Saturday, January 2, 2010

A masking fluid tutorial...

Yesterday's post on watercolor masking fluid generated a lot of interest and feedback. Lots of strong feelings out there on the subject -- particularly when it comes to the brand!! I decided this topic deserved a little more airtime.

I've been using masking fluid since I returned to watercolor 15 years ago -- starting with very experimental spattering techniques and eventually moving to controlled use to preserve whites or to allow me to create background washes around complicated shapes. Although some artists use frisket film in combination with the fluid, I have always coated all masked areas with fluid to make sure all surfaces behave the same after I remove the masking and start adding paint. I use a variety of masking fluids and tools to accomplish my goals, as you can see in the photo above.

You can see the various masking fluids I use, brushes (a size 2 and size 6 are all I need), my bucket of soapy water and the little container of liquid dish soap, the sharpened wooden handle of an old cheap brush, a toothbrush for spattering, a ruling pen, and a couple of different nibs.

Inexpensive white synthetic brushes seem to work best with masking fluid. (Whatever you do, do not use a fine watercolor brush to apply it.) Yesterday's post includes information on how I keep the brushes in good condition. Although I've never tried it, some people use Goo Gone or other solvents to rescue clogged brushes.

The supernib plus from Masquepen is in the upper left of this closeup photo, along with the fine pin they include to help clean it. At middle right is a bottle marketed by Jacquard for silk painting -- three different nibs are available and what is shown is the mid-size one. The metal nib screws onto the little plastic spout which pops into the bottle top. When I'm using this, I put the straight pin into the nib to keep it open when I take a break. These nibs seem to work best with slightly thicker-bodied fluids -- Pebeo and Incredible White Mask -- and are fairly easy to clean because of the short tip.

The ruling pen, shown at the bottom of the photo, can be adjusted to give lines of varying widths. I find the Winsor Newton fluid works best because it flows easily. A line width of about 1mm seems to be best for outlining rectilinear shapes. You can also create finer lines for special things like cat whiskers or tiny plant hairs, but it's difficult to make very thick lines because the pen doesn't hold enough fluid to go very far. This tool is very easy to clean by wiping it thoroughly and/or peeling off any dried masking. You can go here, here, or here to find ruling pens.

I got an Incredible Nib with my first purchase of Incredible White Mask, but I've never found it to be useful.

Don't buy large quantities of masking fluid unless you're planning some big projects. Pebeo tends to seize up in the bottle over time and Incredible White Mask can be difficult to remove if it's old when applied, even if you don't leave it on the paper very long. A sign that it's too old is the color -- when fresh it's the color of cream, and it gets very yellowed when old. Although I don't always remember to do this, it's a good idea to date your bottle when you buy it.

Slightly thickened masking fluid can be thinned with a very small amount of plain ammonia. I always stir the fluid rather than shaking it, after reading some years ago that shaking caused the latex particles to clump and separate out of solution, making the stuff useless. Yet several manufacturers instruct you to shake the masking fluid before using. Although I often save technical information, I can't find the article I read. If anyone has more information on this matter, please leave a comment.

Masking fluid must be applied to perfectly dry paper and your painting must also be perfectly dry before you remove the masking. You can remove it with your fingers or with a rubber cement pickup (a small square that looks like a piece of a crepe sole) if there's a large amount to remove.

After removing the mask, you'll have bright white shapes with hard edges. It's this characteristic that leads many watercolorists to reject the use of masking fluid. However, by softening the edges and/or painting in the shapes, you can integrate them and create an esthetically pleasing painting. But that's a topic for another day!!


  1. What a GREAT tutorial on masking fluid. There were several things in it that I did not know! (Adding ammonia for instance...although keeping ammonia around wouldn't be my first choice.) I have added a touch of water to Pebeo (in a small container and it seems to work. I store my masking fluid upside down. This seems to help AND some people keep theirs upside down IN THE REFRIGERATOR and claim this adds to it's life! I buy it small and then I pour it into a little film canister with snap lids while using it. (yes you can still find those...ask at Walgreens photo department or photo development stores...they will give you a bag of them free!). Thanks so much for info on ruling pen which I have never HEARD of!

