Friday, September 9, 2011

Preparing a Linen Canvas: How To

I've been getting a lot of e-mails lately asking me how I prepare a linen canvas, and also why I prefer it over cotton canvas. So, from now on I hope to simply refer these requests to this blog post. Hopefully this helps! If you are gluing linen to panel, that is a different thing. For our purposes today, I am referring to stretching, sizing, and priming a linen canvas on stretcher bars, not panel.

My reasons for using linen: linen is very different from canvas, not only in its texture and weave, but also in the way it is prepared and how it feels to paint on. Linen is much smoother, especially if prepared properly with a size such as rabbit skin glue or PVA glue, and an oil-based gesso rather than acrylic. The oil primer really makes for a smooth working surface, whereas acrylic gesso tends to "eat up" your oil paint during the first several working layers, causing the paint to lose its luster. This can be very frustrating. Although linen is generally much more expensive than canvas, I don't think I could ever go back to canvas. Once you've tried it, you'll realize too that there's no going back!

PREPARING A LINEN CANVAS FOR OIL PAINTING – STEP BY STEP
by Anna Rose Bain

SUPPLIES
  •           Linen:  Many artists purchase pre-primed linen, but I always buy mine raw. I find that being able to stretch and size my linen is much easier and produces better results if I do it all from scratch.  I’ve tried many different kinds, but my favorite linen to work with is Claessens portrait linen. Linen can be expensive, so make sure you look for an online coupon code before you buy! 
  •           Stretcher bars: You can get stretcher bars of any length through just about any art supply store or website. I often buy them from Hobby Lobby, but my favorite stretcher bars for heavier-duty, larger canvases, are from Utrecht. For any canvas bigger than 24x36, I recommend using a cross brace, attached with T-bars.
  •           Double boiler
  •           Plastic drop cloth or garbage bags
  •           Sizing: There are a number of excellent options on the market, including PVA size, and acrylic polymers such as GAC 400/GAC 100 from Golden. My product of choice is good old traditional standard, rabbit skin glue. I know, it sounds cruel – it IS actually made from rabbit collagen… but this method has been tried and true for centuries. Not only is it is the best coating to protect a canvas from the linseed oils in paint (which would naturally destroy canvas fibers over time), but it also makes the canvas so tight that you can pluck it like a drum. You can purchase rabbit skin glue from Daniel Smith or Utrecht. It comes in powder form.
  •          Scissors
  •          Marker or charcoal pencil
  •          Stapler: I have a couple that I purchased from Hobby Lobby in the canvas/painting department. They are called “EasyTackers” and call for No. 3 or Arrow JT-21 staples.
  •           Rubber mallet
  •           Measuring Square
  •           Fine grain sandpaper
  •           Gesso brushes (one for the rabbit skin glue, and one for priming). They should have soft bristles and be fairly large, at least 3 inches wide. For sizing, you may also use a sponge instead.
  •           Oil primer: I use Gamblin's oil painting ground (formulated with alkyd). Lately I have also started using lead ground, which is extremely pleasurable to paint on but requires at least 3 months to cure (and I'm just not that patient!).
  •           Bucket
  •           Putty knife
  •           Odorless mineral spirits
  •           Paper towels
  •           Wood paint stick or stirring rod for mixing


DIRECTIONS:

STRETCHING:
1) Assemble your stretcher bars, using the square to make sure they are straight.
2) Line up the stretcher bars with your linen on the floor; using a straight edge and a marker or charcoal pencil, draw a line around the stretcher bars on the linen, measuring about 1.5”-2” all the way around your stretcher bars, depending on how thick they are.
3) Cut the linen to size.
4) With the canvas still face down on the floor, staple the linen to your stretcher bars, starting with one staple in the middle of each side. If you intend to size with RSG, leave a good amount of slack in the middle. This is different than stretching a cotton canvas, where you stretch it as tight as you can. However, if you plan to size with PVA or GAC-100, make sure you DO tighten the linen as much as possible. In my experience, acrylic polymers are not as effective for tightening your canvas, so you must plan ahead, knowing which size you'll be using.
5) Continue to staple outwards towards the corners, pulling the linen evenly and out from the center before each staple, and working all the way around rather than one side at a time.
6) Once you’ve reached the corners, fold them around neatly (see my YouTube video below) and staple them secure.


7) When the linen has been stapled on completely, brush any lint, specks, or hairs off the front of the canvas before moving on. If you have pets in your studio, this can be a problem to watch out for! If you are sizing with acrylic polymer, wipe the linen gently with a damp rag, and allow it to dry. This will give you some of the extra tightness you need.

