Hi Susan.
Augusto is correct. It is exactly the same ingredient used in the stiffening of collars, creases, etc. There is a powdered form which must be mixed with water. Another form is the spray. Then, there is the liquid which is marketed in a plastic jug.
Now, the tissue:
Craft tissue is sometimes referred to as silk tissue or gift tissue. It is not the nose tissue or toilet tissue variety. It is marketed in large sheets, small squares and circles and sometimes shredded. Most popularly used in gift bags to add color and protect delicate objects. They are used in the making of flowers and pinatas, as well.
Florists also use a similar type of tissue paper which has a waxed coating. This is used to wrap around fresh flower stems and available through wholesale florist suppliers. The craft related tissues are quite colorful and are packaged as either Bleed or Bleed Resistant. School suppliers usually carry the squares and circles.
Hope this helps.
Rozani