Method of masking plated article with a poly(isobutyl methacrylate) and poly(vinyl toluene) containing coating

DETAILED DESCRIPTION OF THE INVENTION My invention will be better understood in terms of the following specific examples.
EXAMPLE I A front side marker for a 1979 Oldsmobile Delta 88, including painted housing and bright chrome trim portions, was molded from a platable grade of ABS resin.
The part was positioned in a paint shield that covered the surface portions of the marker to be plated.
The exposed surface portions were then sprayed with a liquid coating, made up in parts by volume of 9.
6 parts of a stop-off polymer mixture.
The mixture was made up of 60 weight percent poly(isobutyl methacrylate) and 40 weight percent poly(vinyl toluene) resins.
The polymer mixture was dissolved in 90.
4 volume parts of a solvent system made up in volume parts of 62.
5 parts VM&P naphtha, 24.
2 parts mineral spirits, 2.
7 parts aromatic petroleum distillates, 1.
0 parts butyl alcohol, and less than 0.
1 parts silicone fluid for improved coating flow.
The coating had a viscosity of 35-39 inches No.
1 Zahn, a specific gravity of 1.
04, and was approximately 1 mil thick.
The coated part was dried for 10 minutes at 140.
degree.
F.
The dried layer was approximately 0.
3 mils thick, had a Tukon hardness of 11, and a specific gravity of 1.
04.
The gloss of the dried coating, given as a percent reflected light at an incident angle of 60 degrees, was 85%.
The coating itself could be characterized as a clear layer of fused poly(isobutyl methacrylate) and poly(vinyl toluene) resins, strongly adhered to the ABS substrate.
The part was then pretreated for plating with a strongly acidic, oxidizing solution to render the surface hydrophilic.
The surface was neutralized and then treated with a strongly acidic plating activator containing tin and palladium salts.
The part was then subjected to the following plating cycle: caustic soak (pH greater than 11) at 130.
degree.
-150.
degree.
F.
; electrolytic cleaning at 130.
degree.
-150.
degree.
F.
, 12 volts, 1,500 amps; room temperature water rinse; room temperature dip in 0.
2-0.
5% sulphuric acid; acid copper strikes at 70