Screen Printing and Strip Casting a Thermoelectric Module or Thermocoupler

I have recently seen a few things that sparked my interest in this subject, again. One was a the Canadian girl who made a flashlight to work from body heat.



This could have been done using a thermocouple and a voltage booster as shown here:


This got me thinking about how to build and construct the actual thermocouple.

The basic idea of a thermocouple is that two different types of conductive metals that are put in contact with each other will create electricity when heated. Since the metals aren't creating the electricity, the heat is, then somehow electrons flow through the metal which can be read and potentially harnessed as in the case of the led lights shown above. It's not much electricity, but this method is commonly used to create thermometers and even some waste energy retrieval systems. This Seebeck effect does not require electricity it is almost mechanical from my standpoint.

I have had a couple of problems relating to my frames in that they seem to generate heat on the top surface when exposed to the sun. Also I have been using plaster inside to stiffen these pieces which has been working as a cooling surface, which is almost in direct contact with the exterior, except for a few veneers. The flashlight and voltage booster shown above seem to have a thermocouple embedded in a tile that transfers the heat from the top surface through and to the thermocouple. From there the electricity is fed to the led light with some regulation and boosting to get the voltage to where the led light can operate. I don't think I can make anything as efficient as the ceramic tile and I am not sure if the thermocouple inside the tile is complex or simple, but I have seen that some of the thermocouples shown online are basic metal wire wrapped around each other and heated, which also means this should work as a flat contact. There are some homemade thermocouples that are linked in series and others that generate electricity to run a fan when they are placed on a wood stove. I haven't seen much detail about thermocouples that work from the heat generated from the sun, but if hand heat can create a flow then the heat caused by reflecting sunlight should generate that much heat as well. Ideally if the heat is generated over a larger flat area then it may be enough to actually read on a meter and then theoretically do something.

I purchased a thermocouple from Grainger and could not get it to generate a current when I put it in a toaster oven. I have also started coating some surfaces with metals to see if I can get any sort of current between them. This also reminds me of electrolysis which is something you don't want on boats in the water. Electrical currents can be created between vessels of different materials like an aluminum hull parked near a steel hull and if there is any corrosion the salt water allows a current to flow between the vessels like a large battery. The end result is that the electrolysis wears away the metal causes a leak or worse. I imagine the same thing can happen in buildings when they are constructed with different metals being attached as the contacts could create electricity and that could also cause corrosion over time.

My problem has been to simply put together the pieces so that I can feel confident that I am going to get a current out of the different metals with the low amount of heat that I am going to be able to apply. I am not sure if the cooling surface below the exposed metals is also relevant or not, as it seems to be with the tiles around the thermocouples mentioned above. Heat flows to cool, which is the absorption of the energy from the heat and that converted energy can be electricity in the case of the differing metals connected to each other. As electricity will flow towards the path of least resistance then the contacts and cool surfaces are providing a direction for the heat energy to go. Heat is not directly electricity, so electrons must be getting released between the two metals which seems to go through the metal creating the current. Assuming I have this kinda right, then if the contact spaces are larger then the reaction can create a cumulative effect as long as the energy has a place to go.

This is where I am confused since all of the pieces I see are concentrating the effect on small rod light devices or wire that comes to a point. These types of thermocouples are devised to make an easy transition from the couple to the wire and therefore the path of least resistance is clear and the wires are treated like a positive and a negative. I am not sure how you decide what is positive and negative, but the underlying theory or Seebeck effect seems very simple with the metal wire and direct heat. The air around the wires may be the cooling element with the exposed wires and therefore the amount of current being created is less than with the ceramic tile effect, but for me any current would be neat. The cooling area or contact area may be a surface that simply pulls the heat into the surface and then the wires and metals are able to conduct the heat and transform it into loose electrons. That's the best I've got so far and the only metals I have are aluminum and steel. I am trying to figure out what pattern to use for the contacts and if the contacts need to be limited to a small area or not.

