Maybe Amazon doesn`t have the starter kit. but I buy the 4oz cans in a 6 pack from a POR 15 distributor in Sacramento. these people are usually at a Hot Rod car show I go to, and I pick it up there.
The paint will keep in the can if it has not been opened.
Once opened, then make sure the grove is clean, place a piece of Seran wrap across the opening, then replace the lit. (Hammer it on).
turn the can upside down, this will insure air doesn`t get in.
The paint is cured by the moisture in the air. It is recommended to dip out the paint you need, and then seal up the can. by painting from the can, then the moisture in the air is starting the chemical process in the open can.
I have cans where the paint is cured inside the can after I placed the Seran wrap under the lid. but I left the cans upright. the can will bulge from the curing process.
If you live in an arrid region like Arizona, the paint will almost never dry. spray some water around the area, and it will speed up the curing.
I learned some of these tips from the POR Distributor.
http://www.por15.com/Data%20Sheets/POR15ApplicationInfo.pdf
It is a great product if used and designed.
Charlie