I. Materials: 

The minimum amount materials you can purchase will make quite a few stamps, which is quite expensive if you only need one stamp, but very reasonable if you are making many stamps. Epoxy is the most expensive material and generally the smallest quantity you can buy is enough for many stamps. You can also make many other things with this method and materials, such as ornaments, pendants, preserved insects and plants, jewelry, and other cool resin items. You can also purchase pigments and micas for the epoxy which look very nice. RTV silicone makes a good partner material if you want to replicate your stamp or sculpt and engrave a master item (like an ornament or jewelry) out of plaster or other materials, and then use the silicone to make a mould of the item to caste with resin. Have fun, but always remember to read the safety precautions on the materials you are using and protect you skin, eyes, and lungs. 

- Plaster of Paris

- Epoxy resin with regular or fast hardener (FGI R180 and H180 works the best and is clear, it can be purchased from fiberglass supplies stores or online). Polyurethane resin (often called "fast casting resin") will NOT work with this process, as polyurethane reacts with water and foams, so because the resin is poured on moist plaster the stamp will foam and be brittle. But, if you make an epoxy original and then make a silicone mould of the original, you can use polyurethane resin with the silicone mould.

- Wood or other material for stamp handles, 45x45mm pine is a good size for most stamps (it is possible to pour a handle from resin if you don't want to work with wood, explained later)

- Always wear gloves, protective clothing and a respirator suggested by the material manufacturer.

- Engraving tools: Pins, long needles, tweezers, tiny screw drivers or anything you can find!

- Accurate mixing containers for epoxy, with stir stick.

- Tub (like a butter or yogurt tub) for warm water.

- Plastic tray for pouring stamp set up.

- Container with flat smooth bottom to make the stamp engraving surface.

- Thin plastic (0.25-0.5mm), wide tape, or clay (pvc plastic is the best) for making stamp corral when pouring resin.

- Sand Paper in 240 grit and 400 grit (medium and fine grits, or whatever you have around). 


II. Methods:

a. Print design from ink jet printer


            There is a great free program called GIMP which is easy to use to size and manipulate/create designs for your soap stamps. The design needles to be flipped mirror image (horizontal flip) so that it is transfered to the plaster in the right orientation. I print my images in blue for easier transfer onto the plater. Be sure to use an ink jet printer with water based ink (most are water based, the ink will run when wet). 


b. Pour plaster and transfer design

            Mix your plaster to a think consistency as directed on the package and be sure there are no lumps (mixing with a gloved hand gives you a good feel of the smoothness) and pour into a flat plastic container with a smooth flat bottom to a thickness that will not break when popped out (about 2-4cm, some testing may be required). Tap the container on a desk to be sure the bubbles are brought to the surface. The stamp will be engraved on the surface that is moulded from the bottom of the plastic container, it is not advisable to engrave on the top exposed surface as this side is soft, not flat, has raised bubbles, and generally a poor surface for working on.
            Once the plaster is hard, pop it out of the container and sit on a towel for about 5 minutes to lightly dry the surface of the porous material. You DO NOT want the plaster to be completely dry when working with it, as it will be very hard and powdery, keep it moist while working with it, but not too wet on the surface when transferring the image so the ink does not bleed sideways.
            Lay your image face (ink side) down onto the plaster and wet a finger. Press the whetted finger into the paper with pressure so the ink soaks directly down and into the plaster. Move around the image until the whole image is transfered. You will know it is transfered when the design shows through the back of the paper, but is not bleeding. If it is bleeding sideways, reduce the amount of water used and slowly work moisture into the paper with pressure and a lightly moistened finger.  






























c. Engrave design

            Engrave your design with different tools you find around your home. It is advised to first sketch out the design where there is ink transfered before the ink fades, then go back in and slowly deepen and clean up the image. There is a limited window of time for engraving once the ink is transfered, as it will slowly begin to fade and blur. Be careful not to push the design too deep or it may break the plaster! If you have an area that is very detailed, wetting the surface with water pooling on the design while working makes plaster removal very easy, which helps in detailed areas. The plaster should always be moist while working on it so that there is no plaster dust (only little moist balls) and to make engraving easier and the plaster less brittle and prone to breaking. Needles can work well for cleaning up around the border of design areas. Periodically rinse out the design with running water and a paint brush so you can see the depth and what needs cleaning up.











*What the design looks like engraved in the plaster will be exactly how it will look stamped on the soap - so words/symbols should be readable and in the correct direction on the plaster. 







*One of the great advantages of using plaster is that you can do very accurate reproductions of text and detail, even small detail (to an extent).








d. Set up plastic corral

            Once your design is done, scratch a deep, but not too wide, trench around your design where you would like the edges of your stamp to be. Be careful not to get too close to the design, as you don't want to risk breaking your design at this stage, and you want a good border around the design (about 5mm) which serves to press down displaced soap when stamping.
             Give your design a final rinse and clean, then sit the plaster on a towel bottom down for about 5 minutes to draw moisture from the engraved surface of the plaster. Now you can set up the resin corral by cutting a 1 cm wide strip of thin pvc plastic or by making a similar strip from tape or by using clay. The pvc plastic is the bast choice for ease of use and the look of the resulting stamp will have even and smooth sides, but thick doubled over tape can make similar results, clay is the most difficult to work with as it can slide around on the plaster and be rather messy. If using thin pvc, you can put some tape around the bottom edge to give it a snug fit in the trench and reduce the amount of leakage.






