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A PRACTICAL GUIDE AND SPECIFICATION FOR PREPARATION OF 10% BALLISTIC GELATIN Introduction (by Dale Towert) Many people have written to me asking how to prepare and use ballistic gelatin. Initially I briefly described the method found in Marshall & Sanow’s book, under the heading “Tissue Simulants and Test Media” on my web page. However, Ken Couger (kcouger@aol.com) offered to send me a far more comprehensive method, and has most kindly agreed to allow me to make the text available for download. When I contacted Ken regarding publishing his information, he wrote: ------------------------------------------------------------------------------------------------------------Hello Mr. Towert: You have my permission to re-format the text and make it available for downloading on your web page if you will agree to include the following information where it is most appropriate: For ammunition test results to be of any value, BB calibration and reporting is crucial when ballistic gelatin is used as a test medium. BB shots should be made and recorded before and after the ammunition testing. Both the velocity and penetration depth should be recorded in order to adequately interpret and verify any test results. Any reporting of bullet test data utilizing ballistic gelatin that does not contain these gelatin calibration data should be considered scientifically invalid. -------------------------------------------------------------------------------------------- Materials and Equipment Needed 1. Kind & Knox, Type 250-A Ordnance Gelatin powder available from Kind & Knox, P.O. Box 927, Sioux City, Iowa 51102. 1/800/223-9244, Attn: Ms. Lanette Tackett. 2. Moulds--I use three moulds made from sheet aluminium. The mould bottom and sides are of one piece, with ends heli-arc welded to bottom and sides. Mould dimensions are: 6" wide bottom, 16" long sides and 7" tall. The ends are approximately 6-1/4" wide at the top. When the sides are welded in place the mould will have a slight draft (taper). This will allow for easier removal of the gelatin block, when cooled. Each mould also has a hole drilled in the centre of the bottom. The hole is tapped for a 1/4" X 20 screw. When the block of gelatin is chilled, by removing the screw, inserting an air hose nozzle, the block can be "blown-out" of the mould. 3. A graduated 5 litre pitcher to measure hot tap water. The pitcher I use is made of polypropylene plastic and is available from Consolidated Plastics, 8181 Darrow Road, Twinsburg, Ohio 44087. 1/800/362-1000. Consolidated Part # 4621OLE. Cost is approximately $31.00. 4. A source of very hot tap water. I use water from my home hot-water heater. Approximately 45 minutes prior to measuring out the hot water I'll turn up the temperature control to the maximum. 5. Three 5-gallon plastic buckets, with tops. I purchased these from a local fast food restaurant. Restaurants acquire plastic buckets when sliced pickles are purchased. Cost of each bucket with top was $2.00 each. Shop around for the best buy. The buckets should be clean and in "new" condition. 6. Plastic 7-8 gallon size round trash can. This container is used when mixing the gelatin into hot water. The inside surface should be as smooth as possible which will be helpful when cleaning. By using this "trash can" only one container will have to be cleaned-up. 7. Thermometer--The thermometer I use is graduated in two degree increments from zero to 212x Fahrenheit. I purchased it for around $12.00 from a local laboratory equipment sales company. Look in the yellow pages under "laboratory equipment" and shop around for the best price. 8. Cinnamon Oil--I purchased a 3 oz. container of Cinnamon Oil from a local pharmacy for approximately $3.00. 9. 1/4" electric drill and metal paint stirring device used to stir paint or wall-board "mud". I do not like to use the type with two or three flat pieces of metal spot-welded on a 1/4" rod. Metal "blades" will scratch/cut the sides of the plastic mixing bucket which will make cleaning more difficult. I use a stirring device that has a 3-3/4" circular piece of metal welded on the bottom of a 1/4" rod. The circle of metal has four 1" cuts toward the rod with the leading edge of each cut bent up slightly and the trailing edge bent down. I polished the circular edge to keep from damaging the plastic "trash-can" during mixing. This device makes for excellent "whirl-pool" generation. 10. Mould release spray--I use "Pam" aerosol in a 6 oz. size. 11. A 5"--6" square of cotton "T-Shirt" material. This is used to spread the mould release spray evenly inside the mould. 12. Refrigerator--I purchased a used refrigerator that would accommodate 9 blocks of gelatin (3 per shelf). The refrigerator must be capable of chilling moulds and maintaining gelatin blocks at temperatures of 38x-40x Fahrenheit. 13. Compressed air supply--I use a remote "plug into the cigarette lighter" compressor. It works well to "blow-out" the chilled gelatin blocks. 14. A plastic "spatula"--This is used to "break" dried, crusty gelatin at the mould top prior to "blowing-out" each block. 15. A supply of 13-gallon size plastic bags, with wire "ties" to store blocks of gelatin in, prior to use. 16. A plastic "ice-box" to transport blocks of gelatin in. I use a Rubbermaid brand in 128 quart size. This size will accommodate a total of 8 blocks. Four on the bottom and four on top. However, I usually only make up 6 blocks for a typical "Ammunition Ballistic Demonstration". When I have to transport gelatin overnight for an out-of-town workshop, I use several blocks of "Blue-Ice", to keep the gelatin chilled. The blue-ice must be wrapped in newspaper or some type of insulating material so not to freeze-burn the gelatin blocks. Crushed ice will work well for longer trips. However, crushed ice seems to lower the gelatin temperature below the desired temperature of 39.2x Fahrenheit. 