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Homegrown Oxidizers Part One WSM Not all of us live in an area friendly to fireworks. Access to these articles of celebration, let alone the materials to produce them may be extremely limited if not completely banned. Reliable information to produce fireworks raw materials is very difficult to find and even consulting professional chemists usually yields little useful information (unless they happen to work in the chlor-alkali industry). In these articles we’ll try to describe some workable methods of producing fireworks raw materials on a small (hobbyist) scale. The first material discussed is potassium chlorate. Industry typically produces potassium chlorate by starting with sodium chloride (table salt) and water from which is made sodium chlorate. The solution of sodium chlorate is mixed with a solution of potassium chloride and potassium chlorate (being much less soluble at room temperature) drops out of solution, is washed, dried, powdered and packaged. With a proper setup, it’s possible to make potassium chlorate directly from potassium chloride and completely avoid any sodium contamination. Fundamentals Pyrotechnists generally are concerned with the breakdown of molecules to get the required elements combined in the burning devices to produce the desired effects. To produce the raw materials desired, we need to build up the molecules. This is typically done industrially with electrochemistry. Electrochemistry uses direct current electricity in solutions of salts to create desired changes in the solutions. Examples of this are electroplating (depositing metals on other materials), electrowinning (getting pure metals from solutions), and anodizing (forming a strong protective oxide layer on aluminum). In our case we are starting with saltwater and producing an oxidizer salt. The mixture of salt and water (potassium chloride solution in this case) is changed by current through the electrodes by essentially breaking the water down to it’s elemental components, hydrogen and oxygen, driving the oxygen onto the chlorine ions (salts in solution become an ionic mixture) at the anode and the hydrogen collects at the cathode where it bubbles off and out of the solution. KCl + H2O + e- → K+ + Cl- + H+ + O- + e- → K+ + ClO- + ClO2- + H2↑ + e- → KClO3 (This is a very simplistic and unbalanced description of what happens in a chlorate cell) Many amateur chemists have made chlorates successfully using graphite for the anode (positive electrode) and iron or stainless steel for the cathode (negative electrode). Although graphite works, it has drawbacks and limitations to its use. One of the most notable is that it breaks down, leaving a black sludge in the chlorate cell that needs to be removed from the final product before it can be used. Graphite works best at lower temperatures or this breakdown is accelerated. The state of the art in industry for over 40 years uses a titanium anode coated with MMO, or Mixed Metal Oxides. MMO is a mixture of titanium dioxide and various precious metal oxides such as ruthenium dioxide, iridium dioxide and others in varying amounts to improve the electrical and physical characteristics of the coating. MMO has some distinct advantages over graphite as an anode: Though not physically tough, it is extremely electrically and chemically tough if certain contaminants are absent It can operate at much higher temperatures, improving current efficiency (CE) It produces a “clean” product requiring minimal processing to be ready for use It can operate in a cell for years, where graphite will only last for a month or so Though more expensive initially, MMO is more cost efficient due to its longevity Due to the wide use of MMO in industry, new material and surplus stock is available to the amateur electrochemist at reasonable cost. MMO on titanium anodes come in many shapes, configurations and sizes (as well as formulations). For the purpose of these articles we’ll ultimately discuss the use of an MMO coated titanium mesh anode and titanium sheet metal for the cathode (or cathodes) in the description of a workable amateur chlorate cell. Where Do We Start? Most budding electrochemists locate a source of electrodes and develop their system around them. I suggest a better approach is to locate an electric power supply and design the system around it. The best electrical practices dictate that the electrodes demand no more than 80% of the supply’s available current. Less is okay but more tends to overwork our power supply and can lead to premature failure. So what we suggest is get a power supply and tailor the entire system to it. Our power supply needs are: A steady source of “clean” DC power (little or no AC components, AKA ripple) Get as high a current output as you can afford (typically, the higher the current output, the more expensive the power supply) A variable DC power supply is excellent, especially for experimenting with various setups and conditions, but these tend to be very expensive unless a fortunate find on eBay or an electronics surplus house drops in your lap For chlorate a minimum voltage of 2.5 Vdc (volts direct current). Industry usually specifies 3.6 Vdc but we’ve successfully used up to 5 Vdc without problems Though we’re discussing voltage, the main component of power is the current. Current (measured in Amperes or Amps) is the main influence in our process and the real workhorse. The voltage only needs