how artists, both professional & amateur might handle the materials involved and seeks to inform them of known, potential hazards.
To accomplish this, the various basic materials used in different cement-based formulations are defined and addressed individually.
Cement – A building material manufactured by grinding calcined limestone and clay to a fine powder, which can be mixed with water and poured to set as a solid mass or used as an ingredient in making mortar or concrete.
Cement is a very fine powdery material that, like any other such material, can easily get into the lungs and eyes. The fact that it contains a percentage of hydrated lime makes it hazardous to both and can also cause potentially painful damage to the skin. Particularly if it gets into an open wound or cut. It is best handled using chemical resistant rubber gloves, eye protection, and a particle mask. Care should be taken not only during mixing and placing but also during any finishing operations that produce dust.
Sanding, grinding, chipping or filing the material after it has hardened can yield a particularly nasty dust. If any sand is present in the mix, sanding and similar processes will produce silica dust in addition to the cement dust. And silica is far more hazardous than cement dust. Always wear a good quality particle mask or respirator and good fitting goggles when working any hardened cement-based mix.
Sand – Any fine, granular inorganic material that results from natural or manufacturing processes that reduce rock or stone into fine particles. (ASTM C125) That portion of an aggregate passing the No. 4 (4.76 mm) sieve and predominantly retained on the No. 200 (74 microns) sieve.
As a common element in most cement-based mixtures, sand may well represent the greatest hazard. While larger particles pose little threat beyond irritating the eyes, when in or accompanied by its’ own very fine dust, that threat level goes up exponentially. Silicosis (also known as “Grinder’s disease” and “Potter’s rot”) is a form of lung disease caused by inhalation of crystalline silica dust and is marked by inflammation and scarring in forms of nodular lesions in the upper lobes of the lungs. As noted above, the use of a good quality particle mask or respirator is necessary anytime a source for this form of dust is present.
Concrete Gravel – a pre-mix of torpedo sand and #6 stone. With the addition of cement, these are the principal materials used for producing most site mixed concrete. It is designed for smaller projects where the delivery of ready mixed concrete is not practical and the user can mix their own small batches of concrete.
Because this product is a combination that includes sand, it too has the potential to contain silica dust and should be handled accordingly. In theory, both this product and any “graded” sand has been washed to eliminate the dust, but in practice, much of what is sold has not been so processed. The safest approach is to always assume some such silica dust is present and act accordingly. And likewise, if you sand, grind or otherwise reduce this material, keep in mind you are creating a very fine silica powder in the process and wear a mask and goggles.
Admix or Admixture – Any material other than water, aggregates and Portland cement that is used as an ingredient of concrete and is added to the batch before or during the mixing operation. Generally incorporated to produce specific results such as freeze/thaw resistance, increased density, accelerated or retarded set, etc.
Because there are so many chemical admixtures available today, the only advice we can offer is this…
Always read and follow the manufacturer’s directions and safety precautions.
Acid Etch Stains – The products employed for use on any cementitious-based mixture whereby it may be rendered in color after curing. It is accomplished by means of the application of specially formulated acids containing various metallic salts that chemically react with the free lime in the cement producing a wide range of permanent colors that lightly penetrate into the surface. “Stain” is therefore somewhat of a misnomer.
The acid employed in these stains is a relatively dilute form of Hydrochloric acid but it must be respected and handled properly.
Below is a short list of “Do’s & Don’ts”:
- Avoid breathing the vapors and never, ever attempt to smell the material. As peculiar as this may sound, over the years I have actually witnessed several people sniff the bottle as if to see if it had “gone bad” or something. Be advised that this is not milk. It is Hydrochloric acid and in concentration, it has the potential to permanently destroy your sense of smell in a heartbeat. For that matter, sniffing any unknown material is downright foolish.
- Always use splash-proof eye protection when working with or handling this material.
- Never leave containers sitting open. The fumes can build up and concentrate and it also dramatically shortens its’ shelf life.
- Always work in a well-ventilated area to avoid any build up of fumes.
- Never leave a cup or other such working container sitting out where kids or pets might get into them. To children, it often looks like juice or Kool-Aid. And while most animals would instinctively avoid it based on the smell, either group could easily spill the material onto themselves.
- Always dispose of any leftover material or empty containers responsibly. Combining any left over material or rinsing the containers with a large volume of water will reduce its’ PH to a safe level. The addition of Baking Soda to the rinse water will further neutralize any remaining acid.
- If you ever decide to dilute any acid etch solutions, always pour the acid into the water. Never the water into the acid. Introducing water into any strong acid can result in an explosive reaction. Not an “explosion” per se, but a rapid boiling and expansion that will spray acid everywhere. Old-time Masons had apprentices recite the following mnemonic device until it became thoroughly embedded in their thinking…
“Do like you oughter’…add acid to water.”
You would do well to remember it yourself and apply it to any manner of acid & water mixing.
- Be careful to control the run off from any rinsing procedure. You can not only destroy the pH of the soil around your prized Tulips, but you will very likely wind up inadvertently staining any concrete downstream.
NOTE: I have worked with acid stains for many years and never suffered any ill effects from handling them. No burns, no vision loss and my sense of smell appears to have remained intact. But that is due in large part to taking the time to understand what it was I was dealing with. Feel free to consider that a healthy mantra for any new material you decide to work with.
Sealers – NOTE: For more information regarding Sealers, see the separate write up on this topic.
A group of liquid compounds specifically designed for the purpose of protecting cured concrete or any cement-based medium from surface wear or the intrusion of damaging environmental contaminants. They are also commonly used to create a specific surface treatment and enhance the coloration of the substrate to which it is applied.
They are commonly available in two basic formulations:
1. Water-Based Film Forming Sealants
2. Solvent-Based Penetrating Sealants
Water-based sealers, as the name implies, employ H²O as the vehicle to carry the actual sealer onto the surface. The water is a known element, however, you will have read and possibly research what the sealing component in any given brand might be before assuming any level of safety. With so many products available these days there are bound to be a few surprises.
Likewise with any solvent-based sealer. Nearly all manufacturers have their own proprietary blend of chemicals in order to secure patents or otherwise achieve some advantage over their competition, so you will simply have to read the labels carefully and follow their (hopefully) knowledgeable guidance.
NOTE: The general research that I have done on sealers indicates that once cured, both systems are considered non-toxic to fish and animals. It appears that if there are any potential hazards, they are present only when the materials are in a liquid state. However, experience would give rise to the suspicion that some degree of hazard would also present itself during the removal of any such material. If sanding or removing common paints and varnishes requires some caution, then my guess is that similar care should also be taken when removing these finishes as well.
Do some homework. Read a lot of labels. Think about what you are going to do before you jump in and do it. These are universal safety guidelines that apply to these materials as well as most others.
Cement-based media offers artistic advantages and opportunities that very few media can match. Learn to work with them properly and you will be rewarded.
Be careless…and, like so many other things in life, they can hurt you.