So, I’ve been curious about using a gesso layer under paint to aid in creating a smooth finish without cracks. I decided to try it out on a horse that I am repairing. The original finish had many cracks, and the joints of the wood had opened up. There were many defects in the wood surface that I hoped to fix. My hope was that  the gesso would help seal everything and prevent more cracking. The end result? I don’t think it helped much, at least not enough to do it again. I used an acrylic gesso, so maybe a natural old-fasioned gesso would be more effective. The traditional kind has plaster of paris in it, I think. It seems gesso does create a super smooth finish, if you don’t have cracks in the wood. In that way it would work really well for what most people seem to use it for- as a smoothing layer on painting canvas. But for wood, it just didn’t help me.

Here’s what I started with

I started with reclaimed lumber that had many flaws. Here are just some of the issues I hoped to overcome: Open joints, poor wood structure, bee holes that I tried to fill with wood dowels and glue…

I used Liquitex Basics Acrylic Gesso. It has the consistency of maybe yogurt? Pretty thick. I had high hopes that it would provide a good thick layer. It goes on fairly easily. I ended up with a thick coat with a lot of brush texture left in it. I planned to sand this out later, hoping a thicker layer would provide more filling of the cracks. You can see it does appear to fill in many of the defects with the first coat before sanding.

After allowing the gesso to dry 24 hrs, I sanded it by hand. This was kind of dusty and I wore a mask. After sanding, I was disappointed to see that many of the defects had already opened back up again. The gesso didn’t work as an effective filler the way I had imagined. Here’s some sanded images…If you can see, some very small seams were filled, but the large defects still stand out.

After this, maybe another couple layers of gesso would help? But I didn’t think it would, it doesn’t seem to act as a filler for cracks over 1 mm deep. I decided to use a wood putty that often works well for me, Durham Plumber’s Putty. It is a powder that you mix with water to create a paste. I applied this to the wood over the gesso. The result was that the putty didn’t adhere correctly. I think the gesso had a negative effect on it. In the future, I think it would be better to apply wood putty first to any major defects. Then maybe a gesso layer would aid in smoothing out the final surface before paint. Here’s my wood putty layer with another layer of gesso on top of that. Defects appear to go away, but after painting, it was another story…

After a final sanding, this did provide a pretty good surface. But again, I think the better process would be to use wood putty first, then sand, then gesso, then sand again. After I applied paint, many of the puttied areas flaked off. I didn’t get any photos of this, sorry. But I think the putty didn’t adhere well to the gesso, creating the problems after painting.

I continued filling cracks with putty and sanding to get a final surface that did hold paint. In the end, I still have open seams and some crackling areas of paint. I sealed everything with shellac to aid in keeping it all together. The result works, and kind of looks like an antique finish. It is stable and does not flake at all. But its not what I set out for. The area around the eye worked out well, but other areas still show the flaws:

Conclusion

What I may try in the future is to apply wood putty to areas that need it. Sand that smooth. Then possibly apply gesso, or I may skip gesso in the future. I don’t notice any benefits that a regular primer coat of my normal milk paint doesn’t already create. I think I will just stick with milk paint in the future.

Maybe I didn’t use the gesso correctly, or didn’t use the right kind, or shouldn’t use it with Durham Putty, or it doesn’t work well with milk paint. I called the milk paint company and they said it usually works great with gesso, so I don’t think that’s the issue. But for now, I just don’t see the benefit of using it. Let me know if you have had other success with gesso!