Industrial Manufacturing / Solution Family

Metalworking Amine Emulsifiers & pH Buffers

Alkanolamine pH builders, emulsifiers, and inorganic buffers for water-soluble metalworking fluids u2014 monoethanolamine, triethanolamine, and boric acid u2014 supplied in bulk.

Overview

Metalworking-fluid amines are alkanolamines that hold a water-solublencutting or grinding fluid at the right pH while doing several jobs at once: bufferingnacid drift, emulsifying oil into water, and protecting ferrous metal from flashnrust. Monoethanolamine (MEA, CAS 141-43-5) is the strong, low-cost pH andnreserve-alkalinity builder; triethanolamine (TEA, CAS 102-71-6) adds emulsificationnand yellow-metal-friendly corrosion control. Target a working pH near 8.8-9.2 fornmost soluble fluids and dose the amine to hold it as the sump ages.

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The genuine trade-off is chemical, not commercial. Alkanolamines give a sump longnlife and good corrosion protection, but with a nitrosating agent present, most oftenna nitrite-based corrosion inhibitor, secondary-amine content can form N-nitrosamines,na documented metalworking-fluid concern flagged by NIOSH. Primary amines such as MEAnform unstable nitroso species; residual diethanolamine in a tertiary-amine grade isnthe principal precursor. Do not combine nitrite inhibitors with amine-based fluids,nand confirm regulatory status for your application and jurisdiction.

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Boric acid (CAS 10043-35-3) rounds out the group as an inorganic pH buffer andnreserve-alkalinity aid, not an amine, and provides the mild biocidal action thatnhelps hold sump pH and limit spoilage. Keep total water hardness in view, becausenhard make-up water shifts both pH and emulsion stability. Monitor pH and refractometernconcentration weekly, and top up the amine package before pH falls below about 8.5nrather than after corrosion appears.

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Where it's used
  • pH control and reserve alkalinity in water-soluble cutting and grinding fluids
  • Oil-in-water emulsification for soluble-oil and semi-synthetic coolants
  • In-fluid ferrous and yellow-metal corrosion protection
  • Sump-life extension through buffering and microbial control
  • Neutralization of fatty acids in soluble-oil concentrate manufacture
Frequently asked questions
Does RawSource supply metalworking-fluid amines such as MEA and TEA in bulk?
Yes. RawSource sources monoethanolamine, triethanolamine, and boric acid in drums, totes, and bulk against an RFQ. Grade and concentration requirements are matched at quote.
Why are nitrite corrosion inhibitors not used with amine-based metalworking fluids?
Alkanolamines can react with nitrosating agents such as nitrite-based corrosion inhibitors to form N-nitrosamines, a documented metalworking-fluid concern flagged by NIOSH. Secondary-amine content is the principal precursor. Formulators avoid combining nitrite inhibitors with amine-based fluids. Confirm regulatory status for your application and jurisdiction.
What is the difference between MEA and TEA in a metalworking fluid?
Monoethanolamine (MEA) is a primary amine used mainly as a strong, low-cost pH and reserve-alkalinity builder. Triethanolamine (TEA) is a tertiary amine that also emulsifies oil into water and supports yellow-metal corrosion control. Many fluids use both, MEA for alkalinity and TEA for emulsification.
Is boric acid an amine?
No. Boric acid (CAS 10043-35-3) is an inorganic acid/salt used as a pH buffer, reserve-alkalinity aid, and mild biocide in metalworking sumps, not an amine. It is on the ECHA REACH SVHC Candidate List (toxic for reproduction); confirm regulatory status for your application and jurisdiction.
Disclaimer. Information on this page is provided for general reference and compiled from authoritative public sources (e.g. PubChem/ECHA). Values are typical and are not a guaranteed specification; the Certificate of Analysis (CoA) for the lot you purchase governs. Products are sold for industrial and professional use only. Nothing here is a medical, health, or efficacy claim. Always consult the current Safety Data Sheet (SDS) before handling, and confirm regulatory status, classification, and suitability for your application and jurisdiction.
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