190sl Undercarriage paint
Preparing the undercarriage to accept its first coats of paint was made easy with the body rolled to its side. The entire undercarriage was acid washed with POR15 Metal Ready in a plastic spray bottle after cleaning with panel wipe. The spray allowed the acid to be sprayed deep into the joints. Several coats were applied with a hard brush and 3m Scotch Brite pad until all signs of surface rust were removed. The acid was continually sprayed with water from a plastic spray bottle to keep the acid from drying and to reactivate it. After soaking in acid for 20 minutes the floor was thoroughly washed down with warm water and immediately dried before any rust formed.
The dry floor was then sanded with 3m Scotch brite pad and cleaned with panel wipe and degreaser. I used a Devilbiss GTI gravity feed gun with a 1.4mm tip to spray the floors with three coats of PPG DP40 epoxy primer. This should provide sufficient coats to seal the metal over which was sprayed 3M smooth anti chip coating, Grey part number: 08886. I like this product as it is smooth and overpaintable and sharing the same, robust anti-chip benefits of the textured product, 3M™ Smooth Coating dries rapidly to an excellent finish. Applied using the pressure adjustable air-fed 3M Pressure Pot Stonechip Applicator gun gives the best results.
The joints were seam sealed with Wurth Polyurethane adhesive and sealing compound. Product 0890 100 2 Grey using a hand application gun. A further coat of PPG DP40 epoxy primer will follow three coats of PPG's DAR 4065 "Sandalwood" Semi-Gloss tan/grey.
Ensure that before any original floor pans are removed that you mark the locations of the brake and fuel pipe clamps and ensure these are drilled before painting. If using original mounting clamps ensure that square holes are drilled and pre-fit the pipes, clamps, fuel tank and fuel filter to ensure location is correct. This was aided as the body was rolled onto its side. Additionally before painting ensure that the two holes for the rubber exhaust bumper are drilled in the right hand front floor pan. The fronts of the floor pan that meet the lower firewall panel were originally factory bent at a ninety degree angle and upwards. This will cause an obvious water trap. I decided to seam weld at this joint and cut of the lip by grinding back. Push plenty of seam sealer at this point, when I say push do not use a brush, instead use a putty knife to ensure it is as tight as can be.