to be enough to keep the system working. More on the electrical theory later… Many amateur electrochemists have converted computer power supplies to the task and despite the universal availability of them; this author has never used one. Another option, if one has the electrical or electronic know how, is to rewire a microwave oven transformer to supply low voltage Vac (volts alternating current), rectify the output to Vdc and filter the output to remove AC components to yield the required clean DC power. As most computer power supplies output 12 Vdc and 5 Vdc (our interest is the 5 Vdc portion) and are capable of supplying 30 Amps we will discuss a simple chlorate cell using these parameters. The chlorate cell information shown can be scaled up or down but scaling up will get more complicated and require tighter control of the minute details of the system. To start, by all means, let’s keep it simple… Getting Started We have a power supply (5Vdc, 30 A), now we need the rest of our setup. At a minimum, we need a cell body and the electrodes. The cell body or reaction chamber needs to be compatible with the materials that it’ll be exposed to and secure enough to contain them without spilling or breaking. In the process of converting salt water to chlorate the steps include hypochlorite (bleach) and hypochlorous ions, with chlorate as the next step. The actual chemistry is quite complicated with many changes happening simultaneously and all affected by each other and a multitude of other factors. These processes have been the subject of scholarly doctoral dissertations but we’ll simplify it with descriptions of practical applications and rules of thumb to be successful (even if we don’t completely understand what’s happening we can still make it happen,… and optimize our yield). The Reaction Chamber (RC) Few materials are compatible with our cell but fortunately some of them are common and fairly inexpensive. Glass (some but not all will work) PVC plastic CPVC Teflon or PTFE Kynar or PVDF Viton rubber Typically these materials and similar are completely inert to the cell liquor we’ll create. Other materials can be used but may experience some degradation unless precautions are taken to prevent it (or they’re deemed to be acceptable losses). PE or polyethylene PP or polypropylene XLPE or cross-linked polyethylene Silicone rubber With few exceptions we’ll avoid metal containers. For example, some metals would be useful for one of the components but unsuitable for the intermediates. Glass is attractive because one can see what’s happening in the cell. Seeing is educational when starting out but not required for the process to function correctly (industry uses completely opaque cells, for example). If temperatures are kept in check, PVC is the least expensive option for a reaction chamber. We’ll discuss this more, later. The author’s first successful chlorate cell was a one gallon glass pickle jar with a 4” PVC pipe cap used for a lid and three holes drilled in the lid for 1) a vent, 2) the anode, and 3) the cathode. The setup was not ideal and a lot of lessons were learned in the process, but it made several kilos of potassium chlorate crystals that summer. The first run didn’t produce much chlorate but after recharging the depleted liquor with potassium chloride, subsequent runs produced a lot more. The reason the yield of the first run was small is the bulk of the energy went into creating the precursor ions (hypochlorite and hypochlorous, as well as chlorate) which stays in solution. Once the precursors are developed in the initial run and the liquor is charged with a new batch of chloride, the following runs produce more chlorate and right away. The anode was an MMO coated CP (commercially pure) titanium rod from a commercial source. The cathode was a CP titanium tube. The spacing wasn’t ideal, the vent was minimal and the power was low, all besides no controls and low efficiency (maybe 40%-50% at best), BUT… it made lots of potassium chlorate. It should be mentioned, only potassium chlorate was ever produced (the author has yet to bother with sodium chlorate since the potassium salt was the end goal). The whole notion of making potassium chlorate began with the discovery of the availability of potassium chloride water softener salt at the local hardware supply store. Several problems were noted during those initial runs many years ago: Lots of salt crust (salt creep) forming around the lid and around the electrode holes The electrode spacing was not optimized The electrode sizing wasn’t optimized either The power supply was under utilized Salt creep affected the electrical connections adversely The power connections to the electrode leads (alligator clips) were inadequate for the job No cell parameters were measured or controlled The whole thing was a rough attempt… but successful! Since that time, the author has come a long way and overcome these issues. We will show methods and techniques in an attempt to help the novice electrochemist bypass a lengthy and difficult learning curve to successfully build and operate an effective and efficient chlorate cell.

New design, new body, a bit advanced fuel. Turn up the volume!!! slight issues with the start that I have to figure out - but could not be happier - almost everything worked. By gps, 1km distance was travelled. Next test - will improve launch platform and will use slightly smaller diameter stainless steel tube + integrate camera.

