Black Ox Sealant is a new bike tire sealant designed to work for mountain, road and gravel bikes (even in inner tubes for basically any bike). Its secret sauce is a mix of different length carbon fibers blended into the latex-based sealant.
And those fibers are chopped in house to control the lengths, then blended with other materials to create a sealant that uses both physical and chemical properties to plug holes up to 9mm in diameter. To test it, they shot the spinning tire with a rifle:
They also tested it with three different screwdrivers puncturing the tire, ripped out at once, with surprisingly little air pressure lost:
It’s made in Oxford, North Carolina, using technologies and materials borrowed from their parent company, which makes products for the aerospace industry. It’s good down to 20ºF (-6ºC), with a cold-weather formula planned for later this year. They say it’s compatible with other brand sealants and Cush Core inserts.
Retail is $5.99 for a 4oz bottle, $17.99 for 16oz, and $28.99 for 32oz. They recommend about 2oz for a 700×40 gravel tire, moving all the way up to about 10oz for a 29×3.8″ tire. So, probably best to get the bigger bottles.