You don't really need it...FWIW, It may go on easy, but it will not come off easy--it can also be used to seal gutters and asphalt... Sealants that adhere tightly to trees are not a good thing, because at some point, you are going to have to take it off. It can't remain on bonsai indefinitely because it is noticeable and distracting.
Having had to remove this kind of sealant from stock trees, I can say it is a nightmare to get off.