Never a dull moment when screen printing thermocouple electric generators

It's a dream more than a reality, but I am getting ever closer to making something useful. This time I am attempting to convert some of the frames I have reclaimed into electric generators using a thermocouple concept known as the Seebeck effect. The basic concept is that dissimilar metals when connected and exposed to heat can generate electricity. Whaaaaat? My concept is to merge art with science and use my frames at the same time. All I have to do is print the conductive metals so that they can be exposed to heat, sunlight, and then get the contacts and flow arranged in such a way that an electrical current is established. The details will follow, but in the meantime it's one small step for photo-fresco and large step forward for screen printing technology.

Lessons learned is logic lost

I just like to make up titles that sound good, then try and apply some logic. I keep thinking I am learning stuff and progressing with my experiments of epoxy, screen printing and faux fresco techniques, but when it gets down to it I just push forward with the things that are closest to me. I find myself working in a daze sometimes, just printing and mixing and slapping things together. The only logic that seems left in this is that I have gone to the trouble of putting things around me that I think will work together.

The variations on the types of things I have been making keep me running in circles with finished products. Each time I get close to something finished, like a pendant or emblem, I think that the finishing steps are too cumbersome and I trash the concept. What seems to be the problem is that I don't want to make things that are not going to keep being fun to make once I figure them out. I like figuring them out, but sanding and applying adhesives to make pieces into something useful like a key chain or sticker keep pulling me down. The larger products like prints and framed pictures are difficult to carry, display and sell, but these types of pieces seem easier in that when you are done with something it holds itself.

I've taken to spray painting the edges of frames to make the finished prints on frames even easier to give a slight sense of finished without attaching a frame. I can't say I am a huge fan of that technique, but it works, it's cheap and it's fast. My last batch of screen printing frames converted to printed frames are still being finished, but I did get an assortment of techniques into a finished set of pieces by doing some down and dirty processes.

First I cleaned and scraped the ink and residue off a bunch of old screen printing frames using a putty knife, mineral spirits and rubber gloves. After they dried I put some tape on the inside to block the design and then put a couple of coats of some old latex paint over the emulsified screen without trying to clean out the emulsion or remove the design, I just painted over it. After two coats I removed the inside tape and put a coat or two of paint on the inside of the frame to seal off the emulsion and screen, as well as, to cover any ink residue left on the inside of the screen. This provided me with a white flat surface on the topside of the screen to work on.

I'm not sure how well the latex will hold to the emulsion on the screen, but since the latex is going to be covered I am thinking that it won't be subjected to significant abuse. This process provided me with a batch of 10-15 frames with a flat white surface that is essentially primed with a gesso like coating. I wasn't super pristine in my work so there are some bumps from left over tape and ink, but I am trying to keep the labor down and be able to do this job without thinking too much. If I was outside looking for a piece of wood or flat surface to work on this would be ideal, so although it may not be up to the standards of a professional art canvas it's better than a scrap of wood or rough cement surface.

I have been applying a batch of techniques to these frames from direct printing onto the surface with a variety of screen printing inks and epoxies. I have also used them to apply vinyl adhesive backed prints to, large stickers basically. Each of these techniques showed promise, but the idea of working on the frames and the prints separately has merit. I also created s a rusted surface directly on the frames and I have a few of those sitting around that I can now try to print directly on. The benefit of working on the large vinyl stickers is that I don't have to be committed to the work while I work on it, because I don't have to think that I am wasting a frame if I don't like it. Cleaning the frames is more work than what I do to make a design, so I have an added mental investment in a piece being done directly on a frame that may keep me from testing techniques. Also the difficulties in printing on the surface of the frame itself are a little bit of a problem. I have been using spray paint stencils for a final coating on the image part of designs and that eliminates the problems with printing.

