Picking the right phenalkamine: a decision framework

Phenalkamine hardeners tolerate moisture, low temperature and marginal substrate preparation better than many classical amines. The choice still matters: the wrong grade can create problems with pot life, colour, viscosity or stoichiometry.

Use this framework to compare Unilite 7040, 7041, 7041X90 and 7057 against four properties that drive most marine and protective coating decisions.

Cure speed

Phenalkamines are generally faster-cure than classical amine adducts, but inside the line, the cure profile varies. Unilite 7077 (the adduct version) cures fastest; the pure phenalkamines (7040, 7041) are slower. Pick the slower grades when you need pot life for spray or brush application; pick the adducts when you're racing a dry-dock window.

Colour

If a colour-critical topcoat sits over the system, Unilite 7057 (Gardner 10) is the cleaner choice. The rest of the line sits at Gardner 17, which is fine under pigmented systems but visible under clears.

Viscosity

Unilite 7040 runs 2,000–4,000 cP at 25°C and is easy to handle. Unilite 7041 runs 20,000–50,000 cP, with better sag resistance once mixed. If 7041 is too thick to mix at site temperature, switch to 7041X90, the pre-cut version at 3,000–6,000 cP that gives the same cure profile with workable rheology.

AHEW

AHEW (Amine Hydrogen Equivalent Weight) determines your stoichiometry against the epoxy resin. The line spans 81 (7040) to 144 (7041X90). Make sure the stoichiometry is calculated from the AHEW of the grade actually being shipped.

Quick reference

If you are not sure, send the specification and site temperature profile. We will recommend a grade.