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<\/a><\/p>\nApplying a primer onto your canvas seals the surface and prevents oil paint from coming into contact with the linen or cotton fibres which would slowly be damaged by the oil, becoming dark and brittle over time. Some clear primers can also act as a stiffener for stretched canvas, so it will wobble less. Wood panels do not need to be sealed from oil for longevity but priming will give a better surface to paint on, by making it less absorbent and evening out the absorbency of the wood which would otherwise have different amounts of absorbance between the grain lines and the wood between them.<\/p>\n
At Jackson\u2019s<\/a> we have a great selection of white primers but we also have a pretty good selection of clear ones. I\u2019ve done some testing to find out the characteristics of each one. The three main things most artists will be interested in are: how clear it is, if it is a slick or absorbent surface because that affects how it feels to move the paint around, and how good a value it is. I answer those questions and also take a look at other characteristics including ease of application, drying time, and how well it blocks oil penetration, as well as many others.<\/p>\n Matt mediums or rabbit skin glue are commonly used as sizes underneath a white gesso\/primer, but if you do one or two more coats, they can then be the ground as well, which many artists do. So in addition to products sold as clear primers, I added a selection of matt mediums as well as rabbit skin glue, for a total of 11 products to test. You can read about the terms \u2018size\u2019, \u2018ground\u2019, \u2018gesso\u2019 and \u2018primer\u2019 in Size, Primer, Gesso and Ground Explained.<\/a><\/p>\n I didn\u2019t test PVA because most artists choose to use it to save money, so they would be using the cheap stuff. Artist grade PVA is not a cheaper alternative to clear primer. There are over 50 different types of formulations of PVA (Polyvinyl Acetate) and only a few are of a good enough quality to make permanent paintings because they have low acidity, retain flexibility, and have low colour change. PVA not made specifically for artists will deteriorate – yellowing, clouding, shrinking and peeling – and is to be avoided if you want your paintings to remain in good condition.<\/p>\n Colour when applying<\/strong> – is it clear or milky so you can see where you\u2019ve done.<\/p>\n Viscosity<\/strong> – is it the thickness of cream, honey, or yoghurt. And a.) does thicker mean that it will fill in the open weave of linen better, b.) will more fluid be smoother with less noticeable brush marks, c.) will more fluid cover more surface area.<\/p>\n Flow<\/strong> – how far does the same amount of primer go on wood and on canvas.<\/p>\n Thinning with water<\/strong> – do they need to be thinned and how much.<\/p>\n Self levelling<\/strong> – do brushmarks smooth out when left.<\/p>\n Sanding<\/strong> – can it be sanded for maximum smoothness.<\/p>\n Shrinkage<\/strong> – does it crack as it dries if you put it on thickly.<\/p>\n Touch-dry drying time<\/strong> – time to be touch-dry for applying a second or third coat. All acrylic primers need to cure for 48 hours before being painted on.<\/p>\n Odour<\/strong> – some people complain of strong smells of some primers.<\/p>\n Ease of use of container<\/strong> – bag, bucket, bottle – and what keeps the gesso from drying around the rim so the next time you use it, it isn’t full of crumbs you have to pick out.<\/p>\n Value<\/strong> – comparing price per 100 ml for good coverage – how far does it go, how many coats are needed.<\/p>\n Transparency<\/strong> – how clear is it over brown linen and a wooden panel. Is it more transparent if applied in 3 thin layers rather than one thick one.<\/li>\n Colour change of surface<\/strong> – does it darken or lighten the wood or linen.