From CDags.org Wiki
Gilding is the process of chemically adding a fine layer of gold to a daguerreotype. This enhances the appearance of the image and improves it's durability.
Parts A and B are mixed 1:1 right before use.
In preparing the gold chloride solution add the gold chloride to 400ml of distilled water. Rinse the glass vial or ampoule with distilled water into the solution and top up the solution with more distilled water until it is 500ml. Filter the solution and store in a 500ml amber bottle.
When mixing the A and B solutions, always pour the gold into the sodium thiosulfate solution. The yellowish gold solution will turn clear as this occurs. If you pour the thiosulfate into the gold, a brown precipitate can form in the solution. If the precipitate does form, the solution can be reclaimed by adding a couple teaspoons of table salt to the solution and letting it sit overnight. It is also best if your working strength gilding solution is filtered just before use.
Heat the underside of the plate till the plate steams and continue with care. Small bubbles will form on the plate and darkish clouding may occur which will clear with continued gilding. Most of the gilding will be finished in the first minute or two, continuing for about 4 minutes will help brighten and clear the plate. What hasn't cleared after 4 minutes or so probably won't clear. Stop the heating of the plate and quench it by pouring distilled water onto it. rinse the plate throughly and dry.