First, at this point and unless you choose to use paper/process specific ICC profiles, you should be using No Color Management. This is important and is stated on page 111 of the Piezography Manual 2017 Deluxe Edition, section D, item 1. This alone could be the cause of your film being reddish and thin.
If I understand your 4th paragraph correctly, you are referring to when the curve is selected, and yes, it can be selected via the “Page Setup: Paper and Printing …” dialog before clicking “Run Print …” or after clicking “Run Print …”, since both open the same dialog. There’s more than one way to skin this cat. But you do need to at least choose the paper size and orientation via Page Setup. Personally I do as much there as possible and save as a preset for each process/paper variation that I use. I think Walker tends to use “Last Used Settings” rather than presets, but he will have to speak to that. There is more than one way to skin this cat. If you set the curve and everything else in Page Setup, it should still be there when you click Run Print.
The illustration is for my 1430. The 3880 has 2 slight differences:
- Paper Feed - you have the option of using Sheet Feed or Manual Rear Feed.
- Black Ink - be sure this is set to Photo if using the standard K7 ink setup. (If you are using a P2 setup with PK in the Yellow position, you would set this to Installed so that it will never initiate a dreaded Black Ink Change.)
You mention that you are using "Na2 Platinum/Palladium". This may be just a terminology thing, but I have to comment since the way you state it could mean a couple of different things and I want to be sure:
- You are using Na2PtCl6 with the standard Palladium solution (Na2PdCl4).
- You are using Na2PtCl6 along with the standard Platinum solution (K2PtCl4) and Palladium solution (Na2PdCl4).
If 1, then how much are you using and of what concentration? You are using it as a restrainer and only need a tiny amount to ensure that the highlights will not fog from less than perfect ferric oxalate. I have tested this extensively and the minimum effective amount of "Na2" is 1 drop of 1.25% per 1.5-2ml of FO+Pd, enough for an 8x10 image size, the range being to account for absorbency of the paper. You certainly can use more but you sacrifice some of the delicate highlight rendering quality that makes the process special. Some printers do without restrainers altogether, which is probably the ideal, but in real life I bet some of them simply have not noticed that their highlights are fogged.
If 2, you will very likely get grungy highlights, especially around the edges and areas of near paper white, because the 2 Pt compounds do not play well together.
Also note that no amount of “Na2” qualifies the resulting print as a Platinum-Palladium print since the amount remaining in the print is infinitesimally little to none. It is a Palladium print. (Sorry, this is a personal pet peeve, and too many printers think that they can get away with it. And yes, I can prove it.)
As for exposure time, that depends more on your light source than anything else - anywhere from 2-20 minutes. If you tell me your time for other processes I might be able to make a good guess. The Na2 makes no difference if you are comparing to other Pt/Pd systems.
Why did you choose to start with the AC Pt/Pd curve? That is one of IJM’s in-house custom curves. You are probably better off starting with the Master curve and creating your own linearized curves from that. Are you using ammonium citrate? If you are not getting nice smooth tones switch to potassium oxalate.