Image Transfer with Pyrofoto: Another Cool Way to Put Images on Pottery

There are various processes for transferring images to clay, from photocopy transfers, silkscreening and stencils, to laser transfer decals and commercially made decals. There is also a process that’s designed specifically for working with glaze. Pyrofoto is a product that works with the traditional photography concepts of exposing a surface to light through a negative, then developing, processing, and fixing the image.

Our own Jessica Knapp puts Pyrofoto to the test, and in today’s post, she tells us all about the process and her results. Take it away, Jess! – Jennifer Poellot Harnetty, editor.

 


 

There are various processes for transferring images to clay, from photocopy transfers, silkscreening, and stencils to laser transfer decals and commercially made decals. There is also a process that’s designed specifically for working with glaze. Pyrofoto is a product—made by Rockland Colloid (www.rockaloid.com), the makers of Liquid Light photographic emulsion—for use on glaze-fired pieces. It works with traditional photography concepts of exposing a surface to light through a negative, then developing, processing, and fixing the image. However, unlike traditional photography processes, no expensive equipment, chemicals or darkroom are needed.

How It Works

Pyrofoto is a liquid sensitizer designed to be mixed with glaze and used on a piece that has already been glaze fired. The glaze/sensitizer mix is applied to an already glaze-fired surface, and exposed to direct sunlight, a work lamp, or a high-wattage (250-watt) halogen lamp through a high-contrast transparency image. (Note: Normal household incandescent bulbs will not work as they do not provide the right wavelength.) Where the Pyrofoto mixture is exposed to light (in areas not blocked by the ink on the transparency), it hardens like a resin and becomes fixed to the surface. The pot is then wiped or sponged with cool water to dissolve away unexposed areas, leaving only the glazed image behind. The piece can then be fired again to set the image permanently.

Creating an Image

First, choose your imagery and create a black-and-white transparency using an inkjet or laser printer or copier. High-contrast photographs, illustrations or your own drawings will work best with this process, so avoid images with lots of mid tones, or alter the image using photo editing software to increase the contrast.

Make sure your printer or photocopier is set to “best quality” before printing the transparency. If ordering the transparency at an office supply store, ask for a high quality print. This ensures that the black areas, which resist the light and therefore result in unexposed areas, are saturated and opaque. Remember that the black areas of your image don’t remain once the process is finished. Think of these areas as the negative space. If you want these areas of the image to remain, alter your photo to create an inverse image; make the white areas black, and black areas white.

To create a multiple-color image, you’ll need to do one of three things. Make a separate transparency for each color, just like color separations are needed for screen printing, work with a contrast between the base glaze and your Pyrofoto/glaze mixture, or selectively apply different Pyrofoto/glaze mixtures to the piece based on the colors in your image.

Mixing & Applying Glazes

1. Mix an equal volume of Pyrofoto with a thick glaze, and brush one coat onto the glaze-fired surface. Once it dries, brush on two more coats and allow this to dry.

Once you know the colors you wish to use, mix one part of the Pyrofoto sensitizer with one part of your liquid glaze by volume. If you use powdered glaze, reconstitute it to a thick consistency first (at least as thick as slip for slip trailing). Note: Wear gloves and a respirator while working with Pyrofoto.

Tip: For best results, use a thicker glaze with high colorant concentration. Watery glaze won’t coat well. If the color or pigment isn’t strong enough, the image will be faint.

Clean your already glaze-fired piece by scrubbing with powdered laundry detergent and rinse with hot water, then dry. Prepare test tiles as well to use as exposure test strips.

2. Place a high-contrast transparency over the piece, secure it to the surface and expose for 5–15 minutes.

Apply a thin coat of sensitized glaze by brushing, then allow it to dry (figure 1). Next, apply one or more heavier coats. Dry thoroughly at room temperature. You can use a fan or a hair dryer on the cool setting, or let the pieces air dry over several hours. Note: It is much more challenging to apply Pyrofoto to three-dimensional forms. In addition to the recommended method, I also pre-heated some pieces to 200°F prior to applying the glaze to accelerate drying and avoid drips. Both methods worked, but the recommended method yielded a crisper image. Try both as your results may vary.

