Polyester Buttons: Cast Sheet, Effect Families, Sizes and MOQ Logic

How are polyester buttons made? Cast sheet, not injection

Unsaturated polyester resin is mixed with a catalyst and the colour, poured into a sheet mould frame, cured, then cut: blanks are punched on a cutting die, turned, drilled and polished. There is no steel mould anywhere in the process. A new size or shape means a new cutting die — days, not weeks — which is why cast-sheet polyester is the fastest custom button to develop and the easiest to re-size mid-season when a fit changes after the PP sample round.

The second half of the sentence is what buyers miss: cast sheet and injection moulded are not the same button. Injection moulded buttons are shot into a steel mould per shape; cast-sheet buttons are poured first and cut afterwards. The effects below only exist because the colour sits through the whole sheet — that is a cast-sheet capability, and it cannot be replicated by injection.

The effect families, and what each one is called on a trim card

Buyers meet cast-sheet polyester under a dozen trade names. The words matter, because the effect drives both the MOQ and the approval route:

On a cost sheet the plain body is written POLY; the effect word has to appear or the supplier quotes a different button. Sending a photo in the RFQ is not a specification — write the effect family and a Pantone or approved sample reference, and ask for a counter sample against it before the quotation is signed off.

Sizes and constructions: ligne, holes and shank

Cast-sheet polyester covers the widest size band in the trade — most effect families run 14L–40L, plain colour bodies to 48L, and larger sizes are quoted on request because they are cut from the same sheet with more waste around each blank.

Constructions are 4-hole, 2-hole and shank. The hole count is a sewing-line decision as much as a design one: 4-hole takes a cross-stitch and holds a heavy button flatter; 2-hole suits a straight bar tack; shank lifts the button off a thick cloth so the placket does not pucker. Put the construction on the tech pack, not just the diameter — a 20L 4-hole and a 20L shank are different parts.

MOQ: why the effect families cost more per colour

MOQ on cast-sheet polyester is quoted per size and per colour, in gross (1 G = 144 pieces). At 14L, plain colour families start at 115 G; rod-effect families such as faux horn start at 200 G, because the streak pattern is set per colour batch and a short run cannot hold the pattern consistent across the lot. The full ladder from 14L to 48L sits on the product page.

Below-MOQ orders are accepted with a fixed surcharge calculated per size and per colour — the figure belongs in the quotation, not on this page. Ask for it as a line in the RFQ reply so the comparison between two suppliers is like for like.

Buyer pitfalls: how polyester button orders go wrong

Shade drift between lots. The most common chargeback on this material. Control it with a lab dip per colour and a Delta E limit against the approved sample, and keep the approved reference on file for the repeat order — the same discipline cast-sheet effects need on every season.

Pinholes and voids on the face. Cast sheets can trap air; the defect shows after polishing, not before. Screening belongs at the blanking stage, and the AQL inspection level on the PO is what enforces it.

Writing 'custom mould' for a cast-sheet button. There is no mould to amortise — a supplier who quotes a mould charge for a polyester button is either quoting a different process or padding the tooling line. The correct wording is cutting die or punching die.

Heat, not water, is the limit. Cast polyester survives normal laundering and a warm iron, but a pressing line running hot will mark it. If the garment goes through automatic pressing, say so in the RFQ — that sentence is the difference between polyester and urea.