A cotton mattress is cotton. cotton is a plant.
Most foam mattress toppers have a beige or white colored covering. The foam on the inside of the mattress topper may be any color, grey, white, blue etc.
While foam mattresses need not be turned like conventional mattresses, the first word in foam mattress maintenance is the same as it would be for the maintenance of a standard mattress. That word is protection. Covering your foam mattress with a quilted mattress pad cover that is removable and washable will have the biggest impact on preserving both the life and freshness of your foam mattress. Always make certain that the mattress cover is completely dry before replacing it on your foam mattress, and vacuum the foam mattress itself once a month.
which material used in mattress
No
Typically 24 hours is ideal for the foam mattress to regain its natural form.
It is possible that your mattress has a defect. I had a foam mattress cover that seemed to sag in the middle. First I thought it was my bed, but when I removed the foam matteress, the sag disappeared.
An over priced, name brand, (memory) foam mattress.
Yes
It won't do much if you do, but you can try all you want.
There are many memory foam mattress reviews, to be found on the internet. If you do a Google search, you will find plenty of them.
I would personnaly say memory foam is the best (foam) as it is soft, comfortable and takes the shape of your body once you have been lying on it.
There can be a variety of materials including but not limited to: hair, straw, cotton, beads, heavy cloth, foam rubber, springs, or they may be inflatable.