HPMC & HEMC for Cement Mortar & Render – Retention & Workability
The rendering problem: water leaving too fast
Machine- and hand-applied renders fail in two familiar ways: the mortar dries before it cures because the substrate drank the water, or it sags and cracks because the rheology is wrong.
How the cellulose ether holds water and resists sag
A construction-grade cellulose ether addresses both. By retaining mixing water, HPMC and HEMC let cement hydrate through the full thickness of the render instead of only at the core, which is what gives a crack-resistant, well-bonded coat. The same viscosity build gives the anti-sag behaviour a thick render needs on a vertical wall.
HPMC or HEMC for your climate
Where HEMC (MHEC) earns its place is climate: its higher gel temperature keeps performance stable when walls and ambient air are hot.
Select and sample
Every viscosity comes in both NDJ and Brookfield, always with the test conditions – concentration, temperature, spindle and speed – so the number you check on arrival matches the one we shipped against. We recommend an application band and confirm the exact grade against your mix design..
Application evidence. Our selection guide is organised by what you are making, not by chemistry: tile adhesive, putty, gypsum plaster, self-levelling and rendering each have a recommended range, all quoted under the same test condition of 2% solution, pH 7, 20 C, Brookfield at 20 rpm.