Knife grade is a thick paste that stays where you put it, so it works on vertical seams and mitered edges without running. Flowing grades are thin enough to wick into rodding channels and hairline cracks on their own, which a paste cannot do. Most shops keep both, and some products, including Clarion SF, come in both consistencies under one product name.

Often not. Knife grade epoxy is what the trade calls the format, not the chemistry, and the products sold under that name include polyesters, vinyl esters, methacrylates, and true epoxies. Clarion SF is a vinyl ester. Stone Seam Pro is a methacrylate. Knife grade epoxy, poly-epoxy, seam glue, and seam adhesive all get used for the same shelf, so what matters is which chemistry is in the can and what it is rated for.

Because of shop air. Styrene is a volatile organic compound, the International Agency for Research on Cancer classifies it as a Group 2A probable human carcinogen, and the US National Toxicology Program lists it as reasonably anticipated to be a human carcinogen. Seaming and lamination happen indoors, often in enclosed space, and there are workplace exposure thresholds attached. If you want to know whether the adhesive on your shelf contains styrene, its Safety Data Sheet will tell you.

Tint the resin before you add the hardener, every time. Pull your portion of Part A, add pigment a drop at a time and mix to color, then check it in a thin film on an offcut with a blade before you commit. A pile on the mixing board reads completely differently than the same material squeezed into a hairline joint. Only after the color is right does the hardener go in, because once it does you have a few minutes and no way to correct a miss.

No, and on a tinted seam it will cost you the job. Clarion SF runs at 98 parts resin to 2 parts BPO cream hardener, and Bonstone states that exceeding 2% shortens the pot life and cure time and causes significant discoloration of the adhesive. Discoloration on a color-matched seam undoes the whole reason you tinted it. Mix only what you can spread inside the working window instead.

It depends on the product, so check the data rather than assuming. Clarion SF #5 was tested on Dekton at 698 psi shear under ASTM D905, and some specimens failed at the bond line rather than in the stone, so treat sintered surfaces as a test-first substrate. Stone Seam Pro is rated for porcelain and sintered surfaces. If you are running porcelain slab, call us at (800) 220-1966 before the job and we will tell you what we have seen hold.