Rash Guards and Swim Shirts: UPF, Chlorine and Drying Speed
Rash guards sit between sun protection and compression, so fabric must deliver UPF, chlorine resistance and quick drying together.
This article sets out what the requirement involves, how to specify it and how to verify it before bulk production.
Fabric specification basics
Fine-gauge knits at 180 to 220 GSM with chlorine-resistant elastane give the required stretch and recovery.
It rarely appears on a packaging claim, yet it shapes how the garment feels in the first hour of wear.
Achieving UPF 50
Dense construction, darker colours and polyester-rich blends raise protection without losing comfort.
Record the measurement conditions alongside the target, including conditioning, sample size and number of test specimens.
- Ask for a separate price line for the requirement
- Confirm minimum quantities before committing the colourway
- Build one extra approval round into the calendar
Chlorine and salt exposure
Chlorine degrades standard elastane quickly, so pool-oriented styles need dedicated grades.
Record the machine settings for each approved lot, so a repeat order can be reproduced rather than re-invented.
Seam and print considerations
Flatlock seams sit comfortably under a wetsuit, and sublimation keeps prints durable in water.
Share the results with the mill, since transparency usually shortens the path to a workable solution.
- Confirm the numeric range and the test method in the specification
- Keep an approved physical standard at the machine
- Retest after the agreed care regime before shipping
Testing programme
Combine UPF, chlorinated water fastness, elongation recovery and drying time tests in one approval round.
Review the requirement annually against market prices, as the cost of some materials moves faster than others.
Summary
A clear specification, a trained operator and a documented test together remove most of the risk from this part of the programme.
