It's a 1,000 sqft, 50-year-old greenhouse. I am replacing the missing and broken annealed glass. Each aluminum brace/upright has a gap for caulking. It appears they used some kind of rope caulk (which I can't find in stores).

QUESTION: What kind of caulk should I use in the aluminum braces as I layer caulk, the glass, and the aluminum holding strap?

I really would be interested in an answer to this question about rope, caulking for my greenhouse, as I am assembling my 30 year old greenhouse as well?

Are you sure that material you're holding isn't an extruded vinyl glazing bead that has been seriously degraded by UV light?

Before I retired and sold my business, I owned a glazing contracting corp. For a project like you're describing, we would prep the aluminum surface with rubbing or denatured alcohol and use a single component polyurethane sealant - Vulkem, e.g..

Al

Hey y'all. I found what works well. M-D Building Products 90 ft. Gray Replaceable Caulk Cord Weatherseal for Small Gaps & Cracks. Pulling two or three strands at a time allowed for a pliable solution. The greenhouse is all closed in with replacement windows and plants that the squirrels and raccoons can't get at.