Does polyurethane make wood waterproof?
I thought I had already answered this question a while ago.The answer is no, polyurethane does not make wood waterproof even if you coat all sides and ends with multiple coats… at least not for very long. Wood expands and contracts and naturally contains moisture even when kiln dried. As it moves it eventually compromises the finish and allow wetness to invade. Thats why at best it’ll only ever be water resistant for a bit of time.This is not meant to insult you, but most times when a person asks about “polyurethane” in particular they are perusing the shelves of a department store or home center and notices the familiar name on the label. That is not the way to choose a protective finish.If you want a longer lasting finish you won’t be able to (successfully) apply it yourself. You will have to use catalyzed urethane (not polyurethane) combined with flawless preparation. Um, you could also coat all the surfaces (remember, top, bottom, edges, and ends) with a catalyzed epoxy finish but that also takes a significant amount of work. Epoxy is likely as tough and waterproof a finish as you’ll get… when applied correctly.
For how long can dairy products be safely left out of the fridge?
It depends on the dairy product. Milk for instance if it was in a retail setting would have to be disposed of if they were using time as a public health control after 4 hours. (This law will be changing in different areas). Certain dairy product need to be refrigerated but are not considered to rapidly produce disease causing organisms, yogurt needs to refrigerated but if it bumps up on the temp slightly it has enough competing good organism that their shouldn't be a concern. Cheeses are going to depend on what they are made from. If they are made from raw milk cheese it has been shown that the 60 day rule may not be long enough to kill all pathogenic organisms so this is a riskier product to leave out, even riskier if it is opened. Good rule of thumb if it is unopened and pasteurized you are for the most part going to be ok to put it back in the fridge but what you need to know is what temp it got up to and for how long. If you had a gallon of milk unopened but out for 2 hours and it's at 80 degrees, sorry milk isn't expensive enough for me to take a chance plus the quality has probably degraded significantly.Opened dairy products in a home setting I wouldn't leave out longer than 2 hours. In a retail food setting they have up to 4 hours at which time they have to dispose of the items. Butter although it can support bacterial growth I wouldn't have a great concern over it unless you are adding things to it such as garlic etc. Clarified butter isn't an issue however and margarine isn't dairy it's plastic.The main thing one should be asking is how quickly can I get my products in the fridge. We need to stop looking at ways to reduce the amount of refrigeration, get a cooler and an ice-pack if needed. It isn't just the possibility that the product you have may have come to you contaminated, it is also the possibility that you have contaminated it yourself.