Project Description
Encaustic adhesion: classic pitfalls & tips
Encaustic adhesion to the substrates (or the lack of it) is a mayor issue in the encaustic practice. On the one hand the encaustic practice is very new. On the other hand mix-media and new materials are very tempting to artists always looking for new challenges. On top of it there is practically no information about this issue. If you are one of the pioneer-artists looking for new materials at the bottom of the page you will find an easy encaustic adhesion test (that you will 😍…).
The encaustic medium versatility makes the encaustic technique very tricky if you don’t know what all this “encaustic adhesion” is about.
Índice / Contents
Encaustic durability: What you need to know
Encaustic durability is directly related to:
- Lack of adhesion to the substrate (delamination)
- Lack of cohesion (lack of adhesion between wax layers)
- Stresses as consequence of extreme temperatures during transport
- encaustic adhesion principle
- encaustic cohesion
We will review three mechanisms that have great impact in the material failure
Adsorption – wetting or sizing
The adhesion results from the molecular contact between two materials that make intimate (molecular) contact with the substrate.
The process of establishing continuous contact between a liquid element (wax in our case) and the substrate surface is known as “wetting.” The figure below illustrates good and poor wetting. Good wetting results when the wax flows into the valleys and crevices; filling pores, holes, crevices and micro-voids on the substrate; poor wetting results when the wax bridges over the surface irregularities.
Chemical Bonding
Certain binders (like casein or hide glue) have a functional group that can chemically bond wax molecules more tenaciously. These strong and durable bonds require close contact (or adsorption) of the wax on the surface followed by a chemical reaction.
Mechanical Interlocking
This adhesion results from forces developed by the wax penetrating the irregularities on the surface, displacing the trapped air at the interface, and lock-on mechanically to the substrate.
Mechanical adhesion develops in two ways: First, the irregularities increase the total contact area between between the wax and the substrate over which chemical bonding can develop. Second, The irregularities give “tooth” to the substrate. See image below.
Another benefit of mechanical interlocking is that a rough joint will provide a thermal stress (due to extreme temperatures) propagation barrier preventing an accidental fractures and spliting during extreme weather conditions and thus increasing encaustic durability.
Tips to improve encaustic adhesion = encaustic durability
Good encaustic adhesion results when the following occurs:
When the wax flows freely over the substrate and make intimate contact with the substrate.
- By cold weather always warm the panel with the heatgun or over the heated palette (to body temperature) before sizing
- Let the brush stand 3-5 seconds in the encaustic medium between strokes
- Fuse thoroughly with the second layer, give special attention to the sides.
- By cold weather before applying new wax to an already sized panel, wipe the wax surface with a clean paper towel and warm the existing wax layer to body temperature before applying a new layer on top,
- Do not forget to fuse all layers.
When chemical bonds are formed at the interface between the wax and the substrate
- If you use gesso you can use casein or hide glue gessoes, since they build chemical bonds with the wax.
When the wax penetrates the roughness on the substrate surface, resulting in mechanical interlocking once the wax cools
- If you make your own gesso you can use crushed fillers, instead of chemically precipitated ones, to increase the interlocking effect.
- If you paint directly on the wood, you can crosshatch with a cutter the surface
Acrylic gesso for encaustic
The total adhesion between materials is the sum of all three forces, you may use acrylic gesso for instance (does not bond chemically) provided you increase the adsorption or the interlocking effect.
You can find how to modify an standard acrylic gesso to make it suitable for encaustic in one of our recipes. Below you can register to access the downloadable files.
Encaustic adhesion test made easy
If you want to know if an specific material is adequate for encaustic you can try the following:
- Make a small sample of the new substrate you want to test
- Apply the 2-3 wax layers as you would do normally, wait 3-4 days (better if cold)
- Cross-hatch the surface every centimetre with a cutter
- Apply wide cello tape assuring perfect contact to the wax
- Peel vertically in one only movement
Analyse the results
- No peeling or trace peeling – excellent
- Removal only along incisions – acceptable
- Removal from most area – unacceptable
If you want to download the Porous acrylic gesso recipe please sign up for the Modernist Encaustic Club
This post is also available in: Spanish
excellent information , as always ! Thank you Mathilde
Thank you for being such an incredible artist!
