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I am currently involved in running a series of tests for an upcoming project. I want to create a series of silverpoint drawings on some uniformly tinted 5" x 8" HDF panels. For the dark values in silverpoint I want to achieve a mid to three quarter tone gray (but no more), which I imagine touching up with some white highlights as a final touch.
So I'm trying to decide what is the best way to prepare the ground, do I go traditional (chalk gesso) or modern (acrylic)?
For to the acrylic direction, I have already created two tests:
One is a smooth yet absorbent HDF surface prepared with Golden Acrylic Gesso (which I have tinted using acrylic tube paint). 4-6 coats. Lightly sanded inbetween to remove brushstrokes. The tint is good. Over this I brushed a layer of (transparent) Golden Pastel Ground. The result is very toothy and feels like rough sandpaper. Nice. The silverpoint test marks I have made appear to be darker than usual. Thus there appears to be sufficient contrast between the silverpoint and the tinted ground. I imagine touching up the highlights using a white gouache, but havent't tried it yet. Will there be any absorbency issues with that? Should I use acrylic paint or is gouache OK?
The second test is on a smooth yet absorbent HDF surface prepared with Golden Acrylic gesso over which I brushed Golden Silverpoint Ground. This time the acrylic gesso was untinted because I knew I would be introducing the tint through the Golden Silverpoint Ground - which is opaque. The result feels less toothy to the touch, (actually it feels like smooth plastic), but does appear to take the silverpoint test marks well enough. Made repeatedly thgese could become the mid-value gray tonality I seek? I haven't tried the white gouache highlight test here either but my questions are the same. Will there be any absorbency issues with that? Should I use acrylic paint or is gouache OK?
However, my main question concerns the traditional approach. If I were to go that direction using RSglue/chalk gesso, I imagine adding some terra verte and maybe a small bit of burnt umber to my gesso ground prep. This would achieve the tint I am looking for. And if these dry pigments were less than 10% by volume (surely it would be even less than that) I think that these should be no problem to the integrity of the gesso. Is that correct?
In addition, I am wondering if there is a way increase the tooth of the traditional chalk gesso ground so as to increase the value of the silverpoint marks? Marble dust or other additives, etc...? Coarse sanding of the final surface? Any suggestions?
Thanks for the feedback. I really appreciate being able to ask my questions of well informed resources.
Move this whole section up, swapping places with the section above it.
Let's start by having you read through previous posts about similar subjects
and then we can focus on subjects that we have not delved into before. The
following is a good one:
This one has some good info in it as well:
As does this:
Feel free to ask about anything not covered in those.
Hi there, Tom Mazzullo here, I've done some research into these questions and, although I'm not expert with these specific issues, I've tested all the materials you're using at least once and can respond with my own experience.
I think to answer at least some of your questions, you could use either acrylic or gouache for highlights over an acrylic gesso ground. Gouache would be water soluble after drying, and thus correctable. I would ask if you plan on varnishing your finished panels (I don't varnish metalpoints, but I know some artists use spray varnish or good quality fixatives)
For the other questions, about traditional RSG ground: to preserve the integrity of adhesion, do your best to keep the ratio of pigment/binder/vehicle the same. Adding 10% pigment means removing 10% chalk. In my experience, too much dry matter and the RSG ground can lose adhesion; too little and it flakes off the panel. RSG grounds are fickle, especially when you begin to apply a hard metal point to them. For increasing tooth in the preparations, you could try bone ash as an additive, say 50/50 chalk and bone ash - it's traditional, inert (wont affect metal cast or tarnish), and colorless (maybe a slight graying of tint). Be sure to first grind it in a mortar, sometimes the grit can be uneven. Lastly, instead of chalk, consider using white pigment - my RSG grounds with pure zinc or titanium oxide make luscious grounds - I don't add chalk or bone ash. It's my favorite ground for paper or panel.
I would have thought that the Ti02, with its
sub-micron particle size, would be a poor choice given its lack of tooth. This is very interesting to read.
Tom Mazzullo knows as much about metalpoint as anyone, and covers the traditional gesso option well. But I love this topic and can't resist adding several more thoughts – I hope some prove helpful to your project.
The abrasion in a metalpoint ground is primarily created by…
1. High Pigment Volume Concentrate (PVC). A ground/paint that has a high solid/pigment content relative to the binder, so that the solids/pigments protrude above the surface of the binder. This creates an irregular, rough surface (on a microscopic level, generally) or "toothiness" that abrades the metal nib.
2. Hardness. Solids/pigments within a ground are very hard; i.e. have a Moh's Hardness Scale (MHS) rating higher than the metal nib being abraded.
Of the two I think hardness is as important as toothiness – but first I want to look at a rough surface.
HIGH PVC/TOOTHINESS. Metalpoint has no binder. Metal marks hold on via a mix of particles getting trapped within the "nooks and crannies" of a support/ground, along with electrostatic attraction between particles.
If a ground is too smooth – i.e. there are not enough irregularities in the surface - metal marks may, over time, lose their "grip" (so to speak) and a drawing can appear to "fade".
However if a ground is very rough (akin to sandpaper) it has larger and fewer interstices into which metal deposits can lodge. A large tooth ground also abrades larger metal particles that are less likely to attach to the surface and each other. So, at some point, too large-toothed a ground makes for less stable metalpoint marks.
For the above reason I don't generally recommend very rough pastel grounds (I've tried several) for metalpoint. I realize you like the Golden Pastel and needn't listen to me…. I just want to clarify what I see as potential shortcomings of a very rough ground.
HARDNESS. To the extent it can be determined, the hardness of the solids/pigments within a ground is one of the most important considerations in creating an abrasive surface. Simply put, if ground solids are harder than a metal nib being drawn across that surface, the ground abrades the nib.
You can add extra solids/pigments to most grounds to increase both PVC and hardness. However, too much added solids can lead to chipping/delamination of ground from support, and/or a brittle, friable ground that crumbles under a metal nib. So, a conservative starting point is adding 5% of the total volume of ground. If there are no problems, gradually increase the amount. Material experts generally recommend no more than 10% added solids to an existing ground. In practice I've added more with success, depending on the binder. Experiment and test (see below).
TESTING SOLID/PIGMENT CONTENT IN A GROUND
1. Flexibility. Apply one or two layers of the amended ground to a flexible support (i.e. 90# watercolor paper). Gently bend in various directions and see how it reacts. If the ground cracks or shatters into pieces = too much pigment. (However, for the actual drawing, always apply multiple layers of a high PVC ground to a rigid support, as you're planning to do via HDF).
2. Adhesion. Do a cross hatch adhesion test to see if there's enough binder for the ground to properly adhere.
3. Diluent Sensitivity. For water-soluble grounds, take a wetted Q-tip and rub the surface to see if ground lifts or dissolves (but don't rub too aggressively or you'll merely remove ground through abrasion). The ground should stay put. If you can't see a white ground on a cotton Q-tip, warp the end with a small piece of wet, blue shop rag.
EXTENDER SOLIDS/PIGMENTS. Extenders must be inert. Particle size is best within the .1 to 2 micron size. A pigment's color and opacity/transparency are also factors. Additionally, some extenders give unexpected results, i.e. I've found that pumice brings out more of a metal's color. There are many options, but here are a few of my favorites for increasing abrasion, followed by the MHS rating. (FYI, a pure silver nib is 2.5 MHS; sterling silver is about 3 MHS).
Bone Ash 3
Zinc White 4
Titanium White 6.5
Of course, always wear a dust mask when working with powders or sanding a high PVC ground - especially silica!
TINTING A GROUND. Tint with either powdered pigments, dispersions or compatible paints. I tint with powders only if they're large micron size, low tinting earth pigments (because they disperse readily). For all other pigments I use a commercially produced dispersion to tint.
HEIGHTENING WITH WHITE. I've used all of the following, at various times, for white highlights on metalpoint, and all have worked well for me, no sinking in. They have different pros and cons (solubility, density, fineness of line, etc.): White Chalk, Colored Pencil, Pastel Stick, Chinese White Watercolor, Gouache, Casein, Egg Tempera, Acrylic Paint.
COMMERCIAL GROUNDS. Finally, If you're content with Golden's regular Acrylic Ground, that's great. But I've had a lot more luck with metalpoint on Golden's Sandable Gesso (excellent), Absorbent Ground (good) and their High Load Acrylic Paints (good).
Two other synthetic polymer grounds that work really well for metalpoint are Art Boards Gesso (one of my favorites) and Natural Pigments Tempera Ground. Both sand well and are nicely abrasive.
Extender solids/pigments may be added to any of these commercial options to increase abrasion or to tint.
My all-time favorite metalpoint ground is Natural Pigments, Rublev Traditional Silverpoint Ground. It comes in powder form and needs to be hydrated (two hours), then warmed in a double boiler. It can be applied right away but, like traditional gesso, becomes smoother if put in the refrigerator overnight, then rewarmed and applied the next day. Of course, you can make a traditional ground from similar ingredients yourself, but the above is convenient.
I prefer all of the above over traditional gesso for metalpoint – but every metalpoint artist has their favorites, and time will tell what works best for you. Good luck with your project!
First and foremost, thank all of you for your informative responses.
You have given me some homework!
I should have mentioned that I do have experience in silverpoint. I have done a number of silverpoint drawings which were always executed on a panel prepared with traditional (white) chalk gesso. I always add 10% zinc white to my chalk filler – without changing the RSG to filler proportions. It works fine (no chipping) and I absolutely loved the tactile quality both of the gesso as well as the meditative process of drawing in silver. That's my silverpoint 101.
Additionally, I do have in my possession two silver points. One is pure silver, one is sterling. I don't know which is which. Any quick way to tell?
For this new project, from a tactile point of view, I would definitely prefer to use a traditional ground, if possible. I don't really like acrylic (because it's too plastic) but am trying to spread my wings. Overall, my main goal is to achieve a good contrast between the ground and the silver, which can later be enhanced by creating a good contrast between the ground and the highlights (using gouache, etc…). But the overall effect should be evanescent, so I'm not trying to get dark blacks.
Brian, I read the links you shared. There is a lot of information there to process. My main question after reading through the links was: is it the hardness of the mineral/additive elements in the ground that determines the darkness of the metal point stroke? Then I read Koo's response to my question where she emphasizes that, yes, it is. Obviously, there are many factors, but it's good to be aware of the most important ones.
Tony, thanks for your responses. I may try a RSG ground with zinc white + 10% terra verte (since that is the tint color I am envisioning for this project). But the terra verte powdered pigment I have (from a reputable color shop in Brussels, I live in Bruges) is not very saturated. I may try to obtain some different samples from Kremer Pigment (Germany)? I may try to obtain some bone ash while I am at it. And of course, some zinc white.
Koo, Thanks for all your information.
As noted above, I'd prefer to work with traditional grounds but am trying to experiment with other materials, too. My acrylic experiments were based on the third link from Brian which was a response to your earlier questions about Golden Pastel Ground vs Golden Silverpoint Ground.
In both cases that I described, I tinted the Golden Acrylic Gesso or the Golden Silverpoint Ground with acrylic tube color because I had read on Kremer Pigments that real green earth dry pigments are iron II silicates which react poorly to acrylic dispersions. By adding tube colors it may have increased the plastic feel of both grounds? (I don't know) But in the case of the Pastel Ground that did not matter because it was superimposed over the tinted gesso. Yet I was surprised in the end to experience such a tactile difference between the two- the Golden Silverpoint Ground felt like smooth plastic and the Pastel Ground like sandpaper(!). Not at all sure I want to go that coarse (or that plastic, either). ;-)
Thanks to all.
Sorry, I forgot to add my name last time.
Tom or Brian may be able to answer this better than I, but here are a couple of possiblities...
- Sterling is an alloy of about 92.5% silver + 7.5% copper. The copper gives a bit more hardness; sterling silver is approx. 3 Mohs hardness whereas pure silver nib 2.5. Rub each nib over a ground and see if one feels softer, abrades more readily - that would be the pure silver.
- Silver and copper tarnish differently. Copper also colors differently depending on what element it reacts with (oxygen, sulfides, ammonia, etc.), transforming to either a reddish brown, black, yellow green, or verdigris. The ground also affects how a metal tarnishes! Given how unpredictable tarnishing is, tarnish color is not a great predictor of a metal. However, in my experience, sterling, with it's copper component, tends to have a hint of color when it tarnishes; pure silver tends to tarnish a bit darker than sterling. So you could do accelerated tarnishing and see if you note either of those differences. A couple of ways to speed up tarnishing: 1. Add a few drops of egg yolk to a ground; 2. Put the metalpoint marks, along with a jar of chopped garlic or onions, or some apple cider vinegar, into a sealed container (like a pyrex dish with a lid) for a day or two. K. Schadler Tarnishing.png
Golden makes fantastic products, but frankly I very much prefer their other two gessos that I mentioned to their actual silverpoint ground. I too don't like a plastic feeling to a metalpoint ground. But if a synthetic polymer ground has a high enough solid content (i.e. a very high PVC), it won't feel overtly plasticy - it feels fairly close to traditional gesso. I would say this is true of the Golden Sandable Gesso, Art Boards Gesso, and Natural Pigments Tempera Ground.
Please let us know how it all works out.
In terms of differentiating .999 from sterling, I will give a very long response to what is really a very short answer.
It would be difficult to differentiate sterling from .999 silver
on the small scale, at least if you do not have access to analytical tools. One
could perform x-ray fluorescence spectroscopy (XRF) and see if there is any
copper (or other alloys as nickel and other metals are also used to harden
silver to make serviceable jewelry). There are even non tarnishing silver
allows that contain germanium that have the same 92.5% of silver as sterling.
For less instrument heavy analysis, one could do a weight vs
volume to determine whether there is any metal in the point other than silver.
.999 silver is 10.497 g/cm3, sterling is 10.36 g/(cm3. This
would require a very accurate scale as well as enough of the metal to
accurately determine its volume to compare to its density.
Outside of XRF and the above, the best means of testing are
wet chemical analysis or assay. These require a small amount of material to be
permanently removed from the sample. One would likely have to pay a lab for
this. There are more simple, DIY chemical spot test that can check for the
presence of copper (not how much, but the presence). Here is a link to a paper
discussing this: https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/canadian-conservation-institute-notes/test-copper-lead.html
Sooo, unless you wanted to spend a lot of time, energy, on ambiguity,
and/or money. It is probably fine to just work with empirical tests like, “this
feels softer, and I need to resharpen frequently, or this is quite hard. Even this will not reveal if a metal has been hardened
by tempering or even “cold working” as opposed by being inherently harder due to alloy content. It
is best to buy from someone you trust. It is usually better to spend one’s
precious time as an artist perfecting one’s craft or creating meaningful art
while relying on trusted manufacturers to give them quality products
with accurately described ingredients. In lieu of that, rather than spending
time testing pre-purchased materials, it is really relatively easy to make
one's own stylus from a known silver article (silver bullion or bars,
.925 silver jewelry, or .90 pre 1965 US dimes, quarters, ½ and dollars in the
US. Different dates are appropriate for other countries. Most on this forum
know all of this. I write these responses expecting them to be reviewed by neophytes
and in the future and it is preferable to write it once rather than many times 😉.
As always, other moderators may know something about this
that I do not. I do, however, doubt that they will greatly disagree with my
penultimate paragraph 😉
BTW I love that all of the great information were are generating (on this subject and others) is being archived here on MITRA by the University for future readers. Thanks all.
Thank you Koo and Brian. Sorry, Tom, I mispelled your name - but I did just order your book.
I will experiment with some of the harder grounds that you mention, Koo.
The silverpoint nibs I have in my possession were from a reputable silversmith here in town. it's just that that was 15 years ago and though I tried to label them in their respective stylus' my writing is now indicipherable. If I decide that the difference is cruciall to me for this project it will be easier to replace them from the same source (and keep better records) than to get involved in the complex questions of deciphering the content of the metal.
Thanks again to all.
Brian's point is a good one - much simpler to buy a new nib, less than a $1 on a wire jewelry site. Thanks for clarifying things, Brian.
Hi Ellen, I've noticed that sterling tarnishes faster - it's not a short term solution, but if you leave both points out in a humid environment, the sterling will brown quicker. Tomorrow I will do the smell test. You may know that one tests for gold vs. brass by rubbing the metal between your fingers and checking for a metallic odor (brass) or no odor (gold). Perhaps the small amount of copper in sterling will have an odor compared to pure silver?