Skip to Main Content
Sign In
Toggle Navigation

Open the Navigation Management window, which can be used to view the full current branch of the menu tree, and edit it.

  • Instagram
  • Facebook

MITRA Forum Question Details

Image Picker for Section 0


  • Using natural soil pigments on paper?ApproveRejectUn-ApproveSubscribeUn-Unsubscribe
    Question asked 2019-01-24 06:06:43 ... Most recent comment 2019-08-14 19:00:36
    Paint Making Watercolor Pigments

    ​Dear MITRA Moderators, 

    I want to create a three-layered paper piece based on the element of Earth. I'm doing a four-piece suite, one for each element, and am involving each element directly (for fire, I burned the edges of the paper), etc.

    I'm using a 300 lb paper for the first layer, and would like to use natural pigments including clay soil. I'll adhere a second layer (140lb paper) to the first with a brayer, using a product recommended to me by the art supply representative (Daniel Smith Transparent Watercolor Ground). I'd like to use natural pigments here, including clay soil and a homemade walnut stain. For the final paper layer, I'll adhere a thinner paper (I think it's 90 lb) and use watercolor pencils. I plan to distress the first and second paper layers respectively to expose the pigment underneath.

    Does this sound like a sound approach? Can you use regular clay from a yard or creek? Is homemade walnut stain ok to use, or would it be too acidic, etc? 

    Many thanks! I'm really excited about this project!

Answers and Comments

  • EditDeleteModerator Answer

    ​Regarding the clay, it depends on where you live and what portion of the clay is organic matter which might break down. Some soil has a lovely color when freshly dug due to plant material, but the organic components might not prove durable. Clay that is stained with oxides and ochres will be more reliable over time. As far as the walnut ink is concerned, any vegetable-derived colorant can be vulnerable to color change from exposure to UV light (though anyone who has hulled black walnuts may find it difficult to believe that the stain will ever fade willingly). If I were offering such a piece as you are describing to a collector, I would suggest display under protective glazing, out of direct sunlight or intense illumination, and recommend that the piece be stored at intervals, to reduce total exposure. This is really good advice in general for watercolors where some pigments are not of the highest lightfastness.

    Matthew Kinsey, Utrecht Art Supplies
    2019-01-24 20:47:58
  • ApproveRejectUn-ApproveUser Comment

    ​Dear Mr. Kinsey, 
    Thank you so much for your thoughtful response. Apologies for the delay in my reply -- I've been out of town. 

    I am in NC, so yes, we do have proper clay, though the concerns you raise about the organic content has made me rethink its use. Perhaps another choice can help me balance the conceptual idea with longevity. I am wondering if there is a way to say boil the organic material from the clay, leaving the pigment behind? Or perhaps I could give a nod to the concept by using only natural pigment paints. 

    Thanks also for mentioning the lack of lightfastness with the walnut stain.  You are quite right -- I would have thought it to be the most lightfast thing I could use!

    I appreciate the time of all of the moderators; thank you for providing this resource. 


    2019-02-19 22:30:18
  • EditDeleteModerator Answer

    ​I'm afraid I can't even hazard a guess about boiling or otherwise refining clay. I like your idea about using pigments from terrestrial (mined) sources. Some historical colors have gone extinct as mines have become played out, (the original Venetian Red, Caledonian Brown, Cappagh Brown, and some other ochres were mined until the source was exhausted) but there are still some really great pigments that are not synthetic.

    Matthew Kinsey, Utrecht Art Supplies
    2019-02-20 22:39:27
  • ApproveRejectUn-ApproveUser Comment

    ​Dear MITRA,

    Regarding the three-layered watercolor piece I initially described above, I have been having a lot of fun exploring natural pigments for my "earth" theme, including some made from minerals and semi-precious stones.

    While I prepare for the final piece, I have two new questions: 

    1) I had the idea of using salt in the watercolors to create some fabulous, effortless "dirt" textures; the technique itself also adds to the earth theme. While this is an old watercolorists technique, I am primarily an oil painter, so I wondered if I leave a bit of salt behind on the paper, being hygroscopic, would that be bad for longevity? (Read: I'm having a bit of trouble getting all of the salt off of my studies, haha.)

    2) An art supplies store employee recommended a name brand transparent watercolor ground to adhere the three layers of paper together. Unfortunately, the manufacturer never replied to me to confirm whether or not their product would work for this purpose. I welcome your thoughts on this, or should I consider using a different product? I will be distressing the paper at certain strategic places in order to reveal the previous paper layer, so the art supply employee thought that the transparent ground would be a boon.