<\/li>\n Flexibility<\/strong> – does it crack when you roll the canvas for storage or when you re-stretch it, so it should only be used on a rigid surface.<\/li>\n Texture<\/strong> – chalky, gritty, smooth, silky, plasticky, slick. And one is available in a selection of textures: smooth, medium, coarse, very coarse.<\/li>\n Sheen<\/strong> – is it matt, satin, or gloss when dried.<\/li>\n Absorbency<\/strong> – a.) can you wipe off oil paint or does it stain. b.) does the brush drag or slide smoothly. c.) does oil paint dry matt because the oil has been sucked up. d.) does non-absorbent mean worse paint adhesion of the paint to the primer.<\/li>\n Adhesion<\/strong> – 2 kinds a.) does the primer stick well to the substrate – on wood and on canvas. b.) does dried paint stick well to the primer.<\/li>\n Oil paint penetration<\/strong> – does the primer seal the canvas or does oil paint penetrate through to the back, both thick oil and a fluid oil wash.<\/li>\n Yellowing<\/strong> – does the polymer yellow over time – sometimes acrylic gels do, lots of PVAs do, I let it age for five months in the dark because I\u2019m judging the colour from the rolled up linen I used to test flexibility.<\/li>\n<\/ul>\n I have given them each a number and when talking about different attributes, I use the number for efficiency. At the bottom of the article, each primer is listed individually with all of all its attributes.<\/p>\n 1.<\/strong> Jackson\u2019s Acrylic Fluid Gloss Medium<\/p>\n 2.<\/strong> Jackson\u2019s Acrylic Fluid Matt Medium<\/p>\n 3.<\/strong> Schmincke Transparent Primer<\/p>\n 4.<\/strong> Golden Matte Medium<\/p>\n 5.<\/strong> Golden Fluid Matte Medium<\/p>\n 6.<\/strong> Liquitex Professional Clear Gesso<\/p>\n 7.<\/strong> Winsor & Newton Artists Acrylic Clear Gesso<\/p>\n 8.<\/strong> Holbein Clear Acrylic Gesso – L (Coarse texture), also available in M (Medium texture)<\/p>\n 9.<\/strong> Lascaux Sirius Acrylic Medium Matt<\/p>\n 10.<\/strong> Michael Harding Non-Absorbent Acrylic Primer, Clear<\/p>\n 11.<\/strong> Handover Rabbit Skin Glue – 12:1 dilution<\/p>\n Unless you have special requirements, you usually want to choose a primer that is somewhere in the middle of the spectrum between completely non-absorbent (feels like you\u2019re painting on wet glass, so slick that it won\u2019t grab the paint off of the brush) and the other extreme of too absorbent (feels like painting on masonry, so absorbent that it won\u2019t spread easily and that the oil is sucked out of the paint and it is left without enough binder). You want it slick enough that it has some wipeability and absorbent enough for good adhesion. Some people prefer a less absorbent surface (smoother and more sealed) because of the ease of brush movement or because they wipe back, using subtraction a lot as part of their process, and some like a very absorbent surface because they like their brush to feel like it is sticking and dragging the surface more and is less slick, where the surface grabs the paint from the brush. Of the absorbent surfaces, texture can vary from feeling a bit chalky, to feeling like sandpaper. Sometimes not absorbent can mean poor adhesion, but none of these 11 primers had that problem. Some artists like a tacky surface like primer 1 & 2 or one like RSG where the paint sinks into the ground and feels like it merges with it. None feel chalky. And even when they seem like they are super absorbent, none feel like they are wicking oil away as can happen with some regular gessoes. <\/p>\n I was surprised by how useful a little bit of sanding was:<\/p>\n I used a sanding sponge with a medium fine grit and did the 20 strokes in all directions. The unprimed linen next to the test patch, when sanded, became very white. I think it might be the linen fibres that poke above the primer that is what is being sanded white. The linen might be coated in starch or something similar, I didn’t wash\/rinse\/wet the linen (I’ve heard of some artists that do). Some artists sand their linen canvases between all the layers of white gesso, because it is hairy and the hairs poke up in a more obvious way after they\u2019ve been wetted. Even a light sanding can really improve the surface.