Here is the excerpt (out of the website citation, above). It is from the Stan’s Sealant guy and from personal experience, I think he is right. Note that when he says Stans Sealant will seal a valve with one drop, all he is saying is that if you use a tube and put some Stans in it, you have to use a tube with a removable core so you can inject the Stans directly into the tube. Also, I think Caffelatex is better in tubes than Stans although I think Stans is better in tubeless applications than Caffelatex – and the Stans guy points out why. Since the Caffelatex foams up, generally there just is not enough liquid to go to a newly opened, larger hole in the tire (like Stans can, since Stans does not foam up but stays in liquid form) whereas in a tube the foamed Caffelatex might actually help more.
“A few things about sealants:
1. Any sealant that will inject through a valve core will seal almost nothing. My sealant will seal a valve core with one drop.
2. Foaming sealants do not work. One of my first sealants was a foaming sealant. I thought it was a great idea but once you take two of three ounces and whip it into foam it leaves no liquid to seal a puncture. I would go on a test ride with my foaming sealant. After a few miles I would stop and puncture my tire. Nothing would come out except air. While removing the tire, I found the inside of the tire was filled with my foam leaving nothing to flow to the puncture. At that time 11 years ago I realized foaming sealants would not give me the performance I wanted.
3. Sealants must be thin to flow quickly to seal a puncture. It they are thick they will never give you good performance.
4. It’s easier to seal tires with no tubes. Tubes stretch making sealing them much harder.
5. NoTubes sealant will seal tubulars better than any sealant I have tested.
6. Sealant that will freeze will not last very long.”
— Stan Koziatek, Stan’s NoTubes