Better Paint Mix and Second Coat on the RH Upper Wing

When I mixed a new batch of light green, I realized I had made some mistake with my spreadsheet for calculating the pigments.  It was causing the quantities of pigments to be so low the paint was watery.  I had seen this with the red, blue and black, but it was much worse with the green.  I spent the morning re-measuring all my pigments by weight and volume to determine their density.  I needed this to correctly convert my weight (gm) measurements into volume (ml) measurements so I could use measuring scoops.

When I first mixed the colors I had access to a very accurate scale.  All I have now is a small kitchen scale which is not accurate enough to measure such small quantities.  Most of the pigments come in 175 ml jars so I have large enough quantities to work out the density with the kitchen scale.
The densities are:
Lamp Black                     0.17 gm/ml
Aluminum Powder           0.27
Prussian Blue                  0.55
Alizarine Crimson            0.66
Litopone                         0.83
Burnt Sienna                   0.87
Chrome Yellow                0.87
Chrome Orange               1.18

 When I mixed the colors I used about 4 times as much pigment as my attempt with the Light Green, which was what I found with the black.  The colors still match and the paint covers much better.
The color mixes here are for Light Green, Beige, Red and blue.  Each has about 25 ml of pigment for a quart of Poly-Tone.  The Alizarine did not want to mix well with the Poly-Tone but the color seems to match my old samples.

 We had another warm dry afternoon so I started the numbers on the lower left wing, and did the red and blue on the roundels.

The upper right wing got a second coat on all the colors.  The red and yellow need another coat and then I can outline the numbers.

After 26 years it's nice to see this paint job getting close to being done.  I really like the look.

Colors on Wings

 The afternoons yesterday and today were both nice and dry for painting.  Yesterday I got the second coat of all the colors on the top of the lower wings.

I also got started on the red in the roundels.  The green stripes are squadron stripes for the 103rd Areo Squadron.  They still need red stripes between the green.

 In the evening when it was too damp to paint to paint I drew all the color boundaries on the top of the upper wings.

Today I was able to get the first coat on the top of both wings.  When the colors are done I'll add a black border around the numbers.

 The upper right wing gets the same green and red stripes as the lower left.

I got the numbers drawn on the lower right in the evening today, but it was too damp to paint them.  Odds are I won't get to do any more painting until mid September.

I did get the gasket set for the engine so I can pull the cylinders to check for rust.  I've only got about 125 hours since the overhaul so I don't want to risk damaging the engine.

Painting the Camouflage Colors on the Wings

 The weather has dried out for a couple days so I finally got some color on the top of the wings.  I bought 4 gallons of the clear Poly-Tone base so I can mix my own colors.  I also bought a quart of Blush Retarder to slow the drying and help with mixing the pigments.  Austin at Preferred Air Parts was very helpful.
I found a plastic lid, at the hardware store, for the gallon can which has a small poor spout.  It allows me to easily poor small amounts of the base without making a mess.

 Based on my color formulas I measure the pigments into my mortar.  This mix is for making 1 quart of the dark brown, Chestnut, color.  It uses Lamp Black, Chrome Orange, Chrome Yellow, Burnt Sienna, and Alizarine Red.

 When I did this with dope I used one of the plasticizers for mixing the pigment.  With Poly-Tone I used some blush retarder, 4 teaspoons for a quart of Poly-Tone.  It gave me a liquid which wouldn't dry quickly while grinding the pigments and it helps the Poly-Tone flow out the brush marks before it drys.

You grind the pigments with the pestle until you get a good even color mix.  You can see the color change as you grind it together.

 The hardware store sells empty paint cans.  My little paint spatula bends nicely to scrape most of the mix from the mortar.  When I did this with dope I used a little thinner to wash the last of the pigments from the mortar.  The Poly-Tone is already very runny so I didn't want to add thinner.  Instead I cleaned it a couple times with a couple tablespoons of the clear Poly-Tone.  It worked pretty good but I didn't get it as clean as with thinner so I used 1/4 more pigments to allow for some not getting to the can.

 Once the pigment mix was in the can I added the aluminum powder.  For this color it takes 14.75 ml, 3 teaspoons of aluminum.

Then I fill the can 1/2 with Poly-Tone and shake it vigorously for 3 minutes.  I don't know if less will work as well but 3 minutes is all my arms can take.  I then finish filling the can and shake it another minute.  The Poly-Tone is so runny you need to stir it often while painting.

 I start with the lightest color and work to the darkest so each color can overlap about 1/4".  The beige seems a little lighter than the dope on the fuselage but the other colors match very well.  2 coats seem to get a good even color.

 The process is pretty simple.  I draw the pattern on the surface with a soft lead pencil, which won't bleed through the Poly-Tone.  The patterns used by each of the SPAD subcontractors were so consistent that they must have had a pattern they traced for each surface.  Mine were free handed from my sketch.

I mixed a quart of each color, except Black for which I only made a pint.  It looks like I'll need another quart or 2 of beige and light green.  Originally I planned to mix a gallon of each of these colors but I'll never use that much.

I finished the center section and ailerons.  I've got one coat on the top of the lower wings, none on the upper wings.

 I also got the first coat on the blue for the lower wing roundels.  The blue and the black both seem much weaker with Poly-Tone than they did with dope.  I probably could have doubled the amount of pigments in the blue, and I used 4 times a much lamp black to get it to cover in 2 coats.  Mind you, I used 4 teaspoons of lamp black in a pint of Poly-Tone, and I have 5 quarts of lamp black dust.  I won't use it up in a thousand years.

I did find the Poly-Tone a pain to brush compared to dope.  It runs easily and you get bubbles easily while brushing.  I'm getting the hang of it and it looks great.  I really like the look.  Because of the aluminum powder you see every brush stroke so it has much more life to it.  It also looks Like WWI French Camouflage would have looked.