<\/p>\n The benefits of a second coat of primer on stretched linen:<\/p>\n There was a big difference between the amount of primer need for the wooden panel and the stretched linen. 1 ml of primer gave a thick coat in a 7.5 cm square on the wooden panel. But it took 2.5 ml to give even a thin coat to the same size square of linen. This is because as you work the primer into the fibres to coat them, lots gets pushed to the back, and it also tries to fill up the spaces in the weave, so it takes more than twice as much primer for linen as for wood.<\/p>\n I checked the odour because some people complain of the strong smells of some primers. These were all mild or had a medium-mild odour. None have a strong or noticeable odour. This includes the rabbit skin glue. See Rabbit Skin Glue: Preparation, Uses And Alternatives<\/a> to read more about the myth of the odour of RSG.<\/p>\n Mild = 1, 2, 6, 8, 10 and 11. All acrylic primers need to cure for 48 hours, but if they become touch-dry quickly, you can do a second coat sooner and then leave it for the 48 hours. If they dry too fast you may not be able to spread it well or get it into the weave by brushing in all directions. None of these dried too fast. I applied a thin layer to stretched linen canvas and timed them until they were touch-dry.<\/p>\n The four with lots of thick creamy texture poking through to the back were the slowest to dry, except Golden Matt Medium which formed enough of a skin to not be wet on top so you could do a second coat sooner. Even with loads of brushing in all directions, the first layer wasn\u2019t very even on some of the primers so you may need a second coat to make sure you don’t have streaky coverage.<\/p>\n This is the touch drying time of the first coat to allow applying of a second coat, if you want to.<\/p>\n 1h = 1, 2, 3, 11 I painted out long stripes of each on a sheet of linen and then rolled it up tightly and left it for 5 months. When I unrolled it none of them cracked with the flattening out. Number 1 stuck to itself a bit, because it is tacky, and number 2 stuck to itself just slightly.<\/p>\n The primers come in a variety of formats and sizes: bottles, pots, a pouch and dry granules that you need to mix with water and warm up. Like white gesso, any container where the primer can dry out on the upper walls inside or in the threads of the container, can create dried chunks that have to be picked out of the surface. The formats that are least likely to have this problem are the squeeze bottles and the pouch – those are the ones with small openings and less drying out that occurs. And the squeeze bottles are just really tidy and convenient.<\/p>\n It probably needs a longer time to test for yellowing because it happens slowly in acrylic. But looking at the colours over five months, none changed noticeably.<\/p>\n Some colours of primer are easier to see as you apply them, to get a good coverage.<\/p>\n One coat on linen- Two Coats on Linen-<\/p>\n 1 – One coat = semi gloss, 2 coats = gloss and slightly darker 1.<\/strong> One coat: semi gloss, some darkening. Two coats: very glossy, shows brush marks, not darker than one coat, but is then a tacky surface texture.<\/p>\n 2.<\/strong> One coat: matt, some darkening. Two coats: semi gloss, no brush marks, same darkness as one coat, very smooth.<\/p>\n 3.<\/strong> One coat: very clear, invisible. No change with second coat.<\/p>\n 4.<\/strong> One coat: clear and darkening. Two coat: slightly smoother, slightly more absorbent.<\/p>\n 5.<\/strong> One coat: clear nearly invisible. Two coats: sightly smoother, more absorbent. Lovely finish.<\/p>\n 6.<\/strong> One coat: clear, nearly invisible. Two coats: same as one coat, very gritty and absorbent.<\/p>\n 7.