Hi Thieu - good to hear you might tackle FEG soon.Thieu wrote:Because space is so limited where I live now, peaceful coexistence of holographic plates and dinner plates is the only option in the kitchen at the moment so dichromate is a bad idea. That's why I'm particularly interested in FEG again. The last thing I remember is you were using ferric ammonium oxalate and developed with H2O2, is that where you both settled on or did you explore other salts/processing after that?
It remains to be seen if the ferric salts show similar levels of light sensitivity as the dichromates at 445nm (in some cases speed at 405nm was considerably higher for FEG than DCG).
The specific salts I did try successfully, were ferric ammonium citrate (FAC), ferric ammonium oxalate (FAO) and ferric oxalate. FAO proved to produce the best results. I'm not sure if FAO could be considered a "kitchen chemical" (though definitely better than the dichromates).
To this date at least two issues remain ambiguous
1) the choice of gelatin. We never systematically tested what kind of gelatin performed best etc. As of now a simple (swine) food gelatin, produced by Gelita, has become kind of a standard.
2) layer thickness may be another important thing to consider. Thin layers seem to do nicely, whereas thicker layers become prone to uneven development.