Gosh, in this day and age, science and rationality are very much appreciated. Excellent article and hello from Canada Mathilde!
Thank you Linda! 🙂 New ideas to write about are always welcome!
Thank you for the article. I have a question please. My student purchased refined beeswax from Amazon. The wax will not cover properly, seems rubbery somehow., I cant remember now but it may have been triple filtered. Can you hazard a guess as to what the problem is?
Hi Sharon, most probably the beeswax they bought was adulterated. Please send a photo of the label an any other written information, to see what is in it.
Hi,
I’ve been experimenting with applying encaustic tecniques to carved and modelled wood sculpture (fish). I’m not entirely satisfied with the results. I expected issues with compound shapes and there is some chipping and flaking in areas where there isn’t much surface area. Controlling the heat and application to the compound curves and shapes is the real problem – getting consistent layering/fusing and colour modulation.
Can you recommend a particular method for applying encaustic to three dimensional surfaces that might provide more consistent results and less waste? (A porous binding agent on the substrate? More or less damar? Lower/higher heat control? Hotter or cooler temperatures for wax?)
Models have been carved in hardwood. I’ve been using yellow unrefined beeswax/damar in different proportions directly onto the wood for better adhesion.
Awesome encaustic site – thanks!
Chris
http://www.Stonestudio.ca
Hi Chris, can you send me some photos of your 3D work? We will think about something together
Hi Meg,
How and where do I copy and send images?
I’m not able to copy/paste, drag or send mages within this text box. I don’t see an attachment tab.
Can you advise – I’m using an IMac.
thanks,
Chris
You can send me the images /comments by email askpuffin@modernistencaustic.com
Hi there, I have a question, as I have created something of my own….
My product is made of wax, a combination of beeswax and paraffin.
I have been designing my product with encaustic mediums and alcohol inks…
I wipe my wax shell down first with alcohol rubbing solution, then warm the surface that I want the encaustic to adhere to, and start with just two coats of encaustic medium….fusing in between.
But I have noticed now that there are air bubbles forming in between the shell (product) and the encaustic medium.
to the point where it can almost peel away. I understand that the surface is probably not compatible with encaustic, but was wondering if you knew at all if there was a primer or product that I could use on the shell of my wax surface prior to brushing on encaustic to help adhesion? Desperate for your help, I live on an island out in the middle of the pacific ocean and currently visiting Australia, if I could get what I need while I am here this would be so much easier than trying to get shipped to the island. Thank you in advance
Hi Justine, I am sorry for the delay. I do not know any primer that could help you solving the adhesion problem you mention. 🙁
I have recently started playing with encaustic monotypes on japanese paper. The paper is absorbent and is completely saturated. I want to mount on panel for framing. So the advice is if the paper is saturated, you bond the paper to the panel using a layer of wax.. I tried it and if I just place the paper on the wax there are air bubbles. To remove the air bubbles, you need to apply pressure from the center outward. But when you do that you smear the monotype. If you put a newprint on to before applying pressure, then a good part of your monotype is lost to the newsprint.
So I would like to do a cold method such as a glue. I see you are suggesting casein or hide glue. Is that archival with paper? Is it strong enough to hold the saturated paper over time? Any suggestion would be appreciated.
Thank you Marie, It is complicated to mount an already saturated paper on a panel, I suggest that you find a different option for mounting it that does not require the wax to adhere to any other material.
There is some minor drywalling taking place near my studio. There is a very small bit of dust that has gotten into my studio and on my new pieces. And I do mean very minor amount …will this affect any of my liquid wax or my pieces which are setting up? Will it affect layers adhering to each other?
Thank You Pamela, this dust you mention will most probably stick to any wax surface. Unless is massive amount I do not think this will affect the adhesion between layers.