Some of the techniques I've been using are things that I hate, like splattering around a design. God I hate that, but because I am so sloppy with the epoxy it has dripped from time to time onto the background and there is no way I can even begin to think about getting it off, so I have had to just add a few drips around it. Once again, I hate this look, but aesthetically it does look more finished than some of the pieces that just have an image floating on the background surface. It is like I hate using artistic techniques that will appear arty even if they work. I am trying to make something that is as if it came out of a machine, with no feeling besides the texture and the graphic, but these cheesy methods like splatter seem to make the image come together, which makes me hate it even more because I can't escape it. Spilling paint is something I can do, but I don't like to think of it as a skill or something that I meant to do or it destroys my whole process of industrial design. I am interested in how people perceive it and if pieces are more attractive to the viewer because of these painterly accents.

Powder Coating and Powder Metallurgy and Powder Painting

Powder Coating and Powder Metallurgy are base industrial processes for coating metal and making materials with powder metals instead of the standard painting methods. I've been playing with metal pigments in different materials and making a faux photographic process using steel, which rust, for the lighter tones of an image. Ideally the pigments provide a more resistant surface for weathering than do epoxy, acrylics or resins by themselves, but that would only be true if the rusting process stops. I haven't bothered to apply a top coat or sealant to the oxidized surface because I don't want to change the look and feel of the light rust. Is there a state of oxidation for metal when it is stable as rust, which would mean that I am just making yellow metal?

I have iron oxide yellow available as a color, but it does not have the depth and shades that putting a layer of steel and watching it rust has. The mystery just isn't there if I start with the final color. This is the way in which this process is sort of like photography. With photographs it is always a mystery when you put the paper in the developer and watch the image appear while the chemicals react with the exposed paper. The same is true when I coat a layer of steel with wet salt and wash it off. The lighter steel coated areas slowly appear more and more yellow as they dry and create a contrast with the black areas.

I have started making whole sheets of vinyl sticker paper coated with steel and oxidized as a substrate for printing or spray painting on. I am not sure if the process is worth it, but it does have potential for making a bunch of sheets in this way that I can use later and not have to keep going through the task of making the rusted metal sheets every time I want to use this process.

My first idea was to use wood for the substrate, then I switched to canvas before I moved to vinyl sticker paper. Vinyl sticker paper is not exotic or fancy in any way, but when I think about the potential applications I consider it a very versatile substrate. The designs and printing methods I use only make a thin layer or veneer that is the image in a graphic. Substrates like canvas, wood, cement and plaster are holders for these materials to give them body and strength. I like some of these materials, but each one of them then has to be put into something or finished in a way that would make them useful and that takes additional time that often feels like more work than making the pieces themselves.

I like making images, but don't like making finished things. This has always been a problem of mine. In college I used butcher paper for screen printing and my teacher ignored my work. In photography lab I didn't matte my prints in the standard way and I was blocked from the group exhibit with the rest of the class. This is of course why I liked the punk rock aesthetic when it rolled around and the idea of zines and such. T-shirts only work for me because they are somewhat finished and I am just adding a design on top. The problems associated with framing and mounting are by and large too much for me to keep working on designs and sticker paper will allow me to print and cut or file the work and not worry too much about the final touches. As stickers these types of prints can also be used by others in a quick way, although I am not sure how this would help the value of the work.

The main difference and problem with vinyl versus paper or another medium is that the layers cannot penetrate the top surface and bond with the substrate in the way that materials and pigments embed themselves into canvas, plaster and paper. The entire bond with the vinyl is contained in the chemical hardening on top of the vinyl and then the pigments being layered into and on top of the vinyl paper. I have been able to remove a thin layer of epoxy and other materials from the vinyl like a flexible layer of latex, so these pieces are literally only skin deep. But versatility over substrate is my call to action today. I can always make these pieces on thicker mediums and more permanent objects later. For now I am working on vinyl as if it was a fine quality archival substrate like the finest rice papers from Japan.