Insulative paint is commonly thought to be paint containing ceramic micro-spheres that have the same heat reflective properties as the tiles on the space shuttle. This is a misconception that has come about due to marketing by paint manufacturers. The Space Shuttle does not use ceramic microspheres as insulation but instead uses a proprietary ceramic based material that has the feel and weight of typical styrofoam.
Ceramic microspheres were developed by [3M- reference: http://www.compositesworld.com/articles/microspheres-fillers-filled-with-possibilities) and are used as lightweight fillers for plastics, putties, as well as in paint. Many micro-spheres are hollow and some are solid. Hollow microspheres may be filled with inert gas or a vacuum however when used in paint they do not have nearly enough mass to act as miniature thermos bottles as is the commonly advertised claim.
The areas of the space shuttle that have the highest heat loading due to friction upon the shuttle's re-entry with the earths atmosphere are coated with a black carbon material (reference: http://depts.washington.edu/matseed/mse_resources/Webpage/Space%20Shuttle%20Tiles/Space%20Shuttle%20Tiles.htm) which reflects over 90% of the friction induced heat that the shuttle experiences upon rentry. A true "Insulative" or "Insulating paint" uses a parallel technology where a broad spectrum thermally reflective coating is applied to a specific type of micro-spheres to block heat radiation in a much larger or broader range of thermal energy (heat)to dissipate heat rapidly.( reference: http://www.sti.nasa.gov/tto/Spinoff2007/ch_4.html ) This type of coated thermally reflective material (coated micro-sphere) reduces heat transfer through the coating with 90% of solar infrared radiation and 85% of ultraviolet radiation being radiated back from the coated surface. A true "Insulative" or "Insulating" paint works bi-directionally (reflects heat coming from either direction toward the painted surface. An example of this would be an exterior wall of a building to which an "Insulative" or "Insulating" paint has been applied. Solar induced heat (direct sunlight) is reflected from the surface as well as heat (winter months) that is migrating through the wall outward toward the colder outside air. A "thermal Image" or infra-red photograph will clearly show the reduction of winter time heat loss from a home through areas that have been painted with a true "Insulative" or "Insulating" paint. (reference: http://www.insuladd.com/product-info/seeitwork.html or http://www.thermakote.com) The ability to reflect or block heat from all sources such as fireplaces, heaters, and radiators inside a building as well as sunlight is the value of a true "Insulative" or "Insulating" paint. (reference: http://www.nasa.gov/topics/nasalife/green_paint.html) These products reduce the work (heat loading) that "resistance insulation" such a fiberglass, foam, and rock wool have to do. These are typical insulation materials used in walls as well as ceilings of buildings.