Homegrown Oxidizers Part Two WSM The Anode A key to modern chlorate production is the MMO anode. These were hard to come by many years ago, but now are so common that surplus material can be had at reasonable cost through careful searching. Part of the success of these MMO anodes is due to their large surface area (on a microscopic scale). The typical process of manufacture involves multiple coating and baking cycles that leave the microscopic surface looking like the cracked mud of a dry pond. These “cracked mud” layers provide much more surface area than a smooth surface would; so much so that an expanded metal mesh coated with MMO has about the same surface area as a solid sheet. This is important when calculating the size of anode required for a given power supply and cell size. A photomicrograph showing the “cracked mud” surface appearance of the acid-cleaned surplus MMO on titanium mesh (200x magnification). MMO on CP titanium mesh anode material. Surplus stock is shown on the left and new stock on the right. MMO anode material; Top on solid CP titanium wire, Middle on niobium with a copper core (the bulb on the end is epoxy resin, which didn’t hold up long in an active cell) and Bottom on a thin wall CP titanium tube. MMO anode material; Top Two: on CP titanium ribbon, roughly 1/4” wide by 0.025” thick, and Bottom: a CP titanium mesh anode, spot welded to a filled CP titanium tube for the electrical lead. The MMO coating is more electrically conductive than the titanium substrate under it, so there’s no need to remove the coating for making electrical connections. The surplus MMO anode mesh material is usually from industrial sources and may often be covered with contaminants. One sample had iron oxides on it (a brown smut on the surface), which was removed by soaking in hydrochloric acid (pool acid) for 15 to 60 minutes and then rinsed with water to remove the residual acid and air dried, leaving the surface clean and undamaged. If this condition exists on any MMO material found, avoid rubbing or abrading the surface with anything. Let the acid do the work; the MMO coating is not harmed by it. If there are scratches on the MMO surface, the exposed titanium is unharmed by exposure to the cell liquor (electrolytes). Titanium, being what is known as a valve metal, is prone to passivate or “self-heal” with an insulating oxide layer when scratched. Aluminum shows similar characteristics, but is unsuitable for exposure to the conditions in the cell. The Cathode Cathodes (the negative electrodes) can be made from many different materials, due to an effect called cathodic protection, as long as the current flows. The better materials to use are known as valve metals due to their physical and electric properties, but of these we’ve chosen CP titanium for its outstanding performance in our tests. The acronym CP stands for commercially pure and it works better than alloyed titanium for our purpose (and is unlikely to add unwanted metal ions to our electrolyte). CP titanium sheet metal stock for cathodes. Stainless steel is used by some electrochemists for a cathode, but we prefer to avoid contamination by nickel, chromium and a host of other alloying metals, especially when the electrodes are exposed to the electrolyte with the power off. If electrodes are left for long periods in the electrolyte without power they break down, not unlike a battery discharging, where irreversible damage can occur. Even with titanium electrodes, if the system powers down, remove, rinse with water and store the electrodes in a safe, dry place for the best care and longevity. Single or Double Cathodes, and Why? A pair of single electrodes with filled tubular titanium leads, offset for proper spacing of the PVDF compression fittings in the lid of the cell. PVDF nuts were added because the cell lid is thin plastic. Most beginners to electrochemistry use a single anode with a single cathode. The bulk of the work is done by the anode, and if coupled with a single cathode, the anode is used at half its full potential usefulness (one side instead of both). By surrounding the anode plate with cathodes, like a sandwich, the full potential of the anode can be utilized. An experiment where cathode plates surround the anode, and with close spacing for efficiency. PVDF (Kynar) compression fittings sealed the titanium tubing and prevented any “salt creep”, so there’s no damage to the electrical connections. The tubular leads were filled with lead-free solder and ran cool enough that no heat damage affected the plastic fittings. Are double cathodes always preferred? No, but more work can be accomplished in a smaller space this way and it’s a consideration. Most of the electrodes shown so far are somewhat rectangular in shape, and later research showed that longer and narrower electrodes which reach deeper into the cell tend to enhance the effect we call “hydrogen lift” which aids the mixing of ionic species in the cell plus prevent thermal layering, and thereby making a more efficient and effective system. Hydrogen lift is a convection-like current caused