17. B-B Gun--I use a Daisy Model 880. Prior to use, each block of gelatin should be "certified". The FBI certification test is as follows: "Use DAISY Powerline #880 BB Rifle with DAISY Match Ground #515 .177 Cal. B-B's shot at 590 ft/sec x20 ft/sec (approximately 5 Pumps). Shoot corner of block set at 10 feet from muzzle If block was prepared properly and chilled to the correct temperature--39.2x Fahrenheit, BB will penetrate 3.5" to 4.25" into the gelatin block. More or less BB penetration isn't desirable for comparative data purposes--the block will be either too soft (warm) or too hard (cold). Once removed from the refrigerator, block should be "used" within 20 minutes or replaced in refrigerator." 18. Chronograph--I use an Oehler Model 35P with the "short" sky-screen bar. Prior to Mixing Gelatin 1. Clean all moulds that will be used. There will probably be some dried crusty gelatin remaining in the mould from previous use. I'll use the plastic spatula to "scrape" the gelatin out with. 2. Seal "blow-out" hole in mould with a 1/4" X 20 screw which has a small o-ring gasket. 3. Lightly spray mould release inside mould. Wipe spray around with square of cotton T-Shirt. The correct amount of spray will be just enough to feel "slightly tacky--easy to feel, hard to see." This procedure will be similar to amount of lube used when handloaders lube cartridge cases. Too much spray will make for an "orange-peel" surface on the gelatin block. Too little will make it difficult to "blow-out" the chilled block of gelatin. 4. Regulate the refrigerator temperature to chill moulds to 39.2x Fahrenheit. It will usually take at least 24 hours to chill three moulds of gelatin. This may take a longer time in warmer weather depending on the location of the refrigerator. 5. Attach the stirring rod to the 1/4" drill. 6. Set-out the cinnamon oil in a handy location. 7. When the "water is hot" measure 9 litres into each 5 gallon plastic bucket. I'll pour 5 litres of water into each three buckets followed by an additional 3 litres. Since my office-warehouse is several blocks from my home I must transport the three buckets of hot water. Therefore, after 45 minutes of maximum heat the water from my home heater is approximately 150x Fahrenheit. When I arrive at my office-warehouse the water has cooled to approximately 140x Fahrenheit. This is the temperature I strive to maintain when mixing the powdered gelatin and water. Mixing Procedure Similar To The FBI Procedure. (With my comments in italics). 1. Use very hot tap water (150xF +0x,-20x). Pour measured hot water into a 7-8 gallon plastic trash bucket. (This way only one container will have to be cleaned out after gelatin has been prepared and poured into moulds). 2. Add 3 drops cinnamon oil to water to retard foaming while mixing. 3. To inhibit mould growth add 5 ml Propionic acid per litre of water. Use 45 ml total for each mould pan.(Pure stock solution obtained from Fischer Scientific, Fair Lawn, NJ or Baker Analysed #V-330-07 obtained from V.W.R. Scientific, Seattle, WA). This step may be deleted if the blocks will be used within 5 to 7 days. (I have never used Propionic acid. All gelatin blocks I have prepared are "used" within 4-5 days). 4. Spray mould pan with "PAM" or IMS "Super 33" silicon spray mould release obtained from IMS, 10373 Stafford Road, Chagrin Falls, OH 44022, for ease of removing gelatin block from mould pan. 5. Mix at 10% by weight--1 kg (2.205 lb.) Kind & Knox, Type 250-A Ordnance Gelatin powder to 9000 ml H2O (9 litres). This mixture will yield sufficient material to mould one block approximately 6" X 6" X 16" in size. 6. Always add powder to water during mixing. 7. Mix thoroughly with paint stirrer on an electric drill while slowly pouring powder into the water. (It takes me a full 60 seconds to pour the powdered gelatin into the hot water while mixing with stirring rod). 8. Slowly pour mixed ingredients into a second bucket lined with cheesecloth. Lift out cheesecloth slowly to strain out lumps. This step may be deleted if gelatin powder is thoroughly mixed in step #7. (I have never used this step. All of the powdered gelatin is mixed thoroughly if a full minute is taken to pour the powdered gelatin into the water while mixing. 9. Slowly pour strained mix into mould pan and let stand at room temperature for 4 hours to hydrate and for bubbles to float to surface of block. (There will be bubbles and foam. The cinnamon oil helps prevent foaming but some does result. It will float to the top of the mould and will mostly dissolve within 4 hours. Whatever remains will not be of hindrance anyway). 10. Place filled mould pan in refrigerator at 39.2x Fahrenheit for 48 hours (FBI instructions) before using. (Level mould on refrigerator shelf with wedges of cardboard. I'll usually remove chilled gelatin after 24 hours and prepare additional blocks as required). 11. After 48 hours in refrigerator at 39.2x Fahrenheit, remove gelatin block from mould pan (blow-out with air compressor) and place in plastic bag (13 Gallon Garbage size bag works best), remove as much air as possible or wrap with a "Saran" type of plastic to prevent evaporation. Blocks can be stored at 39.2x Fahrenheit, in refrigerator for later use. (The 13 gallon size plastic bag works best. With wire-type refrigerator shelves, use cardboard rectangles to set gelatin block on). 12. GELATIN BLOCK CALIBRATION--Use DAISY Powerline #880 BB Rifle with DAISY Match Ground #515 .177 Cal. B-B's shot at 590 ft/sec x20 ft/sec (approximately 5 Pumps). Shoot corner of block set at 10 feet from muzzle. If block was prepared properly and chilled to the correct temperature--39.2x Fahrenheit, BB will penetrate 3.5" to 4.25" into the gelatin block. Once removed from the refrigerator, block should be "used" within 20 minutes or replaced in refrigerator. 13. GOOD LUCK!
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