what is shellac and how does it work?
|various shellac forms scraped and collected from the bark of trees|
I told him it was zinsser spray which contains the strong smelling but distinctive "shellac"additive.
Which you may or may not know is made from beatles wings? or so i thought!
Well its actually a secretion from a beatle called the Kerria lacca which consumes the sap from trees which it then secretes onto the bark, this resulting secretion hardens and is the collected by scraping from the branches.
It is the used in varnishes paints etc and is a constituent part of most stain blocking formulations, it also has that distinctive smell.
Zinsser products have this covers up product which is especially made to spray upwards onto ceilings without tipping the can, the clever nozzle it uses requires the user to simply press the plastic nozzle aside to produce a nice controlled upwards spray onto the offending stain, it does take a little while to dry but forms a very effective barrier to the unsightly stain.
My tip would be to apply it well in advance of over painting to prevent any hold ups.
|Zinsser covers up stain block|
|The clever upwards spraying nozzle