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How can I get rid of the spots on the back of an older painting?

These are called "climatic stains" and can be very annoying, especially if you want to sell the painting.  (They do not affect the quality of the painted surface, they're just unsightly.)  Here's a good way to get rid of at least most of them:

1.  Dampen a sponge in a solution of 1 CAP FULL of bleach to 1 gallon of water.  Wring out the sponge and apply lightly to the back of the canvas. (Discard the remainder.)  Note: it is very important not to use too much, as drenching the back of a painting will loosen the paint and primer.

2.  Let dry.

3.   To neutralize, use 2 Tablespoons of baking soda to 1 pint of water and sponge on lightly.  (Discard the unused portion.)  Note: In rare instances, stains may also appear on the top surface of an unpainted canvas. I would use the same method (although not at the same time as doing the back of the canvas), and follow with a fresh coat of gesso just in case the spots migrated from the back through holes in the original priming.

How can I clean dried acrylic paint from my brushes?

Almost any drugstore alcohol does a good job on synthetic brushes, but can ruin natural bristle brushes. (Synthetic brushes are better for acrylic painting anyway as the bristles won't get waterlogged.)  Just soak a few minutes and then follow with a soap and water wash.  (You can also use alcohol to lift paint from your paintings.)

I have an oil painting that became torn in moving. I've done a conservative repair patch with light weight cotton and canvas fabric "cement" glue but I'm not satisfied with the way the fibers came together repairing it from the back. Do you have any expert advice? Please also give me some pointers on matching the "sky" color which is a solid turquoise. This painting was exposed to dirt and smoke and I tried to clean it using warm soapy water and then clear water. THANK YOU

There are really three separate issues here, the tear, matching the color, and cleaning the painting.

1. Mending the tear:  first, I hope that the "fabric cement" you used won't stain or damage the canvas. Always check these products and make sure they are meant for use on paintings and won't damage them. A good glue to use on unpainted canvas is acrylic gel medium. If you were starting from scratch to mend the tear, I would start by taking some threads torn from a piece of canvas and, working from the back, set them into any gap in the tear, brushing the gel medium over on the back of the mend only. Then check the front. If it looks okay, let it dry and then use the thin piece of cotton, securing with the gel medium. (One of the advantages of using the gel medium is that it is water-based and when it dries it will tighten the edges of the tear.) I have used this method successfully (minus the addition of the piece of cotton) to fix a cut in a painting left by a careless framer. Of course a tear can cause more damage to the edges of the hole than a knife cut, so the mend may not be as successful. Note: be sure any fabric you use to cover your mend is thin, because canvas and thick cloth patches will cause a bump in the front surface of the painting that is easily visible. In the case in question, the cotton has already been glued to the back so that any repairs must be made from the front (if the cotton can easily be removed it would probably be best to do so and continue to repair from the back.) It is very hard to advise you without seeing the extent of the damage still visible, but I will do my best. Does the tear need more threads to fill it up? If so, use a small brush to put a little bit of the gel medium only where you are going to set in the new threads and then press in the threads (tweezers are helpful) and let dry. After you have mended the tear, you will need to paint over the damaged area on the front of the painting. If you are going to use oil paint, you should first dab on a little acrylic gesso onto any exposed threads in the tear to protect them from the oil paint. Pressing any loose fibers into the wet gesso will help smooth the surface. Let this dry.

2.  Painting the tear: You say the tear is in an area of sky that is a solid turquoise. Accept the fact that you probably will not be able to exactly match the turquoise, but it can be painted in a swish of color that will look like a natural part of the sky even if it doesn't match perfectly. In order to do this, you must repaint the area around the tear so that the new color can be extended in a natural way. If the painting has been varnished, give the area around the damage a light wipe of gum turpentine to soften the varnish. If the mend is too obvious for this then I would suggest adding a cloud or other feature that would allow you to add a thicker layer of paint to conceal the mend.

3.      Cleaning the painting: I know you didn't ask about this, but I'm concerned with the method you used to clean this painting. I truly hope you didn't use too much water as you could have seriously damaged the paint layer and could cause it to separate from the canvas. A better idea would have been to use the inside of a fresh loaf of unsliced bakery bread, gently dabbing or pressing at the painting, and changing the bread as it gets dirty. Valuable paintings should always be cleaned professionally.

How do I approach painting something like weathered wood that has one color visible under another? Do I lay down the darker color and then add the lighter, or put down a middle tone and come back and add darker & lighter grain?

