This product is powdered chalk formulated specifically for use with the CL30 chalk line reel. It provides the fine, even dust required to load into a line reel so that snapping the cord produces a clear, straight marking line on timber, masonry and other common building materials. The primary use is for laying out straight guide lines in carpentry, brickwork, plastering and general site marking where a temporary, visible reference is required.

The chalk is a fine-grade calcium carbonate (builder’s chalk) with a free‑flowing, low‑dust finish that coats line cords evenly to deliver crisp snap marks. It is supplied as a dry powder; thread type, head type and drive type are not applicable to this product. The material is manufactured under quality management to ISO 9001:2015 and complies with EU REACH chemical safety requirements for general industrial use.

Typical applications include layout and alignment in joinery and shopfitting, marking courses for bricklayers, setting out tiling and flooring, and general workshop or site use by decorators, roofers and landscapers. Metalworkers and utilities teams also use chalk lines for rough alignment where a removable, non‑permanent mark is needed. For best results use on clean, dry surfaces; contrast colour options such as white, red or blue are selected to maximise visibility on different materials.

Key benefits include good adhesion to line cords for consistent marking without clogging the reel mechanism, non‑abrasive powder that will not damage cord fibres or plastic components, and compatibility with CL30 and most standard chalkline reels. The powder is non‑staining to most finishes and easy to remove with a brush or damp cloth. While suitable for outdoor use in dry conditions, marks may fade in heavy rain and should be considered temporary.

Duchy Fasteners stocks this CL30 refill chalk in trade sizes to suit small workshops and site crews; we offer refill tubs and multi‑packs in a range of colours and weights. Contact Duchy Fasteners for current pack sizes and availability.