The thermosetting resins versus paraffin-coated substrates interaction is an interesting diversion of my otherwise sticker-paper research, but the physics of it is strikingly similar. To provide the answer to the burning question: no, there is no permanent, structural way, in which epoxy sticks to wax paper. The manner in which the resin beads up on the waxy surface is very impressive to me. It is a conventional struggle of superficial energy: the wax is a natural though a bit of a messy releasing agent. Since wax is hydrophobic and possesses low surface energy, cross-linking molecules of the epoxy do not have anything to cling to. It helps when you are guarding a work bench, but is a nightmare when you are wishing you were bonding.
What material does epoxy resin not stick to?
The process of working with adhesives can be a sloppy affair, and more so when you have to deal with something as recalcitrant as epoxy resin. Plastics and stickers I have a love-hate affair with these materials after analyzing the molecular interactions between them and polymers over the years. It is a very interesting and a little irritating experience on how materials do not bond. Epoxy depends on a mechanical or chemical bond, and hence it detests low-surfaces-energy plastics. The real fugitives are polyethylene and polypropylene, their surface tension is so weak that the resin just beads like water on the newly-waxed hood. It is almost ridiculous to see a high-grade resin not selling on a plain sandwich bag or plastic storage container. The industrial world uses these polyolefins as the equivalent of the non-sticky pans and therefore they are frequently used in mixing containers or in mold liners.
Next there are the silicones that are in a whole different league. And when I am trying an adhesive to apply to a sticker line, silicone will always be the benchmark of release liners since nothing, and I mean nothing, prefers being stuck on it. It is almost greasy to touch. The cause of that slickness is siloxane bond that forms a surface so slick that it causes ice to appear like sandpaper. When you pour epoxy into a silicone mold, it will pop out with an excellent thwack when it has cured. It is a weirdly touching triumph when a clean release occurs and there is no coerced way. In addition, leave out Teflon (PTFE). It is the monarch of non-reaction. These materials can be found in case you are in a jam and require a work surface that would not destroy your project. Even wax paper, which is frequently misconceived, offers a reasonable temporary seal since the paraffin wax is a sacrificial layer which the epoxy can actually not penetrate. It is all about that toothlessness in the resin to hold on to.
Can you epoxy over sticker paper?
The extreme experience of diving into the world of decals covered with resin is like a lottery where you betting your hard work. The answer to this is yes, but the technical side of it can leave an experienced researcher with a headache. I have spent many hours in examining the conduct of the various topcoats with several adhesives, and the porosity of the paper is your worst enemy. In case you have traditional matte sticker paper the thirsty fiber will absorb the resin so there will be a wet appearance which destroys the color of your design. It is sad to see a clean graphic spoil and become messy and transparent due to the epoxy draining down into the pulp. The only way to counter this is by sealing the surface to begin with. I tend to use an acrylic spray that is clear or some layer of water-based sealant to form a barrier. This will stop the infiltration of the epoxy in the fibers and maintain intactness of the ink.
Vinyl stickers are another thing altogether. They are stronger due to their artificial composition although you must be concerned about the edges peeling up in the process in case the resin produces excessive amounts of heat during the exothermic reaction. In other situations, the sticker paper may have a glossy surface, which makes the epoxy unable to get a hold, and may peel off at the edges as the epoxy material cures. That is the reason why I can always suggest light scuffing, or making the sticker as smooth as possible by having no air bubbles under it, since even the smallest amount of air will be amplified by the resin heat, leaving behind a foul mark. When the resin flattens into a glass-like finish, it is so satisfying, but that cannot be done without careful preparation and thorough knowledge of surface tension. This also requires caution on ink compatibility, there are solvent ink types that can bleed when the resin chemistry is too aggressive.
What paper doesn’t stick to epoxy resin?