Exposing & Developing

Use your test strips to determine your exposure time. It will be between 5–15 minutes. My images required 15 minutes. If the unexposed areas don’t dissolve, the image is overexposed (shorten the exposure time). If all of the glaze washes off during processing, the image is underexposed (increase the exposure time).

Position the transparency onto your piece (figure 2). For flat tiles, the exposure time will be straightforward and based on your test strips. If you’re working on a curved surface, the time may be different if not all areas can be exposed at the same time. Set up multiple light sources, or add the image and expose it in sections.

3. Gently wipe away unexposed areas using a damp sponge. The image will gradually appear.

After exposing the image, develop it by gently sponging or wiping with cool tap water (figure 3). Don’t use a lot of water as this will dissolve the image. I used a damp sponge. The unexposed areas, which look lighter or slightly greenish-yellow in color n comparison with the rest of the glaze, will gradually dissolve. It may take several minutes for the image to appear. Don’t brush or sponge aggressively as this may damage the image. For detailed areas, use a small, cut piece of sponge to remove the unexposed glaze. Note: The unexposed glaze should be collected in a bucket rather than allowed to go down the drain. Like other used glaze materials, it should be disposed of properly or fired in a waste bowl like other glaze scraps to render it inert.

When all of the unexposed areas are removed, blot and dry the image. If you want, you can apply a second color and repeat the process. When the glaze dries, fire the piece to the appropriate temperature.

The cup shown here has a shiny base and a shiny transparent Pyrofoto/glaze. It was fired to cone 4.

Pyrofoto can be purchased directly from the Rockland Colloid website, or by phone at 503-655-4152. Many of the company’s products are also sold through photo supply stores.

 


**First published in 2011
Comments
  • Very interesting. Does anyone know how much the pryofoto costs?

  • Karen M.

    Website has prices…$25 for half pint and $45 for pint. Very interesting process.

  • Jeannelou T.

    If you want to use the piece for food, can you re-glaze it with clear glaze?
    Thanks for the ideas,

  • Jennifer H.

    JeanneLou-

    As long as the glaze you are using is food safe, there is no need to apply clear glaze overtop.

  • TOBY C.

    I Imagine your could use ammonium bichromate and pva glue(Elmers), or gelatin or gum arabic as a substitue for the Pyrofoto….. the ammonium bichromate is highly carcinogenic so use a respirator latex gloves and who would want to even be around the fumes? ive used the above mixture for gum prints, gum oils and to make my own photo emulsion for screen printing.

  • Knapp J.

    JeanneLou, the base glazes I used were food safe, that’s part of the beauty of using this product; it works with whatever glaze that you want to use. The clear glaze was applied, then fired to temperature. The blue glaze, which was the same base as the clear but with a blue mason stain added, was mixed with Pyrofoto, exposed through the transparency, scrubbed away in unexposed areas, then refired to the same cone as before (cone 6). So, the glazes you mix with the Pyrofoto and the firing temperature you take the glazes to will determine whether the piece is food safe or not. The binders and other organic materials in the Pyrofoto burn out during the firing, leaving behind only your glaze. If you already have food-safe clear and colored glazes that you like working with, you should not have any problems. When in doubt, I recommend having the durability of your glazed ware professionally tested for you.
    Here are a couple of resources that can help you get started:
    1. Brandywine Science Center, Inc.
    204 Line Road
    Kennett Square, PA 19348
    Phone: 610-444-9850
    Fax: 610-444-4080
    Web site: http://www.bsclab.com/

    2. CERAM RESEARCH http://www.ceram.com/testing
    Location: Stoke-on-Trent, UK

    Additional resources can be found on Labs page on the Digital Fire website:
    http://digitalfire.com/services/database.php?list=labs
    Good luck!

  • Sorry, I just found the answer to my question. Thanks for an interesting technique.

