WET END - SYNTANS (Powders)

What powder wet-end syntans are

Powder wet-end syntans are spray-dried retanning, neutralizing, rechroming, resin and replacement tannins used on wet-blue and in vegetable routes. They are dust-free flowing powders with low moisture, dissolved in the dye-house float. Dyna Glycols manufactures the VENTAN powder series: rechroming (RCS), dye-levelling (DPS), neutralizing (NNS, PNS), pretanning (PTS), phenolic replacement (RPS, WRS white), amphoteric replacement (AMS), melamine resin (MRS, MRS-S), dicyandiamide resin (DRS) and maleic-acrylic powder (MA).

Powders give the tannery a wide chemistry set in one family name: chrome character from RCS, safe neutralization from naphthalene or phenolic buffers, white/bleach from WRS, resin fill from melamine or DCDA, and general phenolic replacement from RPS. Choice depends on whether the problem is chrome affinity, dye penetration, empty flanks, buffing, or a white article.

How Dyna Glycols manufactures powder wet-end syntans

Syntans are condensed or polymerised, then spray-dried to about 5% maximum moisture as free-flowing powders. Release tests include appearance, moisture, pH of 10% solution and solubility (some resin grades are hazy with sediment, which is normal on the TDS).

MRS-S is the clear-solution melamine variant versus standard MRS which is hazy. MA powder can be dissolved to 30–40% to mimic the liquid MA. Colours range from white (WRS, MA) through green (RCS chrome character) to brown resin grades.

Typical grades in this range

Group the powders by function, then dose on shaved or pelt weight as each page states.

• VENTAN RCS — rechroming syntan; green powder; chrome character, tight grain, dye affinity
• VENTAN DPS — dye-levelling and dispersing syntan for vegetable and resin tannins
• VENTAN NNS — naphthalene neutralizing syntan; buffered, low bleach of shade
• VENTAN PNS — phenolic neutralizing syntan for soft leathers and compact processes
• VENTAN PTS — phenolic pretan for vegetable tannage; also mild chrome retan/bleach
• VENTAN RPS — general phenolic replacement syntan
• VENTAN WRS — white/bleaching phenolic replacement for white leather
• VENTAN AMS — amphoteric replacement; softness and brilliant dye
• VENTAN MRS / MRS-S — melamine resin; fullness, buffing, dye level
• VENTAN DRS — DCDA resin with fillers; empty parts, round handle, buffing
• VENTAN MA powder — maleic-acrylic; upholstery wet toggle, plump

Where powder wet-end syntans are used

Rechrome wet-blue with RCS at about 2–4% on shaved weight before neutralization to keep chrome character and tighten grain. Neutralize with NNS (2–3% upper) or PNS (1–3% upper; 3–4% compact cow upper) depending on softness needed.

Replacement retan: RPS 4–6% for upper, suede, nubuck and pastels; WRS 5–8% when the article must be white. Resin fill: MRS 3–6% by article; DRS 2–5% for empty parts. AMS 2–8% where amphoteric behaviour and milling grain evenness are wanted.

Vegetable pretan: PTS 3–5% to speed vegetable penetration with a pale, undrawn grain. Dye problems: DPS 1–2% for level dyeing and resin/vegetable dispersion. Upholstery: MA powder 3–5% after neutralization.

How to specify powder wet-end syntans

Name the function (rechrome, neutralize, replace, resin-fill, white, dye-level), the article, and formaldehyde or colour constraints. MRS is melamine-formaldehyde based; state if formaldehyde on the article is limited.

If matching a competitor spray-dried syntan, send pH of 10% solution, moisture and whether the solution is clear or hazy (MRS vs MRS-S).

Quality, documents and supply

Lots are released against appearance, moisture, pH of 10% and solubility notes. SDS and COA follow verification. Dissolve as the TDS states; some resins leave sediment which is accepted on that grade.

Store dry; typical shelf life 12 months. Close bags after use. Do not use wet, caked powder in a critical white article.

Practical notes on powder wet-end syntans

RCS is a masked chrome-complexed rechrome, green in the bag. It is not a replacement phenolic. Using RCS as if it were RPS will not bleach to white; use WRS for white.

NNS vs PNS: naphthalene vs phenolic neutralizing. PNS is positioned for very soft leather and compact processes with grain smoothness; NNS emphasises buffered neutralization without bleaching dye.

WRS vs RPS: both phenolic replacement; WRS is the bleaching/white grade. Pastel programmes often still use RPS; true white upper uses WRS.

MRS vs DRS: melamine vs dicyandiamide resin. Both fill and help buffing; DRS is called out for empty parts and a round medium-soft handle; MRS for fullness, softness, elasticity and dye level.

AMS is amphoteric and can work at lower and higher pH, with brilliant dyeing. It is the grade to trial when a purely anionic replacement kills shade brilliance.

Dyna Glycols can supply a powder kit (RCS, NNS, RPS, WRS, MRS, DRS, AMS, DPS, MA) so a new dye-house can map functions without mixing competitor chemistries in the first trials.

Ordering and evaluating powder wet-end syntans

Dyna Glycols supports powder wet-end syntans with laboratory samples, current SDS, TDS and COA from the Kandla SEZ manufacturing network. Tell us the intended application, the substrate, the required moles or molecular weight, and any limits on colour, odour, cloud point, hydroxyl value, pH or residual feedstock. A matching catalogue grade of powder wet-end syntans in the Leather Chemicals family can then be confirmed, or a custom batch can be planned on the ethoxylation, esterification or related plant.

When you evaluate powder wet-end syntans, send the competitor grade if one exists, the bath or emulsion conditions, and the tests your receiving laboratory will run. Pack options for powder wet-end syntans typically include drums, IBCs and bulk where the viscosity and melting point of the selected grade allow safe handling from the Leather Chemicals manufacturing line.

A first order of powder wet-end syntans is easier when the purchase specification lists identity tests, not only a local trade name. Hydroxyl value, saponification value, acid value, cloud point, pH, water, colour and appearance are the numbers the Kandla QA laboratory can lock. If your QC uses a different solvent or a different cloud-point electrolyte for powder wet-end syntans, write that method on the order so the COA speaks the same language.

Custom lots of powder wet-end syntans are quoted after the hydrophobe or acid/alcohol pair, the target analytical window, the annual volume and the pack. Pilot batches are available when a catalogue point in the Leather Chemicals range is close but not exact. Once a trial lot is approved, that TDS should be frozen so the tenth delivery of powder wet-end syntans matches the first approved drum.

Storage of powder wet-end syntans should follow the SDS: keep containers closed, protect hygroscopic grades from moisture, and warm high-melt or high-mole grades until uniform before sampling. FIFO rotation protects colour and odour. If a drum of powder wet-end syntans has frozen or separated in transit, homogenise it before charging a batch; do not decant only the liquid layer.