Dorrart &#; thank you for the quick response. I disagree with the information in your posted response because there is large body of evidence, from a variety of sources, different countries, etc., and also more more recent than what you cited, about zinc oxide problems in oil paint. Zinc oxide has been discussed very frequently here on WC oil painting forums (and it may be almost discussed as frequently as fat-over-lean. )
You can find more information on our web, so please take a look.
To suggest using zinc oxide, while not also explaining the possible problems with it, is to do a disservice to everyone who reads these discussions in the hope of increasing their craftsmanship. Even if you personally don&#;t believe that zinc oxide causes problems, it would be courteous to mention it in your posts.
I find the MITRA (udel.edu) site to be a very accessible and fact-based source of good information. I have copied from that site directly below; note that this is from , and I have bolded the pertinent text:
Reducing Zinc in Whites by Mixing Different Types
Question asked -06-07 10:10:11 &#; Most recent comment -06-10 02:20:20
Oil Paint
I am aware that it is possible that Zinc Oxide can cause delamination and cracking in oil paint layers. Unless there is some new information I missed, apparently there is no known safe amount of Zinc Oxide in the paint that will stop this for sure. I have read that less Zinc content is logically better if you do want to continue to use Zinc Oxide containing oil paint. I would appreciate hearing the latest from any of the moderators here who might want to comment on the following.
I have a large volume of Titanium White oil paint that has a Zinc Oxide content of 15% or less. I am not really wanting to throw it all away. I have decided to use that what only on rigid supports, but would also like to reduce the ratio of Zinc Oxide in it, if I can. Would it be worthwhile to mix existing Titanium / Zinc whites that have higher ratios of Zinc Oxide in them such as a known 15% maximum with Zinc free white paints and are there any lead free pigments such as PW5 / Lithopone or PW21 / Barium Sulfate that might be more apt to help reduce delamination and / or cracking?
On the same topic of the possible problems with Zinc, would it be advisable to avoid using acrylic underpainting layers when using Zinc containing oil whites? How about using oil grounds vs acrylic dispersion grounds with the same whites? And lastly, does the thickness of the layer containing the Zinc Oxide have any impact on the potential for cracking or delamination?
Thanks in advance for your input.
Moderator Answer (brian baade)
[-06-09 10:24:35]
Sorry for the delay. I was away from home for a few days. I have sent this question to a couple of our moderator who are more knowledgeable about these particulars.
Moderator Answer (mirjam hintz)
[-06-09 12:39:30]
To our knowledge there are no conservation studies that were dedicated to finding a safe level of zinc. In Sarah Sands research she found that decreasing zinc content dramatically, going from 39% down to 3.6% did not change the brittleness of paint in most cases (see https://www.justpaint.org/zinc-oxide-reviewing-the-research/). We know of no pigment combinations that would prevent the embrittlement of zinc. Whether oil paint becomes more brittle when painted over zinc-containing acrylic paint layers, we currently don&#;t know yet but are investigating. We would not expect other acrylic colors of zinc-free dispersion grounds to cause adversary effects.
Thicker layers of zinc white oil paint would certainly cause more severe cracking and lifting. It would probably be best not to use your titanium-zinc paint on any artwork that you care about. Maybe you know somebody who is just starting out painting you could give that tube to.
Best,
Mirjam Hintz (Golden Artist Colors)
Moderator Answer (george o&#;hanlon)
[-06-09 15:26:55]
&#;Without further research on the subject, as Mirjam mentioned by Golden Artists Colors, there is no reasonable assurance that oil paint containing any amount of zinc oxide will not rapidly embrittle. We started a study with different types of zinc oxide pigment, in different oils and in combination with other pigments to further study the behavior of zinc oxide in oil paint. In particular, we are studying the effect zinc oxide in primers has on an oil paintings. The results are still several years away.
Stage two of mixing a color: Determining the value.
In our last post, we discussed the first part of mixing colors and went through what pigments you need to mix any color. We narrowed it down to nine pigments that we can use to create any hue and can use these pigments to mix hues on our color wheel.
For more information, please visit Pairs Horses Chemical.
In this post, we are going to go through the second part of mixing a hue and that is determining its value.
In simple terms, that means determining how light or dark a color is. The colors all around us, have different values and when mixing a hue, we need to know what value level it is.
The reason why this is so important is that you don&#;t want your artwork to have all the same value hues. You need contrast and one way to do this is by using colors of different values. Often when teaching, I tell students to make sure they have the darkest parts and lightest parts more evident and it really brings out the painting.
The way to determine the value of a hue is to use this value wheel or squint your eyes and you will see the lightest and darkest values easily. Determining the value of a hue is the hardest part of mixing a color as it&#;s a tricky skill to master. If everything was in black and white it would be easier to determine. But often you are looking at a color that isn&#;t black and white and you have to determine its value.
Plus some pigments are naturally a darker value, like blue and red are a darker value than yellow, which makes it even more tricky to determine.
Mixing the right value hue:
So once you&#;ve determined that the hue you are trying to mix is a lighter value, the natural default would be to just pick up some white and lighten a color. But doing so will make your colors flat.
Also, using black to darken colors will create flat colors.
So what&#;s one to do?
First of all, calm down. I&#;m not going to leave you hanging!
Here are the simple steps you need to know:
I find that this knowledge of making sure you&#;re hues aren&#;t flat can really separate your artwork from being on a basic level to taking it to the next level. Your paintings will go from lifeless and flat, to alive and vibrant.
So to summarise, determining the value of a hue is crucial when mixing, but be careful when adding white or black as they flatten a hue. You want to add another color back in when you are mixing a pigment with white, usually, a pigment that is already in the mixture.
This image above is with just Alizarin Crimson and Titanium White
This image above is with Alizarin Crimson, Titanium white and Cadmium yellow pale added in to make it more alive.
The only instance when I find you can add straight white without needing to add another color is blue for skies. There adding just blue and white works fine.
As well, you do not want to paint using a lot of white at the beginning of a painting. I like to add the lightest values that need white towards the end of the painting or leave space in the painting for the light value hue to be added. This is because adding white to your painting too early can cause the other colors to blend in and you end up with all the colors becoming flat and the white taking over the painting.
Use white wisely when painting and don&#;t jump to add it everywhere. Often I tell a student to wash their brush and paint a section again, as I can tell they have white on their brush and it&#;s subtly deading their hues.
So make sure to keep your paintings alive and vibrant and use your white wisely and if this totally confuses you, here&#;s simpler advice: Next time you want to just use white to lighten a color, first see if you can add a lighter value hue or just begin to notice what happens when you add white to a color. Slowly, you will get used to using the other pigments to create lighter or darker value colors and when you add white or black you will make sure the hue is still &#;alive&#; and not flat.
It&#;s a mindset shift and a process to learn, but a very important part of building up your skills as an artist.
So just remember- WWW? (What&#;s with the White?) next time you paint.
In my teacher&#;s training course, I go through &#;Palette rules&#; that teachers can teach their students to set them up to mix colors correctly. Watch our free masterclass to know how to teach any student of any age art:
In my kid&#;s art courses, we focus very heavily on mixing colors without white so that students get used to mixing without jumping to the white. Join the waitlist to know when we open our doors to our signature art courses for kids and teens.
Want to learn how to paint and draw yourself? Join the waitlist to know when our beginner&#;s course launches.
Want more information on white pigment? Feel free to contact us.