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Why does nobody talk about the risk of using old chalk lines on a hot roof?
I was re-sheathing a garage roof in Tacoma last summer, temperature hit about 95. Snapped my chalk line for the first sheet of plywood, but the line was faint and old. I didn't think much of it and cut. When we went to set it, the sheet was off by a full inch over the 8-foot span because the chalk had basically dusted away in the heat. We had to pull all the nails, re-snap with a fresh line from the truck, and re-cut. Ever since then I keep a new chalk box in my roof bag from May to September. Does anyone else switch out their chalk seasonally, or am I just being overly careful?
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richard_dixon1mo ago
Totally agree with @lily_singh2 about testing it first. Old chalk just turns to powder in the heat... learned that the hard way too. Now I keep two boxes in the truck just in case.
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lily_singh21mo ago
Spot on about the heat killing old chalk, but it's not just about swapping boxes seasonally. The real trick is to snap a test line on some scrap before you commit to the cut. I've seen fresh chalk from a new box be junk right out of the bag. If it doesn't pop bright and clear on a hot surface, it's useless. So I check every time I refill, not just when the seasons change.
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