Here's a good way to approach a layered color or marks of one color over another color. (This could be clouds against a sunset sky, red streaks on a yellow apple, or even speckles on a fish or weathered wood.) Try to discern which color predominates in each section you are painting and put that down first in a solid but thin layer (very little medium). Then for the contrasting color, decide whether you want to slightly blur the edges or whether you want them sharply defined (or scratchy looking). For blurred, put the top patterning on while the undercoat is still wet and use a hake or blending brush to gently blend. In the case of weathered wood you might see some blurred areas of patterning of the wood grain; these you would do wet into wet and then let it dry before applying a more sharply defined layer in a dry-brush technique.

If you are painting a layered color object, try to determine what color is underneath or seeming to be a background for the rest and put that down first. The under layer may shade from one tone or color to another--just paint it as you see it. Try to mentally subtract what comes on top. (Same process for sunsets, etc. Subtract the clouds, paint the sky, add the clouds on top.)

Can I add some color to gesso to tint my canvas before starting my painting? I’m going to be painting gray rocks so I was thinking of tinting the gesso gray.

First of all, I think it’s a very good idea to buy some acrylic gesso and give a new canvas an additional coat of priming before starting a painting. I’ve noticed that many of the canvases that are commercially prepared these days have very poor priming and the paint does not go on right.

Now to your question. If you are going to paint gray things, I wouldn't tint the primer with gray but rather with a warm color. In other words, use a "counter color", one that will add more interest to your final choice of colors. Here's an example: if you are painting a lot of gray rocks that are cool in overall hue, I would use a warm tint underneath: Raw Sienna, Burnt Sienna, or even orange or red. These colors which are "counter" or in opposition to your final layer will add richness and interest to your final color. Just be sure to keep the priming color light. And do look at artists like Winslow Homer or some of the American Impressionists to see how many colors they used in painting rocks beyond just a flat gray.

To add color to the gesso, just add a small amount of the desired acrylic color and mix thoroughly.

I keep getting books that require me to go out and buy more paint colors. Can’t I mix these colors from the colors I have?

If there is a color that is recommended or that you think you may want, go to the art supply store and find a tube of the color. Look at it closely. Somewhere on the tube it should give you the component pigments that make up the color. Often, there will be only one pigment listed because the color comes directly from the mineral or chemical and is not mixed with another color. Example: Grumbacher's Thalo Blue on the back says Pigment: Copper Phthalocyanine (Thalo)--nothing mixed here. But Liquitex's Turquoise Green says Pigment: Phalocyanine Green (PG7), Phthalocyanine Blue (PB 15), Titanium Dioxide (Titanium White) (PW6), Zinc Oxide (Zinc White) (PW4). From this you know the color is mixed from Thalo Green, Thalo Blue, and white. (The letters and numbers are scientific designations--unfortunately, some brands JUST give you these scientific tags, but with some thought you can figure out what the letters stand for; forget about the numbers.) Then it's just up to you to decide whether it will be worth it to you to have that particular color premixed in the tube or to mix it yourself. (It may take some experimentation to get the right proportion of one color to another.)

Most lists of paint colors recommended for the basic painter’s palette do not have the same colors that students remember from their coloring days. Instead, these pigments are used to mix common or color wheel colors. Beginning painters look for the colors they are familiar with, and so companies sometimes put out their versions of these colors with the company name attached (i.e. Winsor Red) These colors can usually be mixed easily with common pigments (see my book), but are sometimes worth buying. For instance, a proprietary red such as Winsor Red is brighter than one you could mix, but Winsor Yellow can easily be matched by taking a “cool” yellow such as a Lemon or Cad. Yellow Lt. and mixing a little “warm” yellow such as Cad. Yellow Medium into it.

Can I speed the drying of my oil painting by putting it in the sun or using a hair dryer?

NOT a good idea, either way. Remember that your oil paint dries from the top down and becomes more brittle as it dries. If you try to rush the drying, the paint may crack.

I have masked off a portion of my oil painting to get a clean edge. Should I wait until the paint is dry before I pull it off?

Whether you are working with oil or acrylic, I think it’s best to pull the tape while the painting is still wet. Often it doesn’t seem to matter, but sometimes, especially with acrylics (but also with oil occasionally), the paint on the tape bonds with the paint on the canvas, and when you pull off the tape pieces of the paint peel off the painting as well.

Note to acrylic artists:  You may want to look into "Frog Tape", a new painters tape that seals itself at the edges when a water based paint hits it.  Sounds great!

