The grain texture of leather after tanning
If the waterproofing finish on leather does not form a continuous film, water penetrates inward as soon as it lands, and the grain swells and deforms once it has taken up moisture; if the spray rating is pursued at all costs, the coating is laid on too thick and the hand turns stiff, so wearing comfort and water repellency are hard to reconcile.
Chemi Tech supplies water repellents for the waterproofing finish of leather and synthetic leather, drawn from the water repellent KMF-4101 series; the make-up of the finishing liquor is set by the leather type, the treatment method and the finishing process. KMF-4101 is designed for the water-repellent finishing of leather, forms a continuous film on the grain, and holds its repellency steadily; the KMF-4102 of the same series suits finishing that asks more of both repellency and hand. Chemi Tech verifies repellency against the leather type and the finishing process, and gives the customer a fitted water repellent.
Advantages of Chemi Tech Water Repellents
Chemi Tech water repellent KMF-4101 series is built around the water repellency of leather, forms a continuous film on the grain, and water beads rest on the surface without penetrating; moreover, the hand stays soft and does not turn stiff or rough, so wearing comfort is not disturbed; in addition, it is compatible in the same bath with the auxiliaries commonly used on leather, so the finishing sequence needs no splitting; and the repellency lasts, staying within the usual threshold after repeated washing.
Industry Pain Points and Solutions
The difficulty of leather waterproofing lies in the fact that a water-repellent film and a soft hand are hard to have at once; the consequence is that the spray rating passes while the hand turns stiff, or the hand stays acceptable while the repellency falls short.
Leather taking up water and letting it penetrate inward is a major pain point. When some finishing agents fail to form a continuous film, water penetrates inward as soon as it lands and the grain swells once it has taken up moisture. Chemi Tech recommends dosing the continuously film-forming KMF-4101 into the finishing liquor, so that the film on the grain stays continuous and does not easily break down.
The stiffening of the hand comes next. When the coating is laid on too thick the repellency holds but the grain turns stiff, and wearing comfort falls off. KMF-4101 from Chemi Tech is designed with repellency and hand weighed together, so the film on the grain stays continuous without stiffening.
The last problem lies in compatibility in the same bath. Leather finishing often runs in the same bath as fatliquoring and softening auxiliaries, and if the auxiliaries are not compatible the finishing effect and the hand both suffer. Chemi Tech runs KMF-4101 against the common auxiliaries in same-bath comparisons, so the finishing sequence needs no splitting.
Typical Operating Conditions and Verification
Customer: a leather processing enterprise in Fujian, for its waterproofing finishing line of leather.
At this plant the leather took up moisture and the grain swelled after the waterproofing finish, the hand turned stiff, and the customer reported a drop in wearing comfort. The solution Chemi Tech water repellent gave for the situation was: taking the leather type and the treatment method into account, choose the KMF-4101 series, and re-calibrate the finishing liquor concentration and the curing conditions. After the finishing line was adjusted, the grain held its repellency steadily, the hand came back to soft, and the spray rating returned within the customer's threshold.
Frequently Asked Questions
Once leather has had a waterproofing finish, will its breathability and hand be affected?
It is indeed possible, since some finishing agents lay on too thick a film, and the repellency holds while the grain stiffens and the breathability falls. Chemi Tech has verified the repellency and the hand of KMF-4101 against the finishing conditions, and only recommends it for the line once the film-continuity data holds steady. The finishing liquor concentration is set by the leather type and the weight per unit area, and Chemi Tech gives its recommendation after repellency and hand comparisons.