4.5 gal. UltraLightweight Ready-Mixed Joint Compound

if it is like any product that after a time or the expiration date does not work the same as it is freshly made

Yes

I don't think I would use this for a knockdown texture. My understanding is that one of the ways the manufacturer is able to make it ultra lightweight is that they reduce the amount of "glue" in the product. This does result in a compound that has slightly less adheasive properties. I would use it if I was doing a light ceiling texture, I just would not be comfortable using it with a knockdown. As far as using it on a painted wall, as you may know, paint acts as a sealer on the drywall and can cause the mud to Bubble. So I would either sand and primer the wall or put a very tight skim coat of mud before doing the texturing. Hopefully others have a little more experience and can post a more definite answer. I would be interested to hear what other users have to say. If you use this product for knockdown let us know how it works out! Happy mudding :-)

I'm not sure how to answer your question. This has been the only color of lid I have seen on this product in our area. My understanding is that it's a newer product and for some manufacturers is replacing what they used to call topping. Although, when it comes to the color of the mud, it doesn't seem to dry as white at some of the topping I have used in the past. I hope that is helpful.

4.5

Several possibilities - watered down too much - excessively dry environment/ultra low humidity - substrate movement

It has different uses. The type of mud used depends on what stage of the process your in, i.e. final skim coat. This mud isn't recommended for everything, use all purpose if your looking to use for everything.

Yes

Yes. Use sheetrock tape, go over it with a thin layer of compound, let it dry, then repeat. You need to go wider with each layer and sand until the wall is smooth and you can't see or feel any screws, tape, or other blemishes. It helps to use a light to shine up the wall to spot imperfections.

Yes, but only on the last coat. A hard mud such as 45 minute or 90 minute on the first coat.