Some artists use walnut or any other vegetable oil for cleaning brushes while oil painting to avoid solvent fumes. Do you recommend using the "Turpenoid Natural" as a better alternative—and just make sure that you wipe as much of it from the brush so as not to effect the drying paint film? I love oil painting but the solvent fumes from constantly cleaning my brushes is rather unpleasant.

I don't think I would use vegetable oil, but I might use walnut oil that is made for oil painters' use and with that painting system.  Traces of oils not made for artists' use will get into your painting and I don't know what long term effects this could have. In addition,  these oils don't wash out easily and may build up and dry into the bristles of your brushes, especially if you don't paint every day.

One of the reasons I like Turpenoid Natural so much is that it is water soluble, so it grabs the paint out of your brush and then it washes it away, leaving no residue in your brushes to harden and actually conditioning the brush. And any traces that remain are not harmful to your painting, so it isn't necessary to worry about getting the last bit out of your brush while painting. It is not petroleum based, so although there is a slight odor, it isn't the strong smell of other cleaners. By the way, this stuff is much more absorbant than the solvents you're used to—no need to keep a big can of smelly solvent around while painting. I use about a half-inch in a small can for a painting session. It cleans your brush even when it looks really dirty.

An update on Liquin

Since I continue to get questions on the use of Liquin, I decided to go straight to the source and contacted a tech expert at Winsor & Newton. Here is her reply to my questions about its use as a paint medium and when to varnish:

We do not recommend applying a medium free paint layer over a liquin layer. Doing so would violate the "fat over lean" or "more flexible layers over less flexible layers" rule of oil painting, and could lead to cracking in your paint layer. Liquin added to a paint layer will increase the flexibility upon drying of the layer (making the layer "fatter")- a paint layer with no medium in it would be less flexible ("leaner").

This validates my misgivings about using Liquin as your painting medium (unless you don’t mind making sure you always add the same amount of medium or even more medium in every layer of paint you apply, and never use paint right out of the tube over paint combined with Liquin.) While you always have to be mindful of “fat over lean”, it is far easier to deal with using a simple medium.

We recommend waiting 6-12 months before varnishing a painting, even one in which you have used liquin as your medium. Liquin speeds the touch dry time of the paint film, but the paint still needs 6-12 months to oxidize (dry to a stable film) before it can be safely varnished.

A further update on Liquin

My main concern with this product has always been the hazard of combining paint out of the tube with paint mixed with the fast-drying Liquin.  I have solved this problem by combining Res-n-gel medium (which speeds drying and adds gloss without thinning the paint) with all of the paint daubs on my palette (about 1:3) and adding Liquin as needed to thin the paint.  These both contain alkyd resins.  I have found that this method allows me to paint on top of dry paint the next day AND it is much easier to get an even shine!  Note: the makers of Res-n-Gel (Weber) recommend thinning with regular medium or paint thinner which will make the drying time longer.

Good to know.

I bought a great frame in a thrift store but when I brought it home I realized that the liner was discolored. Is the frame a loss?

NO. Liners (the linen inset in a frame that is right against the painting and inside the actual frame) frequently get discolored with age. It can be expensive to replace them but there is a better solution: paint the liner with acrylic paint. Here's how. Wipe the liner clean with a damp rag and then carefully tape off the frame above the liner, making sure the tape comes right down to the liner. Start with white acrylic paint in a small wide container (like a tuna fish can). Be sure to have enough to cover the whole liner. Add a small amount of acrylic Burnt Umber and Yellow Ochre to the white and mix thoroughly to match the color of the linen. Then just paint it on! Your liner should look clean and fresh and stay that way.

I just finished a small painting in oil using Liquin and mineral spirits as my medium. The painting appears to be dry, even though I finished it only two days ago. I thought I might try either retouch varnish or Winsor and Newton Griffin Picture Varnish on the painting to give it a bit of shine. I need it to be dryfor exhibit in nineteen days. Which should I use, how soon can I apply it, and will it dry in time?

I would err on the side of caution and use a light coating of retouch varnish. This can be done as soon as the painting is dry to the touch.This will dry quickly.

FYI: Winsor and Newton emphasizes that even though Liquin seems dry, it needs 6-12 months to cure before varnishing.  Remember, oil paint dries from the top down and air needs to get all the way down to dry the bottom layer of paint. I just think it's too soon to even think of varnishing with a picture varnish. You gain little, and you may endanger the painting.