e. Pour water and epoxy

              Once your corral is set up, place the plaster into the plastic tray and ensure that the design is level. Fill up your plastic yogurt tub with hot water from the tap (NOT boiling hot!). Set up for working with epoxy by applying your safety gear, getting containers ready, and having some long needles and other tools at hand. Pour the prescribed amount of resin and hardener into your measuring cup, and hold the bottom of the container with your epoxy in it into the hot water, and stir the epoxy until the heat has thinned it's consistency, and the hardener is mixed in completely. Try not to whip too many bubbles into the epoxy. Mixing the epoxy in the warm water helps to thin the epoxy to a more fluid consistency so it flows into the engraving with less bubble trapping, it also accelerates curing as the chemical reaction that occurs between the resin and hardener is endothermic. Some fast hardeners can accelerate the reaction very quickly and can seize in the mixing container and become very hot (more so if in a tall container, rather then a flat spread out container), so it is best to work swiftly.
                When your epoxy is warm, mixed and ready, pick up both your warm water in one hand and your epoxy in the other. Pour the water into the tray and the epoxy into the corral over the design at the same time. You don't want the surface of the plaster to have water on it when you pour the epoxy or it will mix with the epoxy, but you don't want your epoxy to soak into the plaster, so it is important that the water rising up through the plaster meets the epoxy at the same time. If the plaster turns a dark colour after pouring the epoxy, this means the epoxy is soaking into the plaster, which may not mean that the stamp will be lost, but is not optimal and could present some problems later. If the epoxy turns white on the bottom this means that there was water on the surface of the plaster that has mixed into the epoxy. This may make the surface soft for a while, white in appearance and extend the hardening time. Just pouring epoxy onto the plaster without water will result in epoxy soaking into the plaster and hardening in the plaster, which destroys the stamp. The water prevents the epoxy from soaking into the plaster and creates a barrier between the epoxy and plaster so the stamp can be easily separated from the plaster. This step is the most critical in making your stamp work.      
                 Once the epoxy has been poured (about 5-8mm is a good depth) there may be some slow epoxy leakage from around the corral, which is fine as long as it's not flowing out at a rate that will deplete the stamp. Ensure the water is poured to about a cm depth, but do not pour the water so that it flows over the edge of the plaster and around the stamp, this may inundate the stamp with water and damage it. Just enough water to keep the plaster moist, it is a very porous material and will wick water up quickly from the bottom to the top. If you are in a room that is cold, shining a warm lamp on it will help to speed up the cure. If the stamp is too hot though the epoxy may form tiny bubbles, so some testing may be required to find the right conditions in your house.   
                 Before you finish, check for bubbles trapped in the design and lift out with a long needle. Be careful not to touch the plaster with the needle or plaster and water may mix into the epoxy.

Make a resin handle: If you don't want to work with wood, you can make a handle out of resin. The resin handle will be easier to clean and won't be affected by water like wood, but it is not as resilient to hammering if you hammer your stamp into hard soap. To make the resin handle, simply make the corral around your stamp about 4-6cm tall (or however tall you want your handle) and pour resin up to the top. This large volume of resin will heat up much more than just the stamp faces, so I would not recommend using a fast hardener as these can get really hot and melt plastic corrals. I would also not recommend adding any additional heat to speed up the cure, as it will cure faster and hotter than a thiner layer of epoxy anyway. (example in last picture)
 

*** If you have left over epoxy and are using a slow or regular hardener, you can store the excess in the freezer right away which will slow the curing for a few days and can be taken out and warmed in a water bath later for use when mounting the stamps on wood handles.  


f. Unmould, clean, and mount

                  When the epoxy is hard (depends on your epoxy brand and type of hardener, I usually leave the stamp over night), pry the stamp up slowly going around the edges with a knife. The design of the stamp may still be a bit soft as it has been in a slightly cooler environment in the plaster. You can now remove the corral from around the stamp. Trim the rim off the edge of the stamp with a scissor to reduce the amount of sanding later, and then set flat to fully harden (usually another 4 hours).
                   When hard, use a medium grit sand paper (240 grit) to even out the design depth and smooth out the edges of the stamp. Then follow with a fine grit paper (400 grit) to smooth, and scrub the stamp with a tooth brush to clean it up and make sure there is no residue on the surface. Sand the bottom of the stamp to rough up the epoxy on the bottom so it will bond well to the handle. Apply epoxy to the wood handle and back of the stamp face, and allow to cure for 24 hours. You're done!!!  Now you can make all the stamps your heart desires! :)



























*Example of wooden handle and resin handle.





III. Troubleshooting:

- Epoxy has soaked into the plaster: Plaster is too dry and epoxy soaks in - make sure plaster is moist but not pooling water on the surface, pour water at the same time as epoxy.

- Stamp has white soft face: Water has mixed into the epoxy make sure the plaster does not have water pooling on it when pouring epoxy and pour epoxy a moment before pouring water bath. Water and plaster may have been mixed into the stamp when removing bubbles.

- Stamp is slow to harden: Too much resin (check measurements), too cool (use warmer water bath, put under warm lamp, use a faster hardener).

- Stamp is brittle: Too much hardener (check measures), too hot while curing (use cooler water bath, remove lamps or if ambient is too hot move to cooler room or cupboard).

- Stamp has soft spots that are sticky and won't cure: There are little pockets of resin that have no hardener mixed in, mix better next time, unfortunately the stamp may not be saved (although you can try to harden it by putting a little hardener on it and leaving it in a warm area for a while - just be sure to clean it very well and do not breath or touch the hardener).

- Tiny bubbles form in the design where is meets the plaster: too hot while curing (use cooler water bath, remove lamps or if ambient is too hot move to cooler room or cupboard).





NOTE: Be sure that the materials you use with and around your epoxy are not reused for other purposes, always remember "Safety First". These instructions are a guide only, it is up to the individual to take precautions and research the materials and procedures they are using, we are not responsible for any costs or losses incurred while using these instructions, they are simply to provide ideas and demonstrate methods and techniques that may be used to create stamps.