The term "fossil" refers to organic material that has been preserved in the earth for thousands of years. While it takes a long time to create authentic elements, you can try to make your own using plaster of Paris (calcium sulfate hemihydrate). You can reproduce the basic process of fossilization overnight by placing objects in the plaster mix and waiting for it to harden.
Steps
Part 1 of 2: Prepare the Mold Mix
Step 1. Choose the material
Although you can use latex glue, cement and even flour to make the mold, it is recommended that you opt for plaster of paris, as it is inexpensive and designed to be easy to use. However, if you are considering exposing the fossil outdoors, the concrete makes it more durable.
- A 2kg pack costs around € 4-6 and is more than enough to meet your creative fossil needs.
- Harder materials such as concrete should not be mixed in common bowls; get a container that you can "sacrifice" without problems.
- You can opt for a blend of flour or other substances such as salt and coffee for similar results.
Step 2. Combine the calcium sulfate with the water
Regardless of the exact material you want to use, make two parts of the mixture with one part of water; take a bowl and pour both ingredients. Although exact proportions are not necessary, you can use a graduated cup for this.
- For most projects, 400g of chalk mixed with 250ml of water provides all the compound you need. If the objects you want to fossilize are larger and need more space, double these doses.
- If different proportions appear on the paris plaster package you bought, you should follow these instructions; some brands and certain types of products may have special needs.
Step 3. Stir the mixture until it becomes uniform
To do this, use a spoon or a popsicle stick, working the mixture until it takes on a homