Before application of Metal Clean Britte, we have to understand its cleaning principal...

In general terms and thumb rule for Metals Britte is MORE RUST required more Metals Britte. Chemically Rust { iron oxide (FeO) } is soluble in pH values below 4.0, . Thus, the oxide (oxygen) dissolves as it is formed instead of depositing on the metal's surface. So it is clear more rust required more Metal clean Britte to get dissolve. In practical if the area is fully rusted corroded then direct Metal Clean Britte can be used to dissolve rust particles, while in light contaminated part Metals Clean Britte can be diluted in between 20 to 70% .

HINTS : MORE RUST required MORE METAL CLEAN RUST DISSOLVING SOLUTION, So before uses try to remove loose RUST PARTICLE, This trick will save lot of CHEMICAL USE.

2nd factor is the time which is directly affecting the cleaning result. If base metal is Aluminium then use Metals Clean Britte concentration 10 to 30% for not more then 5 Minutes. For removal of rust stains on painted or iron surfaces, use 10-30%  of Metals Clean Britte soultion for 15-20 minutes. And for heavily rusted and corroded or soiled surfaces and tarnish on copper and brass, use a solution of 20-50%, for 15-40 minutes.

The 3rd important point always be noted, After cleaning of rust from Metals clean Britte all area should be fully rinsed and clean properly with fresh water. And for best long time result to keep rust free surface, Surface can be chemically neutralized with RXSOL-41-8896-025 ( dilution ration 1 Ltr RXSOL-41-8896-025 with 10 Ltr water ). The scientific reason behind that is  As With the Rust oxide gone with Metals Clean Britte, the metal surface is in direct contact with the acidic solution, and the corrosion reaction proceeds at a greater rate than it does at higher pH values. For increasing pH values greater than pH 10, the rusting rate seems to fall as pH is increased with help of RXSOL-41-8896-025.(http://www.rxmarine.com/Professional-Heavy-Duty-Alkaline-Cleaner)