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Painted girl Jo Sonja Crackle Medium

There are two mediums for crackle effects in the Jo Sonja range: Crackle Medium and Décor Crackle Medium. It is important to know the differences so you can achieve the effects you want.  Test these techniques to see what you like best!

Jo Sonja Crackle Medium is what cracks, and it may also crack the paint, depending on how long that paint was dried.  Many times, with Crackle Medium, applying a glaze enhances the crackle pattern.

Jo Sonja Décor Crackle is a sandwich crackle and will crack a top layer of paint when applied.

Crackle Medium

Jo Sonja Crackle Medium is a transparent medium, which causes Jo Sonja Matte Flow Acrylic and Background Colours to separate into fine crazed or crackled patterns in a one-step process. Use to simulate the effects of aging. Recommended for use with Jo Sonja Matte Flow Acrylic and Background Colours only. We suggest you test your technique before committing to a project.


  • Apply a thin coat of medium for fine cracks, moderate coat of medium for medium cracks, thick coat of medium for large cracks.

Background Crackle:

  • Prepare surface by sealing and applying basecoat. For one-step preparation, mix All Purpose Sealer and the basecoat color beginning with a ratio of up to 1:1 for the first coat only. Allow to air dry and lightly sand. Apply additional coats without the addition of All Purpose Sealer.
  • When final basecoat is dried to touch, apply Crackle Medium working a small area at a time with brush suitable to surface size. Work quickly using a criss-cross motion to apply Crackle Medium. Slightly blend out the brushstrokes as you apply the medium. The crackle pattern will follow the direction of the brushstrokes. Do not brush back over previously applied medium that has started to dry as doing so may cause the Crackle Medium to lift. Crackle Medium will level out slightly as it dries and will dry clear.
  • Allow to air dry undisturbed.
  • Crackle Medium is formulated to separate into a crazed or crackle pattern as it dries. Paint layers that have dried but not cured may also separate. The thicker and fresher the paint, the deeper and cleaner the crackle pattern will be. DO NOT USE A HAIR DRYER between coats of base color. Warm air will cure the paint and prevent the crackle from working properly. The base color will show through the crackle pattern if an uncured contrasting color is applied before the application of the Crackle Medium.
  • After crackled surface is completely dry, gently sand surface using #400 to #600 grit sandpaper until desired smoothness is attained. Wipe to remove dust. Any that remains in the crackle pattern will disappear with antiquing or glazing.
  • Crackle Medium will leave surface slick. Pattern application may need to be modified. Light sanding should decrease “slickness” of the surface.
  • Antiquing may be applied to the surface to accentuate the crackle pattern. If painting is applied over the crackled background, 1-2 coats of Clear Glaze Medium may be applied as a barrier coat. Thin contrasting color with Retarder Medium and brush into cracks. Remove the excess with a soft cloth moistened with Retarder.
  • Allow to dry completely before varnishing. A coat of Clear Glaze Medium is recommended prior to varnish application.
Crackle Medium example (detail)


  • Crackle Medium can also be applied after painting the design or over photocopies or prints, which will produce fine crazing for an aged effect. A coat of Clear Glaze Medium is recommended prior to crackle application. You may choose to antique the surface to accentuate the crackle pattern. A light sanding before antiquing is recommended.
Laser print with Clear Glaze and Crackle Medium, after antiquing

Décor Crackle

Jo Sonja Décor Crackle is a sandwich crackle medium for application between layers of paint. The top color separates to reveal base color giving the appearance of aged paint. Décor Crackle is available in the Crackle Pack set..


  • Seal and basecoat surface with color desired to show through the crackle pattern. Surface must be sealed to allow Décor Crackle to work properly.
  • For best results, one-step preparation is recommended.
  • Apply basecoat color mixed with All Purpose Sealer 1:1 to the surface. Allow to dry and lightly sand.
  • Brush on an even, generous coat of Décor Crackle. Allow to air dry to touch.
  • Using a brush suitable to surface size, apply a contrasting layer of Chroma’s Jo Sonja Matte Flow Acrylic when Décor Crackle is dry to the touch or within a maximum of 6 hours. As topcoat dries, it separates to create the crackle pattern. The thicker the top layer of paint, the bolder the effect. Crackle pattern will follow the direction of brushstrokes in topcoat application. Use a slip slap motion and smooth as much as possible. Do not over brush or lifting may occur.
  • Topcoat may be applied using a variety of tools for varied effects such as a sponge, cloth, etc.
  • Allow to air dry. DO NOT USE A HAIR DRYER TO PROMOTE DRYING. After drying, sand using fine sandpaper if desired.
  • A coat of Clear Glaze Medium applied before varnishing will help to avoid further crackling.
  • Note: Chroma’s Jo Sonja Metallic, Iridescent and Background Colours are not recommended as a topcoat unless the Combination Crackle technique is used
Decor Crackle example (detail)

Combination Crackle Technique

Combination Crackle uses both Jo Sonja Crackle Medium and Décor Crackle for a “no fail” crackle technique to achieve a time-worn and aged effect.


  • The surface must be sealed to ensure Décor Crackle will work properly. Over a porous surface, mix All Purpose Sealer to the basecoat color 1:1. Prepare the surface using a coat of color or stain and allow to dry. Sand if needed.
  • Apply a coat of Décor Crackle. Dry to touch. Surface should have an even, shiny layer of Décor Crackle. The quicker and heavier the topcoat is applied to the surface, the larger the crackle pattern will be. Apply topcoat within 6 hours of application of the Décor Crackle.
  • For topcoat, mix Crackle Medium with color up to 1:1 and apply following directions for Crackle Medium.
  • For a weathered wood effect, apply basecoat color or Wood Stain Gel and allow to dry. Apply a coat of Décor Crackle to the surface randomly using a toothbrush or a stiff bristle brush. Avoid creating a pattern. Allow to dry. Apply topcoat of color and Crackle Medium following directions for Combination Crackle.
  • As the crackle process begins, a palette knife may be used to slide or remove some of the topcoat to achieve a weathered finish that looks as though the paint has begun to lift and crawl. Allow to dry. A coat of Clear Glaze Medium is recommended prior to varnishing.
  • For best results, store in a cool, dry place out of direct sunlight.

Jo Sonja Matte Flow Acrylics & Mediums Tutorials

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