Cobalt Naphthenate (CAS 61789-51-3)
| CAS No. | 61789-51-3 |
|---|---|
| Alias | Cobalt(II) naphthenate, Cobalt soap, Cobalt naphthenate solution |
| Category | Driers |
| Packaging | 200 kg |
Grade PID A-1 | Metal content 8±0.2%. Traditional surface drier for air-drying coatings, alkyd resins, varnishes, and printing inks.
Introduction
Cobalt naphthenate is the classic cobalt drier, and it is currently the most commercially interesting product in our drier range for a reason that has nothing to do with its performance. It is a cobalt drier that sits outside the 2-EHA restriction that catches every octoate grade we sell.
This is the 8% grade, supplied as a violet liquid in 200# solvent oil. It offers the fast surface drying that cobalt is specified for, with excellent solubility in aromatic and aliphatic solvents.
Physical & Chemical Properties
Purple to violet liquid. Metal content 8% ± 0.2% Co. Molecular formula Co(RCOO)2 where R is the naphthenic acid residue. Density 0.95 ± 0.03 g/cm³ at 20 °C, viscosity 100–200 mPa·s at 25 °C, flash point ≥45 °C closed cup, acid value ≤15 mg KOH/g, moisture ≤0.5%.
Applications
Traditional surface drier for air-drying coatings, alkyd resins, varnishes and printing inks. Typical dosage 0.1–0.5% on resin solids. Standard alkyd drying performance is surface dry within 4 hours and hard dry within 24 hours.
Regulatory status: why the naphthenate distinction matters
Start with what is not true. There is no EU ban on cobalt driers. ECHA's 2018 restriction proposal covered five inorganic cobalt salts, not cobalt carboxylates, and the Commission terminated it in April 2022. No cobalt substance appears on the REACH Authorisation List. COM(2025) 418 records no existing restrictions and no existing authorisations for cobalt substances.
Now the part that does bite, and the reason this grade is different from our octoates. The binding constraint on cobalt octoate is not the cobalt at all: it is 2-ethylhexanoic acid, harmonised Repr. 1B under CLP entry 607-230-00-6 and restricted under Annex XVII Appendix 6 by Commission Regulation (EU) 2023/1132 from 1 December 2023. That restriction reaches the whole octoate family and forces H360D labelling onto the finished paint.
Naphthenic acid is a different acid and is not caught by that listing. So a formulation built on cobalt naphthenate does not inherit the 2-EHA driver that its octoate equivalent does. That is a genuine difference in legal position, not a marketing angle, and it is the single most useful thing we can tell a formulator who is being pushed to reformulate away from cobalt.
Cobalt naphthenate itself has no harmonised CLP classification. Proposed CMRD 6 exposure limits of 0.01 mg/m³ inhalable and 0.0025 mg/m³ respirable remain a proposal, not adopted law. In the United States, 21 CFR 175.300(b)(3)(xxii) expressly lists cobalt naphthenate among permitted drier combinations.
Transport classification is UN 1268, Class 3, PG III, arising from the mineral spirits carrier rather than the metal carboxylate.
Handling & Storage
Flammable liquid. Store cool, dry, well ventilated, away from ignition sources. Consult the SDS.
Packaging
25 kg and 200 kg drums. Shelf life 12 months sealed. COA and SDS supplied.
Applications & Industries
Coatings & Paints
Metal driers (cobalt, manganese, zirconium octoate, naphthenates) and photoinitiators for coatings, paints, varnishes and industrial finishes — with COA & MSDS per batch.
Paints & Varnishes Driers
Metal soap driers for alkyd and oil-based paints: cobalt, manganese, zirconium, cerium octoates and naphthenates with verified metal content, COA & MSDS per batch.
Related Products
Cobalt Octoate
Cobalt Octoate (PID B)
Manganese Octoate
Cobalt Naphthenate (PID B-1)
Frequently Asked Questions
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MOQ depends on the product and specification. For most chemicals we can supply from 1 kg sample orders up to full container loads (FCL). Contact us with the product name and CAS number for a specific MOQ quotation.
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