It is an obsession of mine to figure out which substrates of cellulose will repel a thermosetting polymer in fact. Most papers are tragically absorbent; however some specialty liners are so designed that they are what we in the lab refer to as an anti-adhesive in a reverential way. The apparent winner is silicone-coated release paper, the material of the backs of expensive high-end stickers. To give this paper its astonishingly low surface energy, it is filled with a layer of silicone so the molecules of the resin lack a place to hold on. It is even nicer to have an epoxy puddle that is cured release itself off a liner and not leave a fiber trail behind. Glassine paper is another competitor that is slightly more temperamental. Since glassine is air-permeable and water-hydra-resistant with a supercalendering process, it does not allow penetration, but is not as dependable as a real silicone barrier.
The wax paper is something everybody wants to know about and it is a fair household solution, but it is very primitive and primitive when compared to the industrial release liners. The paraffin coating acts as a physical barrier however when the epoxy produces high heat as it does anytime such an intense exothermic reaction occurs, it can fuse the wax. As the wax melts, it mixes with the resin forming a cloudy, messy interface which to me is utterly repugnant in terms of quality-control. Other alternatives include parchment paper which is impregnated with sulfuric acid to make it resistant to heat and adhesion. It turns out to be a greasy ally which is sturdier than the waxy counterpart. But, when you want something that is fool-proof, use heavy-duty polyethylene-coated papers. They provide a hard and shiny surface that demolding becomes more of a magic than a task. It is all a matter of the relationship there exists between the viscosity of the liquid and the porosity of the substrate.
How to seal paper before epoxy?
The process of ensuring that there is a clear seal over your sensitive fibers of your sticker and a stream of harsh resin get me so much adrenaline. A failure to seal the epoxy completely will result in the epoxy vaporizing into the paper giving you a messy, clear, and greasy nightmare. My basic rule is to push an acrylic spray sealant, of high quality, at all times–in lots of thin smears, not in a single drippy coat. In this technique, it is then possible to retain the toothed paper and fix the molecules of ink so that they do not drift away during the curing process. One must always allow one layer to dry before adding another; and one should be patient enough to know it when he is doing it on the lab. Another firm path is the use of a water-based decoupage medium such as Mod Podge, although, again, brush strokes should be considered. The resin is able to magnify tiny ridges forming an optical nightmare.
The other method I consider very ingenious is the application of a clear laminate or even a plain sheet of transparent packing tape to do smaller decals. This offers a physical plastic barrier onto which the epoxy can never penetrate effectively armoring your sticker in the process. And, with complicated figures, still the spray is your friend. Close the edges and the back, in particular, when the sticker is not already put on a surface. In case the resin slips behind the paper, it will give an uneven and mottled appearance which is not so nice to look at. Its chemistry is really rather fancy–you are really designing on a microscopic scale a kind of shield to keep your art out of the path of an attacker, a fierce chemical attacker. It was a fine balancing act between the solvent contained in the sealer and the glue in the sticker paper.
When should you not use epoxy?
Using the wrong environment to apply a resin is a disaster waiting to happen, and it is so bitter to imagine a good sticker project being spoiled due to the misuse of time. Epoxy should in no way be used in situations where the humidity is so high; it is more than sixty percent. Humidity in the atmosphere combines with the hardener of amines to produce a blush, a oily, foggy coating to the surface. It causes the end product to look amateur and sticky to touch, which is not very luxurious as we want. Whether it is a frozen tundra that you are in, put the bottles aside. Epoxy is a high fussy creature, which must have a moderate climate to start cross-linking. When it is excessively cold the mixture will remain syrupy days or worse still, it will cure with a brittle fragile framework that breaks at the least provocation.
I also become anxious when individuals attempt to use epoxy on wet or un-cured surfaces. When your sticker ink or sealant has not outgassed completely, you are essentially putting volatile organic compounds in a plastic dome. That causes small bubbles which appear as a case of the bending of your art. Besides, never even consider applying epoxy on surfaces that are very flexible such as thin silicone sheets or other rubbery elastomers. Epoxy is thermoset plastic, which is very rigid, thus does not mix with materials that desire to bend and stretch. The delamination that occurs is jagged and messy, chemistry always wins the tug-of-war. It is also a horrible suggestion to apply it to things that are subjected to direct heat such as a coaster on a pot of boiling water since most hobby resins have a low glass transition temperature. They will sink and create an uneffaceable mark, that is soul-sucking thereof all the labour.
