How to Approve Fabric Lab Dips Before Bulk Dyeing

Introduction

A sage-green sports bra and a pair of leggings can look like a perfect match in the sample room, then look noticeably different under store lighting. If the two pieces use different fabrics, approving each swatch on its own can miss the problem.

A fabric lab dip gives brands a chance to settle on a shade before bulk dyeing. For a matching set, the approval process should also answer two practical questions: Do the components look right together, and can the bulk fabric match what was approved?

What Is a Fabric Lab Dip?

A lab dip is a small piece of fabric dyed in a laboratory to match an agreed color target. The mill may submit several labeled options so the buyer can select the closest match or request a specific correction.

A lab dip is normally used to approve a solid dyed shade. If the design is printed, ask for a print strike-off on the intended base fabric so you can review the artwork, colors and print placement together.

Start With the Right Color Reference

Send the supplier a physical color swatch or a complete color reference code, including its suffix where applicable. A screenshot can show the general direction, but it should not be the only reference used for approval.

Confirm which fabric article and finish the color is for. A smooth legging fabric and a brushed fabric can look different in the same shade because their surfaces reflect light differently. If a sports bra and leggings use different fabrics, ask for a lab dip on each material and tell the supplier the pieces will be sold as a set.

How to Review and Approve Lab Dips

1. Compare the samples under agreed lighting. Review the swatches against the original target under a controlled daylight source, then check them under a second light relevant to where the product will be sold or worn. A match under one light can shift under another. This is called metamerism.

2. Lay matching components side by side. Keep the face and direction of the fabric consistent. Include any visible elastic, binding or lining that needs to match. On a textured or shiny fabric, look from more than one angle before deciding the shade itself is off.

3. Give feedback the mill can act on. Instead of saying “the green looks wrong,” try: “Use option B as the starting point. Reduce the yellow cast without making the shade darker.” Record the fabric code, color reference and approved option so both teams work from the same sample.

If your brand uses a numerical color tolerance, agree on the measurement method and the acceptance limit before reviewing submissions. A color-difference value is useful only when both teams know how it was measured and what it is being compared against.

Check Bulk Shade Before Cutting

An approved lab dip is the reference for bulk dyeing, not approval of every production roll. Ask for representative swatches identified by dye lot and compare them with the approved reference under the same lighting. If one color is split across multiple lots, compare those lots with one another as well.

For garments with several visible panels, agree on how the cutting team will group rolls by shade. A small difference that is hard to see on separate swatches can become obvious when two panels are sewn next to each other. For matching sets, review the finished fabrics together again before releasing them for cutting.

Color matching and color fastness are separate checks. A shade can match the reference and still need testing for color change or transfer during washing, rubbing or perspiration. For more on those tests, see our fabric color fastness guide.

Request a Lab Dip for Your Project

Developing a custom color for leggings, sports bras or training tops? Contact Hongjun Fabric with your fabric reference, target color, intended finish and a list of the components that need to match. Flagging matching sets at the start gives the mill and garment team a chance to review the colors together before bulk production.