by the hydrogen bubbles rising from the cathodes as the cell runs. This fluid flow draws dissolved material from the lower parts of the cell and carries it upwards to the surface of the liquor, where it flows outward and cycles downward away from the electrodes. As it nears the bottom of the cell, it’s drawn toward the electrodes to continue the cycle. This physical circulation improves the efficiency of the cell and helps to promote (along with the pH) the “bulk reaction” spoken of in technical literature, where the chlorate ions are created throughout the cell rather than just at the anode by “brute force” of the electrical current. When we surround the anode with cathodes, the electrical stresses are more uniform on the anode, and almost the entire surface is working to produce the desired products. Sizing the Electrodes When we know the surface area of our anode, we can calculate the current demand of it. To calculate how much current our anode will use, we base it on the average demand of 0.3 Amps per square centimeter of surface area. Since one square inch is equal to 6.45 square centimeters we can figure our required current with this formula: A = In2(6.45)(0.3) Where A = maximum Amperage demand and In2 = surface area in square inches That is, if our anode measures 1.5 by 6 inches (9 square inches or 9 In2) and we’re using one cathode about the same size as the anode, plugging this figure into the formula above shows us the answer 17.415, or an expected current demand of 17.4 Amps, maximum. If we sandwich the anode between two cathodes, we double the current drawn and the formula is: A = In2(2)(6.45)(0.3) = 34.83 or nearly 35 Amps If we follow the best electrical practices, we load our power supply no more than 80% of its capacity, so we’ll need a power supply capable of supplying 44 Amps or more (or 22 Amps if a single cathode is used). Going the other way, if we have a power supply with a maximum output of 60 Amps, we want our anode to demand no more than 80% of that or 0.80 x 60 Amps = 48 Amps. If we want to determine the area (in square inches) of an anode that will demand 48 Amps we use the formula: ___48A___ In2 = (6.45)(0.3) for a single cathode, or 24.8 In2 ____48A____ In2 = (6.45)(0.3)(2) for double cathodes, or 12.4 In2 We then decide what width (in inches) our anode will be and dividing the square inches by that number will give us our anode length (again, in inches). Electrode Spacing This topic has been the subject of much debate among amateurs for many years. Some believe the anode and cathode should be as close as possible without touching each other, and others believe they should be as far apart as possible within the limits of the cell container. Most amateurs seem to compromise at somewhere in between these extremes. We’ve observed several of these techniques and see that they all work; the electrolyte is conductive and the current flows. The difference is in the efficiency. The further the electrodes are from each other, the higher the internal cell resistance seems to be. There is always some resistance which is normally exhibited as heat, or “wasted energy”; but in this case, heat actually improves the performance of the desired reactions so it’s not all bad. Higher heat is really a good thing here, but not too hot. Industry uses very close electrodes, but they control the temperature actively with water cooling, flowing through hollow electrodes. Almost all amateurs depend on passive cooling, where control of the cell temperature is by limiting the electrode size and the current supplied. If the temperature goes too high, the real concern is boiling the electrolyte and warping the electrodes till they touch each other, possibly shorting the power supply, which can destroy it. We never want to allow the electrodes to touch each other when power is applied. The effect on the power supply can be catastrophic. Temperatures should also be within the limitations of the cell’s structural materials. Our best performing tests using double cathodes show that a spacing of about 1/8” (or 3mm) seems very effective. The cell ran at 55°C (131°F) and performed quite well. Spacers made of compatible materials, with insulating properties, can be used between the electrodes to stabilize them and keep them from shorting out electrically. Meters Digital panel meters to display the voltage and current output from the power supply or as it enters the cell. To monitor the power used by our system, we use meters. Either analog or digital meters can be used. The voltmeter is wired parallel to the power supply output leads (minding the polarity, i.e., positive to positive and negative to negative) and the ammeter is wired in series with the negative lead through a device called a shunt. The shunt passes all of the current to the cell, except a tiny limited portion which the ammeter measures to display the actual current flowing though the leads. Temperature is another value worth measuring and displaying. If the thermal sensor is exposed to the cell liquor, it won’t last long, so it needs to be protected. Some sensors