Q. After reading your “Advanced Brewing” column “In Search of Perfect Foam,” I am curious what is the best way to clean my beer glassware. If I don’t use a detergent like Dawn, what do you suggest?
Louie Strano
Via email 

Mr. Wizard says …

This is a great question, Louie. I may have written something in that column about foam that suggested household detergents like Dawn are problematic; but to clarify, they are not when the detergent is properly rinsed.

You, like other homebrewers and commercial brewers who work in taproom breweries and brewpubs, want extremely clean beer glasses to deliver the best looking glass of beer in a clean vessel. And you have lots of options when it comes to detergent selection. Commercial-strength caustic cleaners, milder chemicals like PBW, detergents specific to restaurant dishwashers, household products like Dawn, and even homemade sodium carbonate are all options. These options range in cleaning efficacy and have different safety considerations.

When selecting a cleaner, start by defining the task. Most beer glasses are soiled by beer residue and whatever the consumer’s lips transfer to the glass. Other soils that are often overlooked come from the cleaning/rinse water, detergent residues that need to be rinsed from the glass during cleaning, and soils that may be deposited on the glass surface during cleaning. This means that the ideal detergent can remove carbohydrates, protein, lipids, and mineral deposits, function in a wide range of water types, and be easily rinsed after the cleaning step. That’s a tall order.

Looking at this from a commercial brewer’s lens, caustics intended for tank cleaning are the first cleaners that come to mind because when one is accustomed to dirty fermenters, everything looks like a dirty fermenter. These chemicals are the hands-down winner when it comes to cleaning power because they are based on sodium and/or potassium hydroxide, which are great for organic soil removal, especially proteins and lipids, contain surfactants that help with soil dispersion and rinsing, and are sometimes equipped with chelating agents to sequester calcium and magnesium, thereby improving cleaning performance and minimizing water spots. A major problem with these products is they are dangerous and should only be used when wearing protective gloves and eye protection. While not a practical choice for glassware cleaning, they are the gold standard when it comes to cleaning efficacy and serve as a useful benchmark for cleaning.

A general cleaning fact that is helpful to know is the relationship between pH and soil removal. When liquid pH increases and becomes alkaline, proteins change shape and are more easily dissolved, and lipids are saponified, turning into water-soluble soaps. When alkaline cleaners are used without hand protection, fats from skin turn into soaps, feel slippery to the touch, and are rinsed from skin after cleaning, often resulting in dry skin. If these cleaners are repeatedly used without proper protection, dry skin will eventually crack and can become infected. Not good!

Although PBW, the long-standing cleaning standard in the homebrewing world, is less alkaline than heavy-duty caustics, it shares many of their cleaning strengths and works quite well for glassware. But what exactly is PBW? The answer can be found by referring to PBW’s Safety Data Sheet (SDS). Based on this legally-required document, we know that the key ingredients are: Disodium carbonate (30–60%), sodium percarbonate (10–30%), tetrasodium EDTA (5–10%), sodium metasilicate (1–3%), and trisodium MGDA or methylglycinediacetic acid (0.5–1.5%). Because PBW works great for cleaning beer glasses, let’s walk through this list of ingredients.

Sodium metasilicate, although a minor ingredient, is the heavy hitter in the ingredient list and is like sodium and potassium hydroxides; the main difference is that sodium metasilicate is slightly less alkaline. And it only makes up 1–3% of the total formulation. Disodium carbonate, commonly known as soda ash and made by heating baking soda, is an alkaline cleaner that has good cleaning properties, but works best when blended with other compounds, especially chelating compounds. It comprises 30–60% of the PBW formulation and its cleaning properties are boosted by the other ingredients.

Sodium percarbonate, the key ingredient found in OxiClean™ Free, acts in three different ways. When added to water it breaks down into sodium carbonate, providing alkalinity that helps with lipid removal, and hydrogen peroxide. Hydrogen peroxide is a chemical oxidizer that removes protein and acts as a bleaching agent; it is also a source of bubbles that help free deposits from the glass surface.

The last ingredient group, chelating compounds, is comprised of EDTA and MGDA. These compounds sequester calcium and magnesium ions found in hard water, maintaining alkalinity by preventing the formation of calcium carbonate and magnesium carbonate during use. They also prevent the deposition of these hard water salts on glass.

What makes PBW a much better choice for glassware washing is safety. Although PBW is a strong alkaline cleaner with a high pH when diluted to usage strength, about pH 11 at 3%, it is much safer than caustic-based cleaners with pH >13 at 3%. However, like other household cleaners intended for use on tougher soils, pH 11 cleaning solutions should be used with gloves.