<\/strong> One coat: clear, nearly invisible. Two coats: same as one coat, very gritty and absorbent.<\/p>\n 8.<\/strong> One coat: clear, nearly invisible. Two coats: rougher and cloudier.<\/p>\n 9.<\/strong> One coat: whiter. Two coats: rougher and even whiter.<\/p>\n 10.<\/strong> One coat: clear, nearly invisible, slight darkening. Two coats: no different from one coat.<\/p>\n 11.<\/strong> One coat: clear, slightly darkening. Two coats: semi-gloss, rougher<\/p>\n Testing using clear primer as size to stiffen the canvas for less wobbling:<\/p>\n Not at all, the least stiff, very soft: 10. All primers on panels in one and two coats, were absorbent enough for the thicker oil mixture to dry matt or semi-matt, except 4, 5, 11. On linen, the oil remained the shiniest on 11, even though it is the least wipeable so most absorbent. The rest all dried semi-gloss. Number 5 was the next most glossy.<\/p>\n The primers for the oil penetration tests on the stretched linen have one coat of 2.5 ml of primer in a 7cm square of linen, brushed well in both directions so it pushes some to the reverse side of the linen. All have a second coat of 1 ml on the lower half of the square. The second coat didn’t push through to the back because it was already pretty sealed. It was left to cure for 48hrs before testing oil paint.<\/p>\n These photos show the back of the canvas while the primer is wet. Each one pushed through to the back a different amount. This is just to give you an idea of how it handles when you are applying it, and to show they are different. <\/p>\n They were all pourable. The more fluid primers (1, 2, 3, 5, 11) were fast to brush out, as was the thickest (number 10), the rest took a lot more brushing to coax out to cover the same amount of panel. Using a damp brush helped with number 7. Number 10 says to ‘Shake Well’, which produces lots of bubbles, but they brush out. It is the only one that lightens the wood, rather than darkens it. Would probably be invisible on cotton canvas. It is also sticky like honey.<\/p>\n For both linen and panel, I brushed on two thickness of oil paint – an oil wash and a thicker oil mixture. The oil paint mixture I used for testing is Jackson\u2019s Artist Oil Phthalo Blue with Jackson\u2019s Fast-drying Medium Gloss and a little Gamsol to create a medium-heavy consistency. The thin wash mixture has a lot more Gamsol.<\/p>\n All primers add a gritty feel to the smoothly polished wood surface, except 1, 2 and 5. The results of testing oil paint on a wooden panel with two coats of primer are listed under each primer. All bled at least a little into the wood grain, except number 6, so if you don’t want that then you will need at least three coats for the rest of them. I also did the same test on an area of unprimed wood – as expected, the paint bled\/feathered and left an oil halo, and both thicknesses of paint stained and couldn’t be wiped away at all. Number 6 and 7 were so absorbent that they were almost as hard to wipe away as the unprimed area.<\/p>\n 1.<\/strong> Paint was smooth and slick on just one coat of primer, good wiping.<\/p>\n 2.<\/strong> Paint was smooth and slick on two coats of primer, even better with three. Good wiping. No brush drag or grittiness.<\/p>\n 3.<\/strong> Benefits from three coats. Good wiping. No brush drag or grittiness.<\/p>\n 4.<\/strong> I could distinctly feel the weave of the canvas. Benefits from three coats. Good wiping. No brush drag or grittiness.<\/p>\n 5.<\/strong> One coat was staining. Sealed well at two coats. Third not an improvement. Not gritty. Wiped away well.<\/p>\n 6.<\/strong> One and two coats are staining and with third coat still unable to wipe away much. Very absorbent, has brush drag.<\/p>\n 7.<\/strong> Left little white balls that had to be picked and brushed off the surface before testing the paint. There was some wipe away possible with three coats. Gritty and very absorbent, similar to number 6.<\/p>\n 8.