can be purchased that are Teflon coated and will hold up perfectly in the cell environment. Building a PVC Cell Tank (RC) The most common and least expensive material to fabricate our reaction chamber of is polyvinyl chloride, or PVC. It’s available in pipes and tubes, sheets and a host of other shapes and sizes. It also comes in different colors (including clear) for a price. The simplest tank is made from pipe and fittings, though in larger sizes the fittings can be very expensive. We’ve found that closing the bottom of the tank with PVC sheet material is much more cost effective, and when properly done, a permanent fix to the problem. Typically we look for sheet stock that is about the same thickness as the pipe wall. The pieces are cut and prepared to have the closest fit (without gaps or as close as possible; minor gaps can be filled) and then glued or cemented together. Companies that make PVC glues make them generally for three industries: pipe and plumbing, industrial and chemical. Our best results have been with the industrial or chemical grade glue. Thick walled plastic pipes glued to plastic plates for a reaction chamber. PVC and CPVC are about the same to bond and glue. The CPVC handles greater temperature extremes but costs many times more than PVC. Study and practice have shown us that smaller pieces are much easier to glue together than larger pieces. Large or thick pieces need to have several coatings of glue in a short space of time to soften both pieces before bonding them together. We recommend a heavy bodied cement with medium set for the best results. Weigh or clamp the pieces being bonded till they fully set. The bond is usually permanent in 24 hours at 70°F (21°C) or above. We’ve used additional cement to fill gaps and reinforce joints by applying with a disposable plastic dropper and drying for another 24 hours between every application. Care and patience makes for a neat job and a good bond. A technique we’ve used to seal the cell lid with pliable soft tubing to help alleviate “salt creep” at the lid’s edge. For the lid of the cell we use more sheet PVC. It’s useful to make the circular lid slightly larger in diameter than the outside diameter of the tank so it’s easier to grip. To create a soft seal on the cell lid (as shown in the photo), we first cut a thin ring of the same tube the tank is made from. Then cut the ring so the ends can overlap. Determine the amount of the ring to remove so when the ends touch, the ring will fit inside the tank with just enough of a gap for the seal to squeeze in and fill. Cut to remove that measured portion of the ring, leaving the ring in the shape of the letter “C”. Next we mold the prepared support ring by heating it gently with a heat gun till it softens and becomes pliable at 275°F (135°C). Form it into a ring with the ends touching and one edge as flat as possible (the one that will be glued to the lid). Be careful not to scorch the ring by keeping the heat gun moving in circular movements and avoiding getting the heat gun too close while doing this. This technique takes practice and patience (it may take between 5-10 minutes to do this procedure and it’s best not to rush), but good results are worth the effort. The formed ring can either be air cooled, or rags wet with cold water may be used to cool the PVC material till rigid again. Then center the support ring on the lid and glue it in place. The gasket is made from silicone tubing by cutting enough to make a ring that closely fits the OD (outside diameter) of the support ring on the lid. The ends of the tube are joined together by taking a short length of the same tubing, splitting it lengthwise, rolling it and inserting it in the ends of the seal to form a hollow O-ring. This O-ring seal can be bound to the cell lid with silicone caulk, which is left alone to fully cure. The caulk remains pliable in use and can be removed later to replace the seal if necessary. It’s a good idea to slightly chamfer the top inside edge of the tank so the seal will go in easier when the lid is closed on the cell. The Bucket Cell For simplicity and availability it’s hard to beat common 5 gallon buckets. When the bucket wears out, replace it for a few dollars and keep going. It’s prudent to place the polyethylene bucket in a secondary container, in case the bucket fails. A throw away plastic pan like those used to mix concrete for cement patching or post setting makes an excellent low-cost secondary containment. It should be large enough to hold the entire contents of the bucket. The bucket lid needs to be modified by adding a bucket cell adapter (or BCA) to hold the electrodes and other fittings. Usually the BCA is fabricated from PVC (polyvinyl chloride) plate or sheet. Various holes are drilled and tapped in the BCA for standard pipe fittings (NPT, National Pipe Taper) and either plugged or filled with the appropriate fittings. To attach the BCA to the bucket lid, compatible machine screws can be used. It’s useful to put a gasket between the lid and the BCA to prevent salt creep getting through. A bucket cell custom