  • this seems dangerous, either in the use, the firing or after,,, this is the chemical that made Erin Brockovich famous
    Per the MSds sheet s on the site this is Ammonium Hydroxide and Ammonium Dichromate

    From the product supplier site
    Health Hazard Data
    ==========================================================================
    AMMONIUM HYDROXIDE: Potential skin irritant causing gray splotches, burning
    of throat, coughing, difficulty breathing, pulmonary congestion.
    AMMONIUM BICHROMATE: Corrosive; potential sensitizer (skin); human carcinogen
    (IARC=1; NTP=known); potential liver and kidney toxin.

  • So very cool. This subject has intrigued me for years. I was taking a digital printing class and had Easy Decals make a photo decal for me, very reasonably, and I fired it on a hand built platter, but now they are out of business. I still dream of working with this process. Had the recent good fortune of seeing Jason Bige Burnett demo some of these processes while I was at Penland. I have Kevin Petrie’s book on Ceramic Transfer Printing. Thanks so much for sharing.

  • Genevieve N.

    Since this product is costly and dangerous for people and the environment, and the process also wasteful, I hope people don’t throw the wiped off glaze down the drain!
    Which brings the question: is it possible to re-use the wiped off glaze since it was not hardened by light ? That would be useful and more environmentally friendly.
    Also, why does it have to be applied to an already fired pot ? Can’t it be done like raw glazing or on a bisqued pot ? Obviously, when you apply a glaze to an already fired pot, the amount of glaze will be minimal. It’s hard do reglaze an already fired pot. The second layer of glaze always runs off a lot. Which can bring beautiful results, I know.

  • Genevieve N.

    I forgot to add: the fact that the transparency can be re-used over and over again, I suppose, is a bonus, though!

  • Darryl W.

    Sheet film limits application to singly curved surfaces.

  • Knapp J.

    Genevieve, Thanks for your comment. I have included information on proper disposal in the post to clarify that. I wore gloves throughout the process, as well as a respirator that is rated for fumes as well as particulates.
    The layer of glaze applied was thin, and the amount of glaze mixed with the Pyrofoto was minimal, so there was not a lot of waste with this process. Addressing the cost and waste issue, I think that if you’re interested in this process, the smaller bottle of Pyrofoto would last a while. When applying it, I mixed 30 grams or less of glaze with the equal amount of Pyrofoto to be sure that I was not wasting either. I mixed more only as needed. I suppose the amount of glaze you wipe off will depend on the complexity of your pattern or image. I did not try to reuse the glaze that was wiped off. The waste glaze can be collected with your other glaze scrap and can be fired in a bisque mold to the maturing temperature of your glaze to render it inert before disposal. Firing either of finished works or of glaze scrap should always be done in a well-ventilated area, and the kiln itself should be ventilated.
    As to applying a Pyrofoto/glaze mixture to bisque or green glazing using this, I did not try those techniques but I have doubts about the success of doing either for the following reason. As glaze absorbs into both bisque and greenware, despite the fact that the unexposed areas would not be hardened, these areas would be very difficult to clean off completely. While working to wipe the glaze away from these areas, I think it would be likely that some of your image would also be eroded away, as a delicate touch was needed to preserve the image even over a glazed surface. All of that said, if anyone experiments with this product on either bisque or greenware and has success, please post your results!
    Applying the glaze/Pyrofoto mix to glazed ware can be aided by preheating the piece to 200 degrees F before application.
    I hope this helps!

  • Rebecca C.

    Would love to see a video of this – hint hint.

  • I suppose this is an interesting enough technique, however I can’t understand why anyone would want to have to buy specialized equipment and risky chemicals requiring special handling when one can achieve very similar if not exactly the same effects with much simpler, well known techniques. Why is it that nine times out of ten we don’t get to see the finished product??

  • Leanne F.

    Is there potassium dichromate in the Pyrofoto mix? Interesting technique. I have tried similar photo transfer method with potassium dichromate mixed with gum arabic and honey to produced very similar results. However, I was never able to fully stabilize the image when washing off excess dichromate.

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