Note: See "An update on Liquin."

Why does my glaze bead up when I try to apply it?

This is a really annoying problem! Basically, there is something in the paint layer that rises to the surface and repels the thin glaze. There are several ways to combat this problem. First, gently blot up the drops of glaze and then spray the area with retouch varnish and reapply the glaze. The stickiness of the varnish will help to grab the glaze. Another method is to gently dab the resistant surface with a soft, lint-free rag dampened with odorless mineral spirits. This should dissolve whatever is causing the resist. Wait two hours for the residue of the spirits to evaporate and then reglaze your surface. It goes without saying that your under layer of paint must be very dry. (Detailed information about glazing can be found on pp. 35, 95-96 of my book "The Oil Painting Course You've Always Wanted."


When you are glazing or oiling out, be sure to frequently check the glaze under a raking (from the side) light to catch sags and drips in the glaze. Once these are set they are difficult or impossibly to remove.

If I don't like part or all of my painting, can I gesso over it and start over?

This question keeps coming up, so even though I've talked about painting over an old painting in a previous question, let's talk about the use of gesso over oil paint.

For those who don't know, gesso is a mixture resembling white tempera paint that is used to prepare canvas or paper to accept paint. (Oil paint will rot unprepared cloth and paper.) Unless you stretch and prime your own canvases, most of the canvas products you use are primed with acrylic gesso. Traditional gesso was made with animal hide glue and chalk (a smelly laborious process) and when it dried was prone to cracking. Modern formulations are made with acrylic medium and white pigment. They are called "acrylic gesso" or just "gesso" and dry to a tough, flexible surface that will accept oil paint as well as acrylic.

To answer your question, acrylic gesso is an excellent primer for oil paint, but it will not adhere well to an oily surface, including an oil painting. Within a short time the gesso will crack away from the painting's surface with disastrous results! For a better way of painting over a painting, see the question dealing with this subject.

I leaned my canvas against something and now I have a dent in it. How can I fix it?

Use a barely damp sponge or cloth to lightly dab at the back of the dent and let it dry. The canvas should tighten up as it dries. Repeat if necessary, but don’t saturate the canvas with water as it could damage the surface of the painting.

Can I start a painting mixing Liquin into my paints so the paint dries fast in the under painting phase, then later paint with linseed oil when I want the paint to dry slow or am I asking for trouble? The same question applies to using Turpenoid with the under painting then moving to linseed oil or some other medium.

First the short answer: It’s not a good idea to mix mediums made from different ingredients. It’s much better to use the same basic ingredients throughout your painting so that you can be sure the whole thing bonds together well. (See question 6 for the exception.)

Liquin is a fast-drying medium that contains an alkyd resin, so its composition is different than a linseed oil-paint thinner medium. Because of the alkyd resin, Liquin layers are more flexible and shouldn’t be used under layers that are more brittle because of the danger of cracking. Oil paint shrinks and gets more brittle as it dries; therefore any paint you put on top has to have at least that amount of Liquin to match the flexibility of the first layer. In most cases this isn’t practical.  (Liquin will work if you add Res-n-Gel (Weber) to all of the paint on your palette --it also speeds drying.)

What does work is to use a standard medium (I recommend 1 part regular Turpenoid* or mineral spirits : 1 part artists linseed oil for common use), and then just use less oil if you want to paint an under layer. It is perfectly valid to use just paint thinner like Turpenoid in the first layer, but I like to add small amount of oil to make the mixture more stable. (Too much Turpenoid will dilute the binding agent in the paint.)

Your paint (unless it's very thick) will dry overnight using just the Turpenoid, with the addition of oil, a little longer. In subsequent layers you can just revert to a 1:1 ratio. Very simple!

*I like regular Turpenoid (in the blue label container) as my paint thinner. I would never use gum turpentine because of its toxicity.

How do I continue painting on top of an old painting?

(It is preferable to attempt this only on an unvarnished painting.) It depends on how long the painting has been dry. If it is very old, it will probably need to be cleaned with a barely damp rag, (follow all damp wipes with a gentle patting dry with a clean rag) and sprayed with retouch varnish. Allow the varnish to dry before the next paint layer is applied. If the painting is very dirty, a little dishwashing detergent can be used in the water on the damp rag and then followed with a plain water wipe and dry and then sprayed with retouch varnish.  (I have also heard of wads of fresh bread being used as an "eraser" to remove dirt.)

Note: be extremely cautious of how much water you use, as it could cause cracking in the paint layer.

