Hydrochloric Acid
Hydrochloric Acid Acid is used to etch newly laid cementitious before painting.
It is also available to remove unwanted mortar splashes from bricks.
Hydrochloric acid and can also be applied 
as a rust remover.
See Phosphoric Acid.
It is inportantant that the all H&S and Product details are followed as stated on the manufactures data sheets before use.
Impervious
A paint system or surface which restricts the passage of moisture or moisture vapour through the paint film or surface
Institute of Corrosion (icorr)
The 'Institute of Corrosion' membership, is recognised as being the lead training body for those interested in becoming a Paint Inspector being one who monitors the application of Paint/Coating systems in the prevention of metal corrosion.
Spray gun nozzle which combines air and fluid before leaving gun. 
Intumescent
Flame or fire resistant coatings which increase in volume on heating.
https://www.youtube.com/watch?v=_Rh4C3FpJ8o