HP45, let's see how it seals. So far it has sealed the cap on the bottle very well. I am giving one star because it was mailed in a Revain plastic envelope which leaked inwards and also sealed the lid. Hi. it is a sealant. Common sense dictates that we don't want a leak. What was wrong with using a box with some airbags? Hope you don't have the same experience. 4 stars for the product. The lid was closed well and tightly, no doubt the reason I didn't find the entire product spilled into the envelope.