Acid Wash and How We Actually Do It on the Floor

There are a few defects associated with acid wash, and understanding what causes each one is how we avoid them — and how a buyer can tell a factory that knows the process from one that's guessing.

Crocking – a defect that consists of a transfer of dye from one surface of the item to another during wear – happens when the neutralization phase or the softening process ends prematurely, resulting in loose dye that is not properly set in the material. We make sure all these processes are completed to the full cycle time instead of being ended early, since this is a defect a buyer will catch in the finished goods, not one that can be fixed after the fact.

Backstaining – where the dye that has been lifted transfers back to other locations of the garment, or worse, other garments – occurs because of the drum being overloaded and/or the liquor ratio that is insufficient to carry away the excess dye. We limit the loading per drum instead of maximizing the number of items we can wash per cycle.

Chlorine damage and yellowing – this is where the garment takes on a brittle feel and yellowish coloration in a couple of weeks after the item was shipped – is usually caused by either an oxidizer being present in the item due to the incomplete neutralization process, or too long a tumble resulting in over-removal of the dye. This is a defect that is most likely to show itself after the item has already been accepted by the buyer; that is why we have set rinse times instead of adjusting them per cycle.

Pinholes and thin spots – this is a defect that includes small holes and thin spots of fabric, usually found at the seams or around pockets – is caused either by the stone ratio being too high or the tumble time going beyond the intended grade. That is the risk that we take by washing the garment to the point where the fabric strength is being compromised in order to increase the contrast.

None of these defects are very rare – every factory that uses acid wash will be able to identify them. Usually, the difference between factories that occasionally produce these defects and those that rarely do lies in whether the neutralization and rinse steps are run to full cycle time every batch, or cut short to save a few hours.

The oxidizing agent we use in acid washing processes is potassium permanganate, one of the chemicals currently under scrutiny by the industry due to being included on the candidate watch list of the ZDHC Manufacturing Restricted Substances List. Controlled dosing and closed handling of the chemical is the default standard we apply to this operation rather than an option, and the waste effluents are treated on-site before their discharge.

There is a move towards the development of synthetic or reused stone abrasives, including recycled rubber or PU-based abrasives, resulting in a similar abrasion effect with less pumice dust in the effluents and less wear and tear of the drums used. We have not adopted this technology across all our operations yet, as natural pumice is more effective in giving contrast to the fabric surface, but when a client specifically requests the process, we conduct trials with synthetic material and walk you through its shortcomings.

This page covers how the finish is made. If you already know which garment you want it on, the acid wash hoodies and acid wash jeans pages cover sizing, MOQ and ordering specifics for each.