Safely etching concrete pool coping

[newpoolj]

I'm planning to apply some NewLook EnduraCool stain soon to my pool deck and patio, and as part of their prep, they recommend etching the concrete to open it up to better absorb the stain. They sell an etching product that is supposedly eco friendly (here's the SDS and TDS), but I'm hesitant to use it around the inside of the pool coping without either a plan to keep it out of the water (if that's even possible) or a good idea that it's safe to rinse into the pool water.

Any advice on how to etch the inside of a pool coping, what product to use, and how to keep the product out of the pool as much as possible?

 

[JamesW]

From Claude:

Based on the information provided in the SDS and the product's purpose as a concrete cleaner, degreaser, and etching material, I can suggest some likely candidates for the "Organic Acidic Salt" component, though I can't definitively identify it without more information.
The most likely candidates would be:

Citric acid salts (sodium citrate, potassium citrate) - These are commonly used in biodegradable cleaning products and have mild etching properties.
Glycolic acid salts - Effective for etching concrete surfaces and commonly used in concrete preparation products.
Lactic acid salts (sodium lactate, potassium lactate) - Biodegradable and effective for cleaning and mild etching.
Gluconic acid salts - Often used in concrete cleaners due to their chelating properties and ability to remove mineral deposits.
Acetic acid salts (sodium acetate) - Though less common in professional-grade products, they can provide mild etching capability.

Given the product's pH range (1.0 to 2.0) mentioned in Section 9 and its purpose as a concrete etchant, the organic acid salt is likely present in its acidic form rather than fully neutralized. The fact that the product is marketed as biodegradable further suggests citric, lactic, or gluconic acid derivatives are the most probable candidates.
Without laboratory analysis or more detailed information from the manufacturer, it's not possible to identify the specific organic acidic salt with certainty.

 

[JamesW]

Likely Candidates for Organic Acidic Salt:
Based on the above, here are the most likely candidates:

Sodium Citrate (or Citric Acid Salt):
Chemical: Sodium citrate (e.g., monosodium citrate, CAS 18996-35-5) is a salt of citric acid, an organic acid found in citrus fruits.
Properties: Mildly acidic in solution (monosodium citrate has a pH-lowering effect), biodegradable, and commonly used in cleaners. It can etch concrete by reacting with calcium compounds.
Fit: Matches the biodegradability, mild irritation profile, and acidic nature. The concentration (5-12.5%) could achieve a pH of 1.0-2.0 in combination with water and other ingredients.
Potassium Bitartrate (Cream of Tartar):
Chemical: Potassium bitartrate (CAS 868-14-4) is a salt of tartaric acid, an organic acid from grapes.
Properties: Acidic in solution (pH around 3-4, but can be formulated lower), biodegradable, and used in cleaning products. It can dissolve mineral deposits, supporting concrete etching.
Fit: Plausible, though its pH effect might be less aggressive than required unless paired with another acidifying agent. Mild odor and safety profile align with the SDS.

1. Sodium Glycolate (or Glycolic Acid Salt):
   • Chemical: Sodium glycolate (CAS 2836-32-0) is a salt of glycolic acid, a small organic acid.
   • Properties: Glycolic acid and its salts are biodegradable, strongly acidic (pH can drop to 1-2 in solution), and used in industrial cleaners and concrete etching products due to their ability to chelate metal ions and dissolve scale.
   • Fit: A strong candidate due to its etching capability, biodegradability, and alignment with the pH range. The mild irritation profile fits, as glycolic acid is less corrosive than mineral acids.
2. Sodium Lactate (or Lactic Acid Salt):
   • Chemical: Sodium lactate (CAS 312-85-6) is a salt of lactic acid, produced by fermentation.
   • Properties: Biodegradable, mildly acidic in solution, and used in eco-friendly cleaners. It can contribute to pH reduction and cleaning action.
   • Fit: Possible, though lactic acid salts are less commonly used for etching compared to citric or glycolic derivatives. The pH might need enhancement to reach 1.0-2.0.

Most Likely Candidate:​

Among these, sodium glycolate or a related glycolic acid salt stands out as the most likely candidate:

• It provides the strong acidity needed for a pH of 1.0-2.0 at 5-12.5% concentration.
• It is biodegradable and aligns with the product’s eco-friendly branding.
• It is effective for concrete etching and degreasing, consistent with the product’s purpose.
• Its mild irritation and toxicity profile match the SDS hazard categories (Acute Toxicity Category

• 4, Skin Corrosion Category 3, Eye Irritation Category 2B).

Sodium citrate is a close second, widely used in biodegradable cleaners, but it typically yields a less acidic pH unless formulated with additional acid, which isn’t explicitly indicated.

Conclusion:​

The most likely candidates for the "Organic Acidic Salt" in the 3-in-1 Prep product are sodium glycolate (from glycolic acid) or sodium citrate (from citric acid), with sodium glycolate being the strongest match due to its etching strength and pH-lowering capability. Without a CAS number or further chemical analysis, this remains an educated inference based on the SDS data.

 

[JamesW]

Best Guesses Based on SDS and Functionality:​

The most likely candidates are sodium citrate, sodium gluconate, or sodium lactate, as these are:

• Biodegradable
• Water-soluble
• Mildly acidic to acidic in behavior (depending on concentration)
• Common in concrete-safe cleaning or etching agents

The exact identity is proprietary ("N/A" CAS), but its functional role and the SDS characteristics strongly support one of these options.

Most likely, the “Organic Acidic Salt” is a proprietary blend of citric acid and its salt (like sodium citrate). It would meet all the criteria:

• Biodegradable
• Capable of etching concrete
• Reasonable safety profile
• No CAS because it’s a mixture