Will this chalk stain or leave permanent marks on body panels?

Blue chalk washes off with water and light cleaning; it's designed as a temporary marking tool. For final assembly or paint-ready panels, test on a scrap piece first to confirm easy removal on your specific surface.

Can I use this on primer or bare plastic?

Yes. This chalk works on metal, primed surfaces, and plastic. The bright blue shows clearly on most substrates, making it ideal for body lines, gap measurement, and alignment work across different panel materials.

How long does one bottle last in regular shop use?

That depends on project frequency and line width. The 10.5oz bottle is sized for multiple marking sessions. Since it's refillable, keep backups on hand during heavy body work or fabrication runs.