This is a what a neatly folded corner should look like

SIZING:
1) Lay your canvas out on a plastic drop cloth, on a flat surface
2) If you are using PVA or acrylic polymer (instructions for GAC-400 and GAC-100 can be found on Golden's website here. They recommend one coat of GAC-400 followed by one coat of GAC-100 for adequate protection), skip ahead to stage 4.
Using a double boiler on the stove, prepare rabbit skin glue according to directions. Some directions require you to soak the RSG overnight, others don’t. I’ve tried both and found that as long as the mixture has had enough time to dissolve, whether overnight or on the stovetop, it still produces great results. Keep the burner on low, never allowing the mixture to boil. It should be heating for at least 30 minutes before it’s ready to use.
3) When rabbit skin glue is completely dissolved and nice and warm (but not boiling hot), take the pan off of the boiler and prepare to brush the mixture onto your prepared canvas. 
4) Using a 3-inch gesso brush, apply the glue generously to your canvas, starting in the very middle and working your way out. Make sure to brush onto the sides as well. You will instantly see the canvas begin to tighten. Sometimes I use a sponge instead of a brush (you’ll want to wear rubber gloves if you do it this way!).
5) Allow canvas to dry several hours or overnight. If the canvas starts to warp because it’s been stretched too tightly, hold down opposite corners with weighted objects.
6) When dry, lightly sand canvas.
7) Apply a second coat of sizing. Leftover rabbit skin glue can be re-heated, but make sure you use it up within no more than a day or two, as it can go bad after a while.

Linen canvases still wet from first coat of RSG

PRIMING:
1) Keep your prepared canvas on the plastic drop cloth.
2) Put about 4 parts oil ground and 1 part odorless mineral spirits in your mixing bucket, and stir with a mixing stick or plastic utensil (something disposable). It should be a smooth consistency but not runny. If you are using alkyd oil-based primer, you can skip mixing in the mineral spirits and go straight to step 3.
3) Using your putty knife, apply the oil ground in thin, smooth strokes across the top of your canvas, working from top to bottom in one direction (as opposed to from the middle outwards, like the glue).
4) Smooth your knife strokes with your gesso brush, also moving in one direction. Make sure you prime the sides of your canvas as well.
5) Allow first coat to dry. When dry to the touch, lightly sand your canvas, wipe the surface with a slightly damp, lint-free rag, and then apply a second coat of oil ground, this time brushing it perpendicularly to the direction you applied it before.
6) Allow this second coat to dry. If desired, a third coat may be added, but usually two coats are fine. Because of the alkyd component, Gamblin states on their website that their oil ground only needs 7-10 days to dry before it's ready to paint on. I've found that it needs more like 3-4 weeks, otherwise the second coat will still have some tacky/sticky spots. Lead ground, which can be applied in the same manner as the oil ground (with the exception of sanding), takes 3-6 months to fully dry.
7) Before painting, do the "fingernail test." If you poke the canvas gently with your fingernail and it leaves a mark, it's not cured enough to work on. 
8) Happy painting!




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12 comments:

  1. Hello Anna

    I have a whole whack of bleached white linen ranging in size from 2.5m x 2.5m to 1.5m x 3m. I would really like to turn these into artist canvases. Can you give me any advice?

    Thanks

    Felicity

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  2. Could you please tell me what you do different when adhering raw linen on panel?
    Thanks,
    Darryl Nelson, BC Canada, dnelson700@hotmail.com

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  3. Would love to see photos with this. I need to venture into this.

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  4. Tried this and the center of my linen was warped and sagged, almost as if it had been dented. I felt as if I stretched it uniformly, and the rest of the surface was nice and tight. Any ideas why that would happen?

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  5. Meg, sorry to hear that! It could be the type of linen you used. The finer the linen, the more likely it will warp or bubble. Try putting another coat of rabbit skin glue, and if it's still sagging, you might need to use corner braces to tighten it on the stretcher bars. Hope this helps!

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  6. How do you get the RSG out of your brush?

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    Replies
    1. Hi Lindsay - you can use soap and warm water to clean your RSG brush; the brush you use for the primer will have to be cleaned with turpentine or mineral spirits and/or a linseed oil soap.

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  10. Thanks for the great information! I’ve always stretched my cotton canvases and I’m looking forward to making the step up. ��

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  11. Hi! How much slack should I leave? SHould it be just less than too tight? I intend to use rsg on linen

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