Dark Blue for Cobalt Blue glass

[trytopaint]

Hey all you paint experts.
I could really use a pointer on making a really dark blue.
I am painting a cobalt blue glass vase for my Mom for mothers day and she loves cobalt glass. Its not a cobalt blue, looks more like dark ultramarine.
I need to get parts of the vase in shadow REALLY dark. I have put the max of true Ultramarine on and its not dark enough.

Your thoughts??

[wsrea]

Option 1: get ultramarine blue deep. It's darker than ultramarine. However, there is an easy work-around to darken regular french ultramarine.

Option 2: Ultramarine is a dark blue with a tiny reddish tinge. Try adding a touch of dark-slightly-yellowish red (eg, burnt sienna) to some ultramarine. You'll get a predominantly-blue-with-a-tiny-bit-of-blue/red/yellow in it. Blue/red/yellow equals black. So essentially you're mixing black with your ultramarine.

You do not want to mix in a tube black (ivory, mars, etc black) because it will "deaden" the color. Instead you are adding a "chromatic" black made by mixing red/yellow/blue. Mix tiny quantities of each color until you get the proportions figured out. Another chromatic black is approximated by viridian plus a dark red like alizarin or cad red deep, or by prussian blue/alizarin/burnt sienna.

...Or you can buy chromatic black in a tube, but I never saw the point when it's actually pretty easy to mix on the fly.

Hope this helps. Good luck!

[llawrence]

I've used black to darken ultramarine all the time, I think it works well for that personally.

This post from "Show us your palette" seems relevant to the OP:

#121

[Gigalot]

I use black ink lacquer prepared with self made vine black powder and commercial alkyd varnish diluted in turpentine oil. It is glossy and dries less than one hour, also with lowest possible tinting strength but deep black - best for me to make thin shades for red, blue, green, white, ocher and even yellow.

I stopped to use complementary black mixtures because of bronzing effect and and plus it`s color often depends of available light. If you like black color - use BLACK, not mud surrogate!

[querin]

I would use UMB with a black mix of Pthalo green and Alizarin or quin red to make a neutral transparent black add it to the UMB or another blue .
querin

[Gigalot]

Phthalo + Alizarin or Phthalo + Naphtol FBB carmine has a deep black color. Somewhat deeper than mars black. But it has a highest possible tinting strength while I like lowest possible power, even less than green earth PG23.

[llawrence]

Originally Posted by Gigalot

But it has a highest possible tinting strength while I like lowest possible power, even less than green earth PG23.

I like a low-tinting strength black too, convenient for skin tones. I use a natural black earth for that, works well.

I haven't made vine black before, but someday I'll try it out!

[sidbledsoe]

I need to get parts of the vase in shadow REALLY dark. I have put the max of true Ultramarine on and its not dark enough.

Your thoughts??
Try prussian blue mixed with french ultramarine, if not dark enough then add small amount of burnt sienna or an umber to that.

[timelady]

I'm a glazer so when I need a really deep dark blue I alternate thin transparent layers of something like raw umber or burnt sienna and my deep blue, whatever blue that may be. (sometimes ultramarine, sometimes anthiqu, sometimes pthalo)

Tina.

[Art_song]

Mixing transparent colors for blacks are ideal, much better than a black pigment. If the tinting strength is too strong, and typically transparent colors are very high tinting strength, then dilute it with your medium and store it ready to use in a jar or tube, depending on the type of paints you are using. ASW sometimes has a great sales on empty tubes.

[Gigalot]

It is best to make a choose between Monet and other art immediately. Personally, I love Monet, but i love painting more!
I agree that modern synthetic gel medium (which contain a lot of fillers and extenders) is well tested product but I like oil (alkyd) + pigment formulation more while the oil should be used in small quantities.