WET END - SYNTANS (Liquids)

What liquid wet-end syntans are

Liquid wet-end syntans are retanning, neutralizing and filling polymers supplied as liquids for the dye-house after chrome (or on wet-blue). They adjust pH safely, fill empty areas, tighten or keep grain fine, and set lightfastness and handle before fatliquor and dye. Dyna Glycols manufactures the VENTAN liquid series: neutralizing aromatic sulphonates (LNS), acrylic retans (RE, RT), maleic-acrylic (MA), and protein/polypeptide fillers (VEF, VPF).

Liquids are chosen when the tannery wants easy dosing, no dust, and polymers that are already in solution. Acrylics give fullness and grain tightness with good lightfastness; acidic acrylics (RT) plump in acid media; neutralizing syntans buffer so grain does not blow; protein fillers upgrade loose flanks but may dull pale shades. The right liquid syntan is a function of article (upper, upholstery, nappa, suede) and of the pH window of the process.

How Dyna Glycols manufactures liquid wet-end syntans

Acrylic and maleic-acrylic solutions are polymerised and finished to agreed solids and pH. LNS is a blend of aromatic sulphonic acid salts with buffers. Protein fillers are polypeptide and aromatic sulphonate blends or modified protein at about 47–50% solids.

Each grade has a characteristic pH: RT is strongly acidic (about 2–3.2); LNS near neutral; MA slightly alkaline; VEF/VPF around 7–7.5. That pH is part of the process design, not an accident of storage.

Typical grades in this range

Match the job: neutralize, acrylic retan, acidic acrylic, or protein fill. Then open the product page for % on shaved weight.

• VENTAN LNS — liquid neutralizing syntan; aromatic sulphonates with buffers; grain-tight neutralization
• VENTAN RE — aqueous acrylic retan; fullness, fine tight grain, lightfast, buffable
• VENTAN RT — acidic acrylic retan; selective fill, plump in chrome, best in acid medium
• VENTAN MA (liquid) — maleic-acrylic; upholstery, wet toggling, plump, lightfast
• VENTAN VEF — polypeptide/aromatic sulphonate filler; loose areas; not for white/pale
• VENTAN VPF — modified protein filler/softener; nappa, milled, round handle
• VENTAN F — liquid pre-tanning syntan (on request)

Where liquid wet-end syntans are used

Neutralization of shoe upper: LNS at about 1–4% on shaved weight, low astringency, buffering so over-neutralization is avoided. Then acrylic RE (corrected grain 3–4%, upholstery 2–3%) for tightness and buffing.

Upholstery and wet-toggle articles: MA liquid 3–5% after neutralization. Upper and drum-dyed cow: RT 2–5% depending on article, in acidic conditions. Nappa and milled: VPF 4–6% for selective fill and milling uniformity.

Soft aniline and side leathers that can accept a darker crust: VEF 5% (or more on suede splits and sheep clothing suede) to fill and level dye. Do not use VEF on white programmes.

How to specify liquid wet-end syntans

State article, tannage, target handle, lightfastness, and whether filling of bellies is the main problem. Give the neutralization pH you must hit. If wet toggling is required, name MA.

Share the current liquid syntan solids and pH if a match is required. Acrylic vs protein vs neutralizing must not be confused on the purchase order.

Quality, documents and supply

Lots are released against appearance, pH, solids and solubility. SDS and COA follow verification. Retan effect is judged on crust after the tannery’s dye and fat, not on a beaker gel.

Store frost-free. Typical shelf life six to twelve months depending on grade (RE lists 12 months). Mix viscous grades before sampling.

Practical notes on liquid wet-end syntans

LNS is not a retan filler. Its job is safe neutralization with grain smoothness. Using only LNS and skipping acrylic or vegetable will leave empty leather.

RE is the general lightfast acrylic for tightness and buffing. RT is the acidic cousin for selective fill and plump; it wants an acid medium. Do not expect RT to behave like RE at pH 6.

MA liquid and MA powder are the same polymer family in different form. Upholstery shops that dissolve powder to 30–40% can compare with the ready liquid.

VEF dulls shade and is excluded from white/pale. VPF is the filling/softening protein when round handle and milling matter. They are not interchangeable.

Compatibility: RE is written as compatible with syntans, vegetable extracts, anionic dyes and fatliquors. Still add in the order the process sheet states; dumping acrylic onto a very cationic surface can precipitate.

Dyna Glycols can sample LNS + RE + MA + VPF as a dye-house set for a new article development.

Ordering and evaluating liquid wet-end syntans

Dyna Glycols supports liquid 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 liquid 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 liquid 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 liquid 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 liquid 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 liquid wet-end syntans, write that method on the order so the COA speaks the same language.

Custom lots of liquid 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 liquid wet-end syntans matches the first approved drum.

Storage of liquid 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 liquid wet-end syntans has frozen or separated in transit, homogenise it before charging a batch; do not decant only the liquid layer.