Moving into the kitchen space, the two obvious choices are dish soaps like Dawn and products specifically intended for glassware cleaning in bar sinks. Referring to Dawn Ultra’s SDS, the key ingredients include alkyl sulfates, alcohol ethoxysulfates, amine oxides, and ethanol.

In a nutshell, alkyl sulfates and alcohol ethoxysulfates are anionic surfactants that are great at cleaning, dissolving fatty soils, and dispersing the liberated soils into the cleaning solution. They are also very foamy. One weakness that these anionic surfactants have is they don’t work well when pH falls.

Amine oxides, commonly called amphoteric surfactants, have both hydrophobic and hydrophilic parts of the molecule. Like anionic surfactants, they clean, dissolve, disperse, and produce lots of foam, but they are not as effective and are considered boosters. The strength of amphoteric surfactants is their ability to work well over a broad range of pH.

Finally, ethanol is used as a solvent to keep all of the ingredients, including dyes and fragrances not included in the SDS, uniformly distributed in the concentrate. Fragrances are certainly something that can cause issues with beer glasses if not completely rinsed from the glass surface.

One key difference between a cleaner like Dawn and the other cleaners discussed so far is safety. Designed for use in the kitchen sink, household dishwashing solutions do not require hand or eye protection. Dawn’s formulation is sounding pretty good!

But there is a hitch; detergents like Dawn do not contain chelating compounds or rinsing aids often used in conjunction with very foamy cleaners to help remove the foam. These are the reasons that household detergents are not the ideal glass cleaner. The absence of surfactants allows calcium and magnesium water spots to form when glasses are air dried and the lack of a rinsing aid, the sort of thing that dishwasher drying agents contain, means that some of the detergent and soils from the cleaning liquid can be left behind. These residues can make glasses appear milky and damage beer.

In practice, thorough rinsing can make up for what detergents like Dawn lack. You can also use a dilute acid solution of something like citric acid or white vinegar as a rinse aid. But that’s another step and most people washing beer glasses are not going to turn glassware cleaning into a 3-step process of pre-rinsing, cleaning/rinsing, and final rinsing.

The last tool to consider is a detergent designed for use in bar sinks. Because most municipal and state health codes require a final sanitize step, bars typically use 3-sink systems behind bars for manual cleaning. The first sink is a dump sink, the second sink contains the pre-rinse/cleaning solution, and the third sink contains a sanitizer — thankfully this model is not needed at home.

Bar sinks can be hostile on everything that passes through them because of the range of soils found on dirty glassware, including fats from cream-containing drinks, greasy bar foods, and lipstick, and the number of glasses cleaned before a fresh sink of cleaner is prepared. The third sink is the real problem for beer lovers. It rinses detergent and soil from glasses carried from the second sink and contains a sanitizer that can handle the organic load. The most common options are quat-based products or chlorine bleach. Both sanitize effectively, but quats kill foam, and chlorine bleach often leaves glasses smelling like a swimming pool. And neither help rinse the stuff carried into the sanitizer bath from the dreaded sink #2!

There are hundreds of detergents sold into bars and restaurants, so I picked one at random with a cool name: Beer Clean Low Suds Glass Cleaner. When used in a 3-sink system, this one detergent is expected to hold up to dirty glasses plunged repeatedly into the sink while cleaning brushes scrub glass surfaces. According to its SDS, the ingredients required to be disclosed are sodium citrate, sodium sesquicarbonate, sodium hydroxide, and amines, c12-14-tert-alkyl, ethoxylated propoxylate. Let’s decode.

Sodium citrate acts as a chelating agent and buffers the pH in the 7–9 range. Sodium sesquicarbonate is also a chelating agent and is a mild alkaline cleaner that is like the sodium carbonate found in PBW but not quite as strong. The mouthful listed as amines, c12-14-tert-alkyl, ethoxylated propoxylate are nonionic surfactants that help disperse soils and aid in rinsing. And finally, sodium hydroxide is present in small amounts and is the main source of alkalinity. As it turns out, this cleaner I randomly selected and decided to cover last has some very useful properties that explain how it lives up to the challenges of a second bar sink.

So what are the takeaways? Here is my summary:

1.   Commercial products, whether intended for use in the home kitchen, homebrewery, bar sink, or commercial brewery, lack detailed ingredient labels. However, Safety Data Sheets (SDS) are required and are easily accessible through a simple Google search. There is much to be learned by studying a product’s SDS.

2.   The best cleaners contain alkaline cleaners and boosters, chelating agents, surfactants, and rinsing aids.

3.   Some cleaners require PPE (personal protective equipment) to safely use and others do not. Beer glass cleaning is something where PPE should not be required.

4.   All the info in this answer can also be used to evaluate these cleaners for other uses in the homebrewery.