    Many thanks for your time and expertise!

    2019-07-17 01:11:30
  • EditDeleteModerator Answer

    The salt will remain reactive to changes in RH but really, your piece should be stored in a stable environment anyway. I have seen many works where there are effects that had to been created using rock salt and they at least initially appeared in fine condition but that is not a good test for future longevity. I would think that it would be good to brush off what you can before framing etc. I will ask a paper conservator to comment on what NaCl does to cellulose.

    There are a couple of transparent watercolor grounds on the market. I have to admit that I do not know what such a ground would be composed of. I am assuming it is some transparent filler like fumed silica or glass platelets etc., leanly bound in an acrylic or PVA dispersion. Without more info, I cannot really comment. Perhaps others here have a greater knowledge of these grounds.  

    Brian Baade
    2019-07-17 12:09:04
  • EditDeleteModerator Answer

    ​If you are using a watercolor ground as a wet adhesive to stick paper to paper, if the ground is acrylic-based, it will likely work. A simple adhesion test conducted using scrap paper will reveal whether it will bond strongly enough. Gloss acrylic mediums are usually the best adhesives. Matting agents like the ones Brian listed as possible ingredients interfere with some of the like-to-like adhesiveness of acrylic products, but if the ground will stick permanently to one sheet ofpaper, it should stick two pieces together.

    Matthew Kinsey, Utrecht Art Supplies
    2019-07-18 16:26:53
  • EditDeleteModerator Answer

    I received this for Joan Irving Senior Paper Conservator of Winterthur Museum & Affiliated Associate Professor of the Winterthur and University of Delaware Art Conservation Program. This really is a very good question – and I can’t recall anything in the conservation literature about this topic.  As we discussed, the main problems with the NaCl might be more theoretical than actual. If the watercolors are kept in a stable environment and in acid-free enclosures (mats, folders), they will probably be fine. Theoretically, the hygroscopic nature of the salt could raise the moisture content of the paper (with potential for foxing, mold, etc.). The other theoretical downside would be possible disassociation of the Cl ions, which could yield degradation products such as hydrochloric acid. However, most watercolor papers are really robust – generally quite thick and very well sized; sizing provides lots of chemi-mechanical protection and reduces the porosity and susceptibility of the paper to atmospheric pollutants, moisture, mold, etc.

    So, if any paper could tolerate common sodium chloride – it would be a well-sized, rag, watercolor paper. It would be helpful to mat these objects in good quality, 4 or 8-ply, alkaline, 100% rag boards with zeolites (which are desiccants as well as good scavengers for atmospheric pollutants).

    Brian Baade
    2019-07-19 15:19:32
  • ApproveRejectUn-ApproveUser Comment

    ​Thank you Brian and Matthew for your thoughtful replies. 

    My next step is indeed to do a test to see how the watercolor ground does as an adhesive. I wasn't sure whether sticking ok now would be a good indication of staying properly stuck in the future...? I'll compare it with a test of the acrylic medium I was initially considering. The vehicle listed for the watercolor ground is indeed 100% pure acrylic emulsion, though the proprietary ingredients are not listed.

    Thank you for the extra research about the salt. Very informative and thorough! You've given me some great information with which to proceed. I am using three weights of papers -- #300 on the bottom, #140 in the middle, and a thin piece for the top (#93) which would likely be too thin for the salt technique anyway, since it won't take much water to begin with.

    Many thanks for what you do!

    2019-08-01 15:35:46
  • EditDeleteModerator Answer

    ​In my experience, paper bonded by a wet-applied acrylic product (as opposed to heat fused) will remain bonded indefinitely if initial adhesion is good.

    Matthew Kinsey, Utrecht Art Supplies
    2019-08-01 15:56:55
  • ApproveRejectUn-ApproveUser Comment

    ​Thank you, Matthew -- that's what I was thinking. I'll give that a try tonight! All the best.

    2019-08-14 19:00:36

Page Settings and MetaData:
(Not Shown on the Page)
Page Settings
MetaData for Search Engine Optimization
MITRA Forum Question Details
This page cannot be accessed until you accept the Terms of Use, which can be found here.
Please note that this Terms of Use system uses cookies. If you have cookies disabled you will not be able to accept the agreement. If you delete our cookies you will need to re-accept the Terms of Use.
  • The Department of Art Conservation
  • 303 Old College
  • University of Delaware
  • Newark, DE 19716, USA
  • Phone: 302-831-3489