Grain defects are often blamed on liming or finishing, but they start in the chrome bath — in how fast the pH came up. Why gradual basification matters.
Chrome tanning is two jobs in one bath. First the chromium has to get all the way through the pelt; then the pH is raised so it fixes to the collagen. Get the order wrong — fix before you have penetrated — and the leather tells on you later.
Why the pH curve matters more than the endpoint
Basification is usually done with sodium bicarbonate or a similar alkali. The difficulty is not the target pH, it is the journey. Alkali added to a running drum dissolves faster than it disperses, so the float sees a local spike well above the intended figure. Chromium fixes hard at the surface it happens to be touching at that moment, before it has reached the centre of the cross-section.
The result is a case-hardened band: chrome-rich near the grain, chrome-poor in the middle. It reads as loose, drawn or wrinkled grain, uneven colour after dyeing, and batch-to-batch variation that is hard to trace because the basification step itself looked fine on paper.
What a buffered basifying agent does differently
NEOMAG-90 is a buffered compound that raises pH gradually rather than in steps. It releases alkalinity slowly enough that the float stays near-uniform as it climbs, so penetration finishes before fixation takes hold. Because the curve is controlled, the endpoint is repeatable — the same offer gives the same wet blue next week.
- →No pH spiking — gradual basification instead of sudden jumps at the point of addition.
- →Uniform colour — even chrome distribution removes a common cause of lot-to-lot variation.
- →Protected grain — avoids the looseness and wrinkling that follow surface over-fixation.
- →Firm wet blue with smooth, tight grain, and no over-basification at the correct dosage.
- →Economical — a cost-effective replacement for traditional alkalis in the same process slot.
Reading it back from the leather
If your wet blue shows a chrome-rich rim on a cut cross-section, or colour that goes patchy on aniline work, look at basification before you change your retanning. A slower pH curve is one of the cheapest quality corrections available in the tanyard: same drum, same schedule, different alkali.
Where it sits in the process
NEOMAG-90 works at pH 11.0–13.0 as supplied and is dosed into the chrome bath at the basification stage — after pickling and chrome offer, before samming. It is ZDHC Level 3 conformant, like the rest of the Kelvin Care Leather range, and the technical data sheet, certificate of analysis and safety data sheet travel with every order. See the NEOMAG-90 product page for the full specification and key advantages.