Can I reuse an old canvas?

It’s usually not a great idea, but if you must, then be sure you scrape or sand off all of the ridges from old brushwork (place a hand in back of the canvas that you are working on to prevent a scraping knife from cutting the canvas). Giving the canvas an all-over sanding will help it to accept a new layer of paint too. If there are strong contrasts in the values of the paint, you will probably want to paint out contrasting edges with a middle value under-painting.

How should I frame my painting?

Frames need to fit the thickness of the stretcher bars on your painting.  Most traditionally stretched canvases use 3/4” thick stretcher bars (the edges of the painting are 3/4” wide).  There should be a similar inset in the frame for the painting to drop into so that painting and frame fit flush to the wall.  This inset is called a “rabbet”.  Many new canvases are stretched more cheaply on 5/8” stretcher bars and these would also fit into a 3/4” rabbet frame.  Canvases are also available with thicker stretcher bars.  These make for greater stability in the larger size canvases and would need a deeper rabbet if they are framed.  If the rabbet isn’t deep enough, the painting will stick out in the back and the frame won’t lie flat against the wall.

Note: Recently I have noticed that there are a great many frames being made with very shallow rabbets.  The framer then glues kraft paper over the entire back of the painting to conceal the fact that there is a bump in the back where the painting sticks out of the frame. I have been told that this is now “accepted practice” but I have my doubts.

Do you have advice on entering shows?

Be professional. Make sure that the images you are entering, in whatever form (digital, slide, or photo) are well photographed, with even edges and no background bushes or whatever showing. Your painting should look finished. Take the time to go over it inch by inch to clean up any hastily painted areas that you meant to get back to, but never did. Make sure your painting is framed appropriately and simply, with screw eyes and wire for hanging.

Do not submit copies of another artist's image! That includes photographs, even if you have altered them slightly.

If you are submitting more than one image, make sure they are all the same style—don’t throw in a couple of landscapes and an abstract in the hope that something will appeal; it makes you look like an amateur.

Do not handicap yourself with a trite subject painted in a trite manner (unless you are really good!) If you pick a trite subject, like a vase of flowers, it should look distinctly different from all other vases of flowers. As you can imagine, this is really hard to do!

How and when should I varnish?

Depending on the thickness of your paint, anywhere between three months to a year for very thickly painted works. Remember that oil paint dries from the top down and the surface may appear to be dry while underneath the paint is still wet. Varnishing seals the surface and prevents the paint from drying further, causing cracking. If the painting is not going to be in your possession long enough, a light spraying of retouch varnish will give some protection and shine while still allowing air to get through.

How can I get an even shine on my paintings?*

Many factors affect shine, from the pigments themselves (which have varying degrees of shine), to the thickness of your paint layer. Also affecting the shine is the amount of medium you used; more medium = more shine.

Note: using mediums that contain stand oil creates patches of glassy shine and a slick surface in areas where it is used heavily, and may make the contrast between medium-rich areas and those with no medium even more obvious.

It helps to “oil out” your paintings after they are dry by applying a thin coat of medium over the entire painting. (Be sure to do this with the painting lying flat and in a spot where you can clearly see light on the surface showing you where you have shine and where you don’t.) Sometimes this is all you need to create a more even shine, but frequently the medium beads up or rolls away from patches of the painted surface and will not adhere.

If this happens, blot up the medium in the affected areas and then lightly dab on some mineral spirits or standard Turpenoid to dissolve whatever is causing the resist. After applying the paint thinner, take a clean paper towel and sweep over the entire surface very gently to blend the areas of thinner and medium together and to remove excess liquid. After a couple of hours, reapply the medium in the areas that still look dull. (Sometimes when you sweep it all together the shine evens out by itself). Blend the new application gently into the old. Be prepared to let the medium dry as much as ten days.

Note: Oiling out does not take the place of a final varnish coat.

*I have been using a new method that makes the whole shine control much easier!  I add a small amount of Res-n-Gel (Weber) to each color on my palette, mixing it in thoroughly.  When I need to thin the paint, I use Liquin.  Because the Liquin is used only with paint that is already has a drier added to it, there is no danger of mixing fast and slow drying paint incorrectly, AND it evens the gloss in the paint!  (And the paint will be dry the next day!)


When you are glazing or oiling out, be sure to frequently check the glaze under a raking (from the side) light to catch sags and drips in the glaze. Once these are set they are difficult or impossibly to remove.