fabricated for a fellow enthusiast using 3/8” thick clear PVC plate for the BCA (bucket cell adaptor) with several ports drilled and tapped with common pipe threads and plugged. The BCA (shown above) has the PVC plate mounted below the lid with a Viton rubber gasket (which is compatible with the electrolyte) between the lid and the BCA, in hopes of sealing them. The bolts and washers are stainless steel, and they’re mounted to threaded holes halfway through the PVC plate (so the metal isn’t exposed to the cell liquor). The BCA is made from clear PVC only because that’s what we had on hand (the typical opaque grey or white PVC works just as well and costs less), and we’re hoping it helps In observing what’s going on inside the cell, though it’ll likely be clouded with condensation from the warm cell liquor. To cut the bucket lid we simply used a pocket knife and followed the edge of the ridge molded in the plastic, till the knife cut through. The BCA is sized to be a tight fit inside the larger ring in the bucket lid. If your bucket lid is flat, a square BCA would work also. Generally, one should put in as many tapped holes of the appropriate sizes as possible. There are always more things to add, measure or monitor as our experience grows. Tubular Electrode Leads, a Boon to Amateurs Most sellers of ready-to-use electrodes sell them with flat straps for the electrical connections. These are convenient if the cell top is open, but sealing them into the lid is a major chore, and often leaks appear when the cell is in use. The solution to this problem first appeared in the APC forum blogs by the individual known as “Swede”, in the blog site called, “You'll put your eye out...”. In there, Swede shows the techniques of how he built electrodes with tubular leads, with complete descriptions and a lot of photos. Tubular leads have the distinct advantage of being able to be securely sealed in compression fittings, which will eliminate the problem of “salt creep”. We recommend using Kynar (PVDF) compression fittings, which are as compatible in our system as is Teflon, but at about one fifth of the expense. The fittings need modifying to function this way but simply drilling through them (without the seals and nut in place) with a drill close to the size of the titanium tube works. Then replace the seals and nut. Tubular leads can be connected to the electrodes by several methods, but the most effective means we’ve used is by resistance welding (also called spot welding). The most afford-able equipment we’ve found to do this was purchased from Harbor Freight Tools Company when they had a sale (about $160). The leads can also be attached by riveting or screws, if the fasteners are also CP titanium (but they’re hard to find and may need to be fabricated). Electrical connections to the electrodes are made by either tapping the top end of the titanium tube to accept machine screws (to hold the ring terminal terminated leads from the power supply) or by inserting brass or stainless steel “all-thread” (threaded rod) into tapped holes in the metal filler (solder in the titanium tube leads) and attaching the power by ring terminals on these leads (held in place between washers and a machine nut) as seen in the photos above. Electrolyte Preparation To prepare the electrolyte we need to dissolve the salt crystals and nuggets in water. Due to impurities and additives in tap water, it’s best to use either distilled water or water purified by reverse osmosis (RO) to make our electrolyte. Filtered rain water can also be used. It’s a fact that moving water dissolves the salt seven times faster than still water. Whether moving the water by stirring or by pump, the effect is the same. Heating also works, but take care not to dissolve too much salt in the water; about 350g/liter maximum is ideal at room temperature (a bit less is okay). The following solubility charts will give you the optimal amount of salt in solution for a given temperature. Some Solubilities in grams per 100 ml water Compound--------------------------- 0°C 100°C KCl or potassium chloride---------- 238 567 NaCl or sodium chloride------------ 357 391 Solubilities of salts in grams per liter We should use starting materials as pure as we can find. Even if our salt is impure, it’s better to use pure water to make our electrolyte to limit the variables in our final product. Impure salt can be dissolved, filtered and recrystallized to purify it. We still use the potassium chloride (KCl) water softener salt for our salt source but there exists agricultural sources as well (muriate of potash), which definitely need purification before use in our electrochemical cells due to impurities naturally occurring or added to it. Again, any impure salt can be dissolved, filtered and recrystallized to purify it. Bibliography, Where to Learn More… - APC (Amateur Pyrotechnics and Chemistry Forum), http://www.amateurpyro.com/ especially the Chemistry section and Swede’s blogs - Science madness, http://www.sciencemadness.org/ especially the Technochemistry section - CHLORATES AND PERCHLORATES: THEIR