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Where the optimizations come from is in figuring the ratios of metal to sensitizer needed to balance the process equations. It can be demonstrated (see studies) that too little chemistry will adversely affect print quality and too much chemistry will go unused and be wasted. Also there is much better consistency of performance when interchanging solutions if those solutions are optimized.
Optimized Formulas
for Metal SolutionsCalculators
Table - DOP 27%FO
Table - POP 35%AFOTo accomplish this balancing, the molar concentration of the sensitizer solution is calculated from the percent value of the solution and the molar mass (formula weight) of the material. With the mass being conserved, using the process equation ratio, the molar mass is calculated for the metal double salt (MDS). From the molar mass of the MDS is calculated the molar concentration, and then the percent of the MDS solution. (For an explanation of molar concentration and percent see Making a Percent Solution.)
The ratios for the process equations have been empirically verified to be 1:1.
The optimum solutions for the metal double salts (MDS) are calculated from the equation:
(% MDS solution)=(fw MDS)/(fw sensitizer)*(ratio)*(% sensitizer solution)For the palladium (Pd) double salts, each molar equivalent of Pd MDS is mixed from one molar equivalent of PdCl2 and two molar equivalents of the appropriate alkali-chloride salt (salt). The solution concentrations of PdCl2 and whichever salt are calculated as follows.where,
fw = formula weight or molar mass
ratio = (molar mass MDS)/(molar mass sensitizer) from the process equationNOTE: The molar mass for various chemicals are listed in the section, Formulae.
(% PdCl2 solution) = 1*(fw PdCl2)/(fw sensitizer)*(ratio)*(% sensitizer solution)Ferric Oxalate (FO) has been traditionally mixed to a solution concentration of about 27%. The metal solutions are calculated for this value. A weaker solution might result in a noticeably weaker print, however this is dependent on the paper, coating efficiency, and technique.(% salt solution) = 2*(fw salt)/(fw sensitizer)*(ratio)*(% sensitizer solution)
Higher concentrations of FO may be mixed with the addition of EDTA to the solution as has been suggested by John Melanson and Richard Sullivan. FO solutions as high as 32% have been made with the addition of 4% EDTA(Na4). However, the higher concentrations along with the appropriate metal solutions do not provide for any further improvement in the print; as the threshold has been passed. The Threshold for DOP Solutions Study can determine the concentration at which point prints show no improvements.
A further consideration is the purity of FO powder. Adjustments should be made to reflect the accurate amount of FO involved. The FO Sensitizer Formula Calculator considers the purity of various FO powders based on studies identified in section, Formulas for FO Sensitizer Solutions.
Ammonium Ferric Oxalate (AFO) can readily be mixed to higher solution strengths (60%) but a threshold is also encountered of the maximum amount of metal that can be placed into the coating such that any additional amount will not result in a noticed benefit to the print. This threshold is also a function of the paper, coating efficiency, and technique. For the Crane's Parchment Business Card Stock (AKA: Cover-90 or CP) this threshold has been found to be the amount produced with a coating mixture based on a 35% solution of AFO as determined by the study Verification of Optimized Formulas (Threshold for POP solutions).
Some of the metal solutions will not stay dissolved at typical laboratory temperature and pressure, so heating of the solutions may be required. For these, an optional half strength solution (which does not require heating) is also described (intended to be used with the double Quasi Muti-Coating Method.)
Note: Instructions for mixing are included in the section Preparing the Stock Solutions.
Note: Be sure to label all solution bottles with the % concentration as well as the name
of the solution.
To determine the Sensitizer Solution Formula use the Calculator FO Sensitizer Formula Calculator (requires JavaScript capable browser) To determine the Metal Solution Formula use the Calculator (recommended)
or one of the Tables below.Metal Solution Formula Calculator (requires JavaScript capable browser) TABLES: Please note that the tables will no longer be supported or updated. Optimized Formulas for DOP - using Ferric Oxalate sensitizer Using a 27% solution of Ferric Oxalate to make 60 ml Optimized Formulas for POP - using Ammonium Ferric Oxalate sensitizer Using a 35% solution of Ammonium Ferric Oxalate to make 60 ml Top of Page
Optimized Formulas for DOP - using Ferric Oxalate sensitizer
Using a 27% solution of Ferric Oxalate.
These are the trditional recommended solutions for DOP use with any paper.
With a sensitizer solution of 27% Ferric Oxalate, the solutions for the MDS are:
MDS strength half strength K2PtCl4 23.2% 11.5% Li2PdCl4 14.6% Na2PdCl4 16.4% K2PdCl4 18.2% 9.11% The calculated formulas for the MDS solutions are as follows with the 100ml H2O indicating to add H2O to a final volume of 100ml.
Lithium Sodium Potssium Platinum 4.73 g LiCl 6.52 g NaCl 8.32 g KCl 23.16 g K2PtCl4 9.89 g PdCl2 9.89 g PdCl2 9.89 g PdCl2 100 ml H2O 100 ml H2O 100 ml H2O 100 ml H2O
The recommended metal solution formulas for use with a 27% solution of Ferric Oxalate to fit in a 2 ounce bottle (60ml) are as follows with the 60ml H2O indicating to add H2O to a final volume of 60ml.
Note: "must be heated" indicates that this solution must be heated in a hot water bath to dissolve all material prior to each coating mixing operation. Do not heat the platinum solution above 140oF. For these solutions a half strength formula (which does not require heating) is given to be used with the double Quasi Muti-Coating Method.
Lithium Sodium Potssium Platinum 2.84 g LiCl 3.91 g NaCl 5.00 g KCl 13.90 g K2PtCl4 5.93 g PdCl2 5.93 g PdCl2 5.93 g PdCl2 60 ml H2O 60 ml H2O 60 ml H2O 60 ml H2O ^ must be heated ^ ^ must be heated ^ v half strength v v half strength v 2.50 g KCl 6.95 g K2PtCl4 2.97 g PdCl2 60 ml H2O 60 ml H2O
Optimized Formulas for POP - using Ammonium Ferric Oxalate sensitizer
Optimized Formulas for a 35% solution of Ammonium Ferric Oxalate.These are the recommended solutions for POP use with CP paper.
With a sensitizer solution of 35% Ammonium Ferric Oxalate, the solutions for the MDS are as follows:
MDS strength half strength K2PtCl4 33.9% 17.0% Li2PdCl4 21.4% Na2PdCl4 24.1% 12.0% K2PdCl4 26.7% 13.35%
The calculated formulas for the MDS solutions are as follows with the 100ml H2O indicating to add H2O to a final volume of 100ml.
Lithium Sodium Potassium Platinum 6.93 g LiCl 9.56 g NaCl 12.19 g KCl 36.88 g K2PtCl4 14.50 g PdCl2 14.50 g PdCl2 14.50 g PdCl2 100 ml H2O 100 ml H2O 100 ml H2O 100 ml H2O
The recommended metal solution formulas for use with a 35% solution of AFO to fit into a 2 ounce bottle are as follows with the 60ml H2O indicating to add H2O to a final volume of 60ml.
Lithium Sodium Potassium Platinum 4.16 g LiCl 5.73 g NaCl 7.31 g KCl 22.13 g K2PtCl4 8.70 g PdCl2 8.70 g PdCl2 8.70 g PdCl2 60 ml H2O 60 ml H2O 60 ml H2O 60 ml H2O ^ must be heated ^ ^ must be heated ^ v half strength v v half strength v 3.66 g KCl 11.07 g K2PtCl4 4.35 g PdCl2 60 ml H2O 60 ml H2O
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