<\/strong> Each layer becomes more sealed. 3 coats is very absorbent but with some wipe away. Gritty, not slick.<\/p>\n 9.<\/strong> Heavy oil paint skips over the weave. Very absorbent at three coats and becomes a bit more sealed feeling, but never wipes away. Gritty.<\/p>\n 10.<\/strong> Sealed at two coats, not great wipe off but better wipe-off at three. Not gritty, not too slick.<\/p>\n 11.<\/strong> Very absorbent and staining until more than 4 coats. After that it becomes smoother but still pretty absorbent. Uniquely, it has tiny sparkles on the surface.<\/p>\n Four of the primers sealed the canvas enough with one coat that there was no oil penetration through the canvas (primers 2, 3, 4, and 10). The other seven ranged from very slight penetration to a moderate amount. They all were sealed perfectly after a second coat. I also show an example of the oil halo you get on unprimed linen.<\/p>\n 1. Jackson\u2019s Acrylic Fluid Gloss Medium<\/a><\/strong> 2. Jackson\u2019s Acrylic Fluid Matt Medium<\/a><\/strong> 3. Schmincke Transparent Primer<\/a><\/strong> 4. Golden Matte Medium<\/a><\/strong> 5. Golden Fluid Matte Medium<\/a><\/strong> 6. Liquitex Professional Clear Gesso<\/a><\/strong> 7. Winsor & Newton Artists Acrylic Clear Gesso<\/a><\/strong> 8. Holbein Clear Acrylic Gesso<\/a> – L (Coarse texture), also available in M (Medium texture)<\/strong><\/a><\/p>\n<\/a>Things I Wanted to Know About the Application of Each Primer<\/h2>\n
Things I Wanted to Know About the Physical Characteristics of Each Primer<\/h2>\n
<\/a><\/p>\nThe 11 Clear Primers<\/h2>\n
Absorbency<\/h2>\n
<\/a><\/a><\/a>Sanding<\/h2>\n
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<\/a><\/a>How Many Coats of Primer You Need<\/h2>\n
\n
Odour<\/h2>\n
\nMedium = 3, 4, 5, 7, 9.<\/p>\nDrying Time<\/h2>\n
\n2h = 5, 8
\n2.5h = 4, 10
\n3+ = 6, 7, 9<\/p>\nFlexibility<\/h2>\n
<\/a><\/p>\n<\/a><\/p>\nFormats Available<\/h2>\n
Yellowing<\/h2>\n
Wet Primers on Linen<\/h2>\n
<\/a><\/p>\nColour Change and Transparency<\/h2>\n
Dried Colour on Linen<\/h2>\n
<\/a>Colour and Transparency of Primer on Linen<\/h2>\n
\nMost invisible: 3, 6, 7, 8.
\nNext most invisible: 5 & 10.
\nNext most invisible: 2 & 4.
\nNext most invisible is 1.
\nDarkest is 11.
\n9 is much lighter, like a transparent white wash<\/p>\n<\/a>
\n2, 4, 5, 10 & 11 – Second coat is the same as the first coat
\n3, 6, 7, 8 & 9 – Second coat is whiter
\n11 – 4-6 coats got darker on both linen and panel like the cloth had been wetted.<\/p>\nDried Colour of Clear Primers on Light-coloured Wooden Panel<\/h2>\n
\n
<\/a><\/p>\n<\/a><\/p>\n<\/a>Stiffness<\/h2>\n
\nSome stiffness: 1, 2, 3, 6, 7, 8.
\nA bit stiffer than most: 4 & 5.
\nSecond most stiffest, pretty stiff yet still foldable: 9.
\nThe most stiff, very stiff. Though least able to be creased and folded and bounce back, lost its stiffness on the creased fold: 11.<\/p>\n<\/a><\/a>Observing the Absorbency of the Primers by How Matt the Paint Became<\/h2>\n
Brushing onto Stretched Linen<\/h2>\n
<\/a><\/a><\/a><\/a>Brushing Onto Wooden Panel<\/h2>\n
<\/a><\/p>\nTesting Oil Paint in Two Thicknesses (a Wash and Thick Body) on Linen and on Wooden Panel<\/h2>\n
Oil Paint on Primed Wood<\/h2>\n
<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\nOil Paint on Primed Linen<\/h2>\n
Oil Paint Penetration to the Back of Clear Primed Stretched Linen Canvas<\/h2>\n
\nThe Attributes of the 11 Clear Primers<\/h2>\n
<\/a>
1. Jackson\u2019s Acrylic Fluid Gloss Medium
2. Jackson\u2019s Acrylic Fluid Matt Medium
3. Schmincke Transparent Primer
4. Golden Matte Medium
5. Golden Fluid Matte Medium
6. Liquitex Professional Clear Gesso
7. Winsor & Newton Artists Acrylic Clear Gesso
8. Holbein Clear Acrylic Gesso – L (Coarse texture)
9. Lascaux Sirius Acrylic Medium Matt
10. Michael Harding Non-Absorbent Acrylic Primer, Clear
11. Handover Rabbit Skin Glue – 12:1 dilution<\/figcaption><\/figure>\n
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