Thanks for the explanation and the image. This is not a patch on your effort but the same basic issue on a far smaller scale. I once modeled a full Pullman-Standard, streamliner era, diner kitchen (acres of stainless steel) and put in a "sink" visible through one of the windows. The resin was slightly tinted green to resemble dishwater . . . I had to seal the thing inside and out with a coating of acrylic modeling compound because otherwise the Magic Water seeped through any even slight opening and made a mess of the kitchen floor! As I had not mastered how to create "suds" it was less realistic than I hoped but there is a Vallejo paint that will produce the effect.
Wow! Look at that!!