Acrylic Gesso (Acrylic Dispersion Primer) can form cracks in its surface after application due to several factors related to its application, drying conditions, or the surface it is applied to.
First, it should go without saying that I would not recommend that anyone paint on a ground that is displaying any structural issues (like cracking-unless of course, this is intentional.) Second, I would like to share that the ONLY acrylic dispersion primer (acrylic gesso) that I use is Liquitex Professional Gesso. There are far too many problems with cheaper primers and ultimately it just isn’t worth it. If you would like to see how I prime my panels, please read:
Here are some of the most common causes, along with several tips to avoid a cracking issue:
1. Too Thick an Application
Applying gesso in overly thick layers can cause it to dry unevenly, leading to cracking. Gesso shrinks as it dries, and if the outer layer dries faster than the inner layers–the resulting stress can cause structural issues like cracks.
2. Improper Surface Preparation
If the surface (substrate) is contaminated (too smooth, dusty, or greasy) the gesso may not adhere properly, leading to issues like cracking.
3. Flexibility of the Substrate
Gesso is somewhat rigid when it dries. If applied to a flexible surface (like unstretched canvas), movement or bending can lead to cracking.
4. Environmental Factors
Rapid changes in temperature or humidity can cause cracking. For instance:
Drying too quickly in a hot or windy environment may create surface tension that results in cracking.
Extreme cold can make gesso brittle and prone to cracking.
5. Incompatible Layers
If multiple coats are applied without allowing each layer to fully dry, or if there’s a significant mismatch in the flexibility of layers (e.g., acrylic gesso over an oil-based layer), cracking can occur. (please look to our common schedule for acrylic gesso application, which recommends 24 hours for the first layer and 12 for each subsequent.)
6. Old or Poor-Quality Gesso
If the gesso is of poor quality (cheap), old, or improperly stored, its composition may degrade, leading to cracking when applied to a substrate. Cheap or poorly formulated gesso can also lack the flexibility and adhesion necessary to prevent cracking.
7. Incorrect Dilution
Diluting gesso with water can significantly weaken its binding properties, making it prone to cracking when it dries. Please follow the manufacturer’s recommendations on dilution if you choose to dilute.
How to Reduce any Chances of Cracking:
Apply moderate, even coats of gesso, allowing each layer to dry thoroughly before adding the next. (again, see our recommended wait times above to follow our method of acrylic gesso application.)
Ensure the surface is VERY clean, slightly textured (to increase surface area), and suitable for gesso application.
Use high-quality acrylic gesso and avoid dilution altogether if possible.
Maintain a stable drying environment with moderate temperature and humidity.
If using a flexible substrate, consider using a flexible primer.
By addressing these factors, you can reduce the likelihood of cracks forming in your acrylic gesso.
As always, research your materials prior to use!
Happy Painting!