PRODUCTION, by James Finckbone American Pyrotechnist Fireworks News Volume 7, Number 6 June, 1974 - Industrial Electrochemistry by C.L.Mantell, 1931 - Electrochemistry, Theoretical Principles and Practical Applications, by G. Milazzo 1963 - The Encyclopedia of Electrochemistry by C.A. Hampel 1964 - Industrial Electrochemistry by D. Pletcher 1982 - Electrochemistry in Industry by Brett 1994 - Electrode Reactions in the Chlorate Process (Doctoral Thesis) by A. Cornell 2003 - Influence of the Electrolyte on the Electrode Reactions in the Chlorate Process (Doctoral Thesis) by L. Nylen 2008 A Few Sources of Supply: - U.S. Plastics Corp. - http://www.usplastic.com/ 1390 Neubrecht Rd. Lima, OH 45801 USA (800) 809-4217 - Ozone Solutions, Inc. - http://www.ozonesolutions.com/products/Ozone-Compatible-Fittings 451 Black Forrest Rd. Hull, IA 51239 USA (712) 439-6880 - McMaster-Carr - http://www.mcmaster.com/ 600 N County Line Rd. Elmhurst, IL 60126 (630) 833-0300 or check for local listing

Large Case Formers! Do you really want one? Well, if you do and don't have a big lathe maybe these ideas can help you. I had a smaller cheapy lathe that I bought from a big box store. They don't sell them anymore and I burned mine up trying to make a former that is larger than an 8 inch'er. I contemplated what to do about this and I came up with a solution that went sideways...literally. Instead of laminating blocks of wood and machining them round I decided to take flat sheets and cut them round. Doesn't make much sense does it? Well it was actually a pretty nice project and the formers work really well. So I'll do a little explaining on how I did this pretty cheaply. My first decision was to use MDF board that is 3/4" thick. I sawed a bunch of MDF into round discs. Then I lightened them up a bit and finally glued all the sections together. So one section looks like the pic below and you can make and glue as many as you want for the length desired. I bought the material new but you could maybe find cheap furniture made of this stuff to use as a donor. This is one section of my 12" former. Maybe now you are getting my meaning! Keep reading to see how I made these formers. The smallest former below is an 8" that I made on a lathe. The other 2 are an 8" and a 10" that I made using the MDF material in this blog. First of all I had to come up with some inexpensive tools to do the job. I found a band saw on Craigs List for $25. I gave it a little attention by getting a couple of new blades for it and adjusting the guides pretty tight. I also changed the table top so that I could clamp a fixture board where ever I needed to. For the fixture I merely cut some material out of a board in kind of a rounded slot. Then I strategically drilled a 1/4" hole so that I could cut the radius I needed. Clamping the fixture to the table top gave me adjustability. Not really an ideal setup but it worked. Be sure to take your time with a new blade to cut the discs. Any forcing of any kind will not cut nice round discs! So what I did was I bought the MDF and I cut the sheets down to square pieces that are pretty close to the finish size of the former. For my 10" I believe I cut the MDF into squares that were 9-3/8" which is an 1/8" over a standard 9-1/4" former dimension for making a nominal 10" firework cylinder case. Then I took a straight edge and drew a line from corner to corner in both directions to find the center of each square. The next photo is a practice piece to see how well this project might work. I used the piece above for a top and another for a bottom. The build was looking pretty good so kept cutting. Before I got a bunch cut I used the center mark to swing an arc to find 3 evenly spaced points where I continued to hole saw out 3 holes from each disc for weight reduction. What I don't have a picture of is when I glued all the discs together. Take great care in this step to keep the discs clean for final assembly. If the discs have debris between them they might have air gaps between the joints. The center hole that I used is 1/4". After applying Titebond glue or similar to each disc I threaded them onto a 1/4" round dowel. Once all of the discs were thread together I put the stack in a press and applied light pressure to laminate them together without air gaps between discs. Take care to keep well away from the center hole with dowel when applying glue. The dowel hole can act as a vent when done. The catch is that you need to be able to remove the dowel after the glue sets. When I made both my formers I was able to remove the dowel from the center hole. After the glue dried I sanded to a slight taper and tried the former. Once I was happy with how they functioned I stained them with what ever I had on hand. Then I finished them with spar varnish which is a marine application. Spar varnish also has a little bit a flex to it for expansion and contract for when the MDF gets wet and dries. I never get my large formers that wet so they have not deteriorated in any way. After a several years of use I never regretted making them. Pics of the finished formers: