Posts Tagged ‘supplies’


Testing Gesso Made from Cellulose Gel

October 1, 2017

A few days ago I was scanning the internet looking for raw art supply materials, and I came across a site that sold a gesso mix using methyl cellulose. This was “Eco Gesso” sold by Natural Earth Paint. I was surprised, but intrigued. I’ve used methyl cellulose (MC) and Carboxymethyl cellulose (CMC) as art mediums before, but not in this manner. (Here’s a link to a previous post using MC mixed with oils.) I’ve made gesso before using rabbit skin glue (RSG) or casein for many years. My first reaction to one of this type was that MC or CMC would be too weak by comparison to serve as an effective foundation for painting; however, being naturally curious, I decided to try to make some of my own, and test it out. A $30 kit from Natural Earth sounded like too much to pay for experimenting.

I’ve read that CMC has a stronger bond than MC, so I took a teaspoon of CMC powder, and converted it into a gel by adding eight teaspoons of distilled water.

Next I added water to thin this out, and solids to make the gesso. That’s the gesso in the metal bowl.

I took a scrap panel I had, 8 x 10 inches, patched it up a bit, and applied the first thin coat.

Here’s the finished panel with 8 coats.

I had to make 3 different attempts at this. The first batch of gesso I made, using the same ratios of CMC gel that I use with either RSG or casein was too thick, and the end result on the dry panel was dusting off too much, leading me to believe the glue was too weak to hold that much gypsum. This panel is the second attempt, which had 25% less solids, but the same glue strength. It went down very smoothly, and although it didn’t powder off as badly as the first one, it still was rather weak. I could wipe the surface and get a powdery residue. I made a third attempt by using less water in the glue, and it didn’t brush on as smoothly, but still dusted off.

In summary, this gesso is much weaker than those made using RSG or casein, just as I first suspected. However, it’s not completely unusable. It’s like painting a fresco. Wet paint will turn pastel from mixing with the surface powder, but still hold. You can see the difference of this burnt umber paint on the CMC gesso panel compared to the same paint on a scrap piece of watercolor paper. If one doesn’t mind that desaturation of color, then it can work acceptably with either water based or oil based paints. The CMC powder can be found online very easily. I bought mine at a local ceramic supply store. It doesn’t have to be heated or refrigerated like the other glues, but can grow mold. A drop of preservative, like thymol, will prevent that. Personally, I’ll stick to the other glues. They make a stronger surface and are more versatile, but it’s good to know there’s an alternative.


Shiva Casein Paint Test Update

July 24, 2017

To follow up on my previous post, I had found that one of my Richeson/Shiva paints, Cadmium Green, transferred to a dry paper towel with just some light rubbing after the paint had dried. Now I wanted to see if other tubes I owned had this same problem. They do.

This picture shows a sheet of paper on which I painted 1 inch swatches of all the different tubes of Shiva paints I have. The paper towel at the bottom shows pigment from each swatch that transferred over. I did not dilute the paint at all with water, and did not apply the paint too thickly. All of the paints smeared easily when rubbed, some more than others, with the sole exception of the Raw Sienna. The ivory black in particular smeared very badly, and even after a day of drying felt to have a weak paint film.

Since all of the paints are old, in some cases decades old, I asked around to other people who used these paints if they could test any tubes they might have that are newer, and see if they had the same problem. I heard back from a couple people. One person had some Richeson caseins that were only months old, and found they had the exact same pigment transfer problem. The other artist rubbed the surface of paintings he had made that were at least 3 months old, and said no paint at all rubbed off. What this tells me is it might be possible that if the paint is allowed to cure for awhile longer, the pigment will adhere better and not rub off. This strikes me as a strong possibility. So, I think I’ll do a new test on paint swatches that sat undisturbed for a month or more, and then see if any pigment rubs off.


Comparing My Casein Paint to Shiva Brand

July 22, 2017

I wanted to follow up on my previous post where I made my own casein white paint, and see how well it compares to tubes of the Shiva paint I had, and discovered something interesting. I used the paint swatch I made testing my paint on a sheet of Strathmore textured “Art Paper” 65lb.

I painted a small swatch of the Shiva titanium white, undiluted, next to the swatch of mine I had made. It may be hard to tell in this photo, but I noticed their white has a slight off-white yellowish tint to it that mine does not. I let this dry for a day, and came back and gave both a buffing with some colored fabric, and saw no transfer of pigment from either swatch. Next I placed a small piece of cellophane tape over each one, rubbed it, and removed the tape. Both transferred some paint, but more paint came off the Shiva swatch, lifting almost all the paint from the paper. The casein binder I used to make my paint was over a year old, so later I’ll see if a fresher batch performs better.

Since that tube of Shiva white is many years old, I thought I’d test a newer tube of Cadmium Green that I had to see if it performed any better. Rather surprisingly the pigment adhesion was worse. I let that paint swatch dry for about 3 hours, and rubbed the surface with a paper towel. You can see quite a bit of pigment rubbed off. The tape test pulled off quite a bit of pigment also, and the way the pigment transferred was not in sections of paint, but powdery like what I saw on the paper towel. This tells me that the adhesion on this tube of Shiva paint is poor. Granted, it’s about 5 years old or so, but it shouldn’t come off this easily. I have commercial tubes of gouache that adhere better than this. I hope the newer Richeson brand of Shiva adheres better. Now I want to test the rest of the Shiva paints I have. This is not terrible, but surprising. This paint adhesion is not much better than soft pastel.


Homemade Scaling Caliper for Drawing

July 10, 2017

I was browsing around on the internet this morning looking at drawing tools, and I stumbled across a youtube video of a fellow making a proportional drawing caliper. I’ve used these before, but lost the one I had bought some time ago. This sounded like a good project to fuss around with.

A drawing caliper is a measuring device made of two crossing sticks that allows you to scale up a measured distance depending on where you attach their intersection point. For example, if you set the small end to be 1 inch apart, with the center screw set to 2X, the points at the other end will be 2 inches apart. As long as that intersecting point stays the same, all your measurements will have the same proportion.

There are commercial calipers you can buy, such as this one from AccuraSee, but the one in Jen’s video looked pretty easy to make, and it was; however, I discovered a problem with three of the hole placements.

I decided to make mine out of two strips of balsa wood (3/32″ thick), being easy to cut and shape and not too flimsy. A 6/32″ screw and wingnut holds the pieces together. I printed out Jen’s diagram that he linked to on the video, and used that as a template for the balsa (1″ wide, 9″ long.) I drilled 5 holes according to his diagram, and tested the scaling by lining up the two ends with two rulers. The 1:1 scale in the center was easy to test since it’s in the direct center of the 9 inch strip. Hole #2 also measured out correctly by scaling up 1 inch to 2 inches on the other end, as you can see above. There was a problem, however, with the three other holes not being placed correctly. The 3rd hole should have read 3 inches, but instead I got 3 5/8 inches. hole #4 was 4 7/16, and hole #5 was 5 9/16.

I needed to make a new caliper with those three holes in different spots, and to do that I cut a slot between the three holes with this opening moved slightly forward (towards hole #2.) That way I can adjust the placement of the screw to figure out the new location. Doing this, I discovered hole #3 needed to move 1mm in Jen’s diagram, hole #4 moves 3mm, and hole #5 moves 4mm. Just that tiny adjustment made a huge difference on the other end.

I made marks on the balsa strip where the new holes needed to be, and cut and shaped two new strips of balsa. Now the calipers scale correctly in measurements of 1:1 up to 1:5. Below is Jen’s diagram that I’ve marked up with red lines showing the new placements. You can print this out, and see for yourself if it works to your liking. Balsa doesn’t drill very well, so I may make a new one later out of stronger wood, like oak.


Studio Tip – Binder Clips

January 26, 2016

I’m taking a short break from the painting to show a tip for using binder clips in the studio. I use them to keep my paint tubes organized, or for hanging sheets of paper or canvas. You can buy these at an office supply store in various sizes. These are “medium” size, 1.25 inches.


To slip the clip over the plastic hanger, I squeeze the metal handle and remove them from the clip. I then slide them over the hanger, and squeeze them back on clip.


I can now place the hanger on a rod and clip the bottom ends of paint tubes to them. This allows me to organize the paint by medium or paint color – however I need them. To keep them from sliding down the hanger, I can tie a wire “twisty” on the handle. The clips are strong, and will hold even a large tube of paint.


Alternatively, with this particular type of metal shelving I have, I can slip the clips over the metal rods, and not use hangers at all. You can also get some peg board hooks at a hardware store, and slide the clips on those.


Another use for the clips and hanger is to hold sheets of paper or canvas using these plastic “slide-grip” binders sold for report covers.


They’re less likely to damage the sheets than the metal clips themselves, and will keep the sheets straight. This can be especially useful for wet surfaces that that need to dry. With the painted side facing the wall, dust is less likely to get on the surface.



Paint Storage Tip: Gravity Is Your Friend

July 22, 2015

Some fatherly advice I received years ago from dear old Dad was to store my containers of liquid, in particular cans of paint and such, upside down. The demon of air will dry out paint, or cause it to get a dry skin layer inside the can as air that penetrates through the lid. However, when the wet liquid presses against the inside of the lid there’s less air to dry it out, and the paint will last longer.


In this photo above you can see a few small plastic jars of some recently made gouache paint turned upside down on their lids. This is how I store them. Sometimes I put labels on the bottom. Behind them is a jar of Golden Acrylic Gesso, a bottle of acrylic medium, and some paint tubes. The bottle of medium is a little unwieldy on its cap, so I have to place it in a drawer in such a way that it won’t tip over, usually against other similar bottles stored in the same way. The paint tubes can be a problem since most manufacturers use very small caps that won’t let you balance the tube upright. Liquitex tubes are nice and large for that, but not most other brands. Alternatively, you should squeeze the tubes from the end, forcing the paint to the top and get the same benefit.


This is also a good way to store any cans of left over house paint you might have in the garage. Be careful of potential leaks, however, and put a plastic sheet underneath, just in case.

The motivation for this post was my reading that Golden is going to start labeling their cans upside down to encourage people to get use to this way of storing their supplies. Good for them.