PVA and Adhesive Electroplating Issues

? What is your photoresist? Many resists are quite capable of taking the pH of Woods nickel.

A. Try polyvinyl alcohol that is crosslinked by exposure to UV light using sodium dichromate as the promoter. It is a well tried system that has been around for many years.

A. PVA resists are hydrophillic and I would not expect them to stand up to aggressive plating solutions; not to mention the possibility of dichromate contamination of the nickel tank. This is one of the reasons they were obsolete in the 1970s.
Modern commercial negative resists are based on rubber (poly cis-isoprene ) or co-polymer (poly-vinyl cinnamate). Either should stand plating. The positive resists based on the Kalle patent are less resistant.
The critical stage of any resist process is the UV exposure and this must be controlled. The best way is by using an optical step wedge (ask your supplier). Alternatively determine the correct exposure by trial. Remember that photo exposures must double each time. 1, 2, 4, 8 minutes, seconds etc depending on your light source. Many operators try to speed up the process by reducing the exposure. The resist is not completely cross linked and is liable to be attacked by the plating bath. Note: if the bath has been attacking the resist, it will probably need a carbon treatment before you can expect good results.

A. There could be many reasons but the ester groups of the PVA glue (polyvinyl acetate) react to alkaline substances producing polyvinyl alcohol and acetic acid [on eBay or Amazon]. Perhaps the clay you are adding is promoting this reaction. On the other hand, it is well known that hard chrome is not very corrosion resistant, specially in acidic humid environments. If the problem proves to be corrosion, a nickel undercoat will help.

A. Hi Marc. I know you said you failed by using PVA glue but I decades ago used Elmers brand very successfully many times. I mixed it with water 50/50 and soaked the fabric overnight in the mixture. Let dry thoroughly over a shaped mandrel and it will be very hard with no lose of detail. I've done this with sand dollars, too, with success.

As stated previously PVA glue did not yield success in the last attempt, I'll follow your recommendation and see if I get better results.
In the interim I did see good results using clear polyurethane finish. Samples remained fairly rigid after 2 hours in the test plating bath.
Water based clear acrylic also yielded poor results, becoming flexible again in the first hour of immersion.

I'll be making some conductive coating for plating things next, either nano-particle copper (ascorbic acid + copper sulphate [on eBay or Amazon] to precipitate very fine copper powder) or graphite.