Now this is in NO WAY an endorsement of the liquid head gasket sealing methods... no, this is just my own experience on the *ONE* time I have tried it.
Twenty or so years ago I was travelling Northbound on Hwy167 in WA State in my '88 Taurus. Came around a left hand bend and dropped down into the valley, just cruising along in the right lane on my way to my non-descript second shift job.
After getting a couple miles into the valley I noticed that no one seemed to be passing me in the left lane... an unusual thing when driving in the right lane along that straight stretch road. Having not even bothered to check my mirrors in quite some time, I glanced back and quickly discovered why no one had passed me. In fact, no one was even close to me, as all I could see was a thick cloud of white smoke behind me!
I pulled off onto the shoulder the and eventually noticed cars tentatively coming through the cloud, cautiously and with all lights on. lol Once breaking through barrier... and seeing the Spy Hunter style smoke screen emitting car stopped on the shoulder... they all accelerated quickly to get by me!. While sitting on the side of the road I noticed that at lower RPM's it was not nearly as bad coming out the tail pipe, so I limped it to the next exit and took side roads the rest of the way to work. I got home without much trouble since the drive home was during the early morning hours.
Anyway, speaking to a friend of mine, old-timer formerly non-professional mechanic, he mention Liquid Glass and told me that I could find it at any non-national chain pharmacy. So that weekend and skeptical at best, I walked in to a small town family owned pharmacy and asked the back counter about this "Liquid Glass" stuff. The lady had no idea what I was talking about, but called the pharmacist from the back to question him. He walked me out to an isle right away and asked if I new what it really was. Not knowing he told me that it was an egg preserver, and then asked if I intended to use it to seal a head gasket leak... which I had no stated prior. An old mechanics trick he said, and one he'd done a few times over the years, he was probably in his late 50's to early 60's. After a fairly long discussion about it he reasonably dispelled my doubts, or at least enough to for me to give it a try.
Per his direction, I poured 1 cup into the radiator and drove the car for 20min after it had fully warmed up. He said that if it did not work, then let it cool and add 1/2-1 cup more, but no more he stressed and repeat the drive. But for me it did not get to that, as the first cup and the 20min drive completely sealed up the leak. I drove the car without any further problems for another few years before selling it.
Again, this is not an endorsement, as I have only ever tried it that one time, so I do not have enough experience with it to recommend.