IRWIN STRAIT-LINE Permanent Chalk Indigo Blue 4 lb | 4935524

Reliable outdoor marking with vivid Indigo Blue chalk

IRWIN STRAIT-LINE Permanent Chalk in Indigo Blue is designed to perform under real-world jobsite conditions. The 4 lb bottle is easy to grip, and the crisper lines it leaves help crews measure, mark, and proceed with confidence on concrete, wood, dirt, and metal surfaces. The color choice provides strong contrast on most backgrounds, helping once-sketched lines stay visible as work progresses.

Why this chalk stands up to the job

• Extreme outdoor resilience: its formula holds up to sun, wind, rain, and temperature swings, preserving legibility for hours or days between applications
• Large 4 lb supply: fewer replacements mean less downtime and more time on the job
• Indigo blue color: high visibility against common substrates used in construction and landscaping

Smart design that keeps you in control

• Flip-cap keeps the chalk inside the bottle, reducing spills in pockets, tool belts, and wind gusts
• Flip-top cap forms an airtight chamber that blocks moisture and minimizes clumping, helping chalk flow smoothly
• Rugged bottle shape fits standard line-marking tools and makes reloading quick on busy sites

Practical field tips

For crisp, straight layouts, use with traditional chalk lines or line markers. To maximize performance, keep the cap closed when not in use, store upright away from moisture, and re-check marks after weather changes to confirm visibility.