Now this is just our opinion, but different companies utilize different equipment and methods to transport the materials and equipment to their job sites. Most sealcoating companies use cylinder tanks that are towed on trailer units that are pulled behind a pickup truck or attached to a flatbed truck. Those tanks come in various sizes like 300 / 500 / 1000 / etc. gallons. These cylinder tanks have paddles inside of the tanks that can be agitated either by hand or mechanically. This is very important because agitating the sealcoat material keeps it blended or mixed properly. The top performing sealers will have sand, polymers and a percentage of water in the mix design of the sealer to make it durable and long lasting. If these sealers are not agitated regularly the sand falls to the bottom of the tank as well as the polymers.
So if a contractor shows up with a bunch of 5 gallon buckets, most likely bought from a big box store (which is not recommended) or a square plastic tank with sealer in it, ask yourself the following, how are they getting the heavy materials like sand and the polymers mixed properly? The answer is they are not and you are getting an inferior product. It will look good for a few months if you are lucky and it will not perform the way it is supposed to and when you try and get them to address this, you realize that they are long gone with your hard earned money. Now you have to pay to get someone to come redo your driveway or parking lot costing you even more money. So when you are getting estimates from contractors ask them what do they use to transport and apply their sealer. It could save you hundreds if not thousands of dollars.
Not all sealers have sand and polymers but like stated above the top performing sealers do and the top sealcoating companies use these.