  2. Fantastic tutorial! Thanks so much. I didn't know about the ammonia.

  3. Good info - thanks for that, Chris :) I put a marble in my bottle of Pebeo to keep it from gumming up but it does gum when it's older and you're getting down to the bottom 1/8. I like the ruling pen idea.

  4. Thanks for the comprehensive look at masking fluids and methods of application.

    I have only used Winsor and Newton liquid applied with an old brush and sometimes the end of a brush. I often prefer to just work around the shapes I want to preserve, but I know that's not always possible.

    I shall have to investigate the wider options for this tool.

  5. Thank you! Very thorough information on masking.

  6. Thanks for the tutorial, Chris. It's great for beginning artists, and a good refresher for those who have painted for a while. And also thank you for your belated thank you(s)! Glad you enjoyed the cards.

  7. Well, I see that I could extend this tutorial to cover even more ground!! Thanks for all the feedback and suggestions.

    Because the liquid in masking fluid is ammonia, it's a logical choice for thinning the stuff. But caution is needed - add only a drop or two, stir and evaluate. If you get it too thin, it won't work properly.

    I have tried storing the bottle upside down, but didn't notice that it improved the shelf life. Perhaps I had an old bottle to start with. It's certainly wise to check the bottle before purchasing it if you buy at a local art supply store. I've seen entire shelves of masking fluid that were so far past their useful condition that it would have been a waste of money to purchase a bottle.

  8. Elizabeth Kincaid's 2004 book, "Paint Watercolors That Dance with Light" (North Light Books) includes a section on masking that describes masking fluid as suspension of latex in ammonia and that shaking it can "encourage the latex to come out of suspension," eventually leading to the latex clumping and forming a ball..and ruining the bottle of masking fluid. That section in Kincaid's book was the first time I had ever read any definitive dos and don'ts with masking fluid. She also stresses that exposing the bottle to excessive sunlight can damage the suspension, and that the skin that forms on the surface after the liquid is exposed to air should be regularly, and carefully, removed. Perhaps this is the article you remember, Chris?

  9. Thanks for leaving that helpful comment, Kristen!! I only recently bought a copy of Elizabeth's book and hadn't had a chance to look through it. I just reviewed her section on masking fluid, and that information seems familiar -- perhaps she wrote the article that I recall from some years back.

  10. Thanks for the tips, Chris!

    I always have trouble with masking fluid so these tricks will come in handy!!


  11. Thanks, Dean! Glad you found this useful -- it's all a lot more fun when the technical stuff works!!

  12. thanks for the vital informations about the fluid masking. can you suggest any alternate masking matarial because the ary material stores in my city do not have fluid masking. pls help.

  13. Prem, is there any way for you to order through an art supply catalog and have things shipped to you?

    Otherwise -- and I would not normally suggest this -- rubber cement can be used as a masking substance if you have no other choice. I would only leave it on the paper for a short time -- no more than a day or two. Even with that precaution, there is a possibility that the chemicals in the rubber cement might cause slight yellowing of the paper over time. I would only use it for details that I could not paint around easily.

    Be sure to use it in a well-ventilated area, as most brands of rubber cement contain volatile solvents.

  14. Now they twll me not to shake the i remember the shopkeeper insist that i shook the bittke b4 wonder it clump the second time i use it....what a waste as it is very expensive in my area.....and i tried hunting for rubber cement but no success...but usefull tutorial tough

  15. I'm sorry you were given the wrong information by the shopkeeper, Eliza. If you cannot find products you need locally, perhaps Jackson's ( in London would be a possibility. They do ship worldwide I believe, but I don't know how expensive that would be. Glad you found my tutorial useful.

  16. Is there a way to remove or clean the masking fluid out of the container? I have used these little dippy dot containers with each project and would like to clean them rather than throwing them out. Thanks!

    1. Once masking fluid dries, I don't know of any way to remove it other than pulling it away from the surface. Obviously that would be impossible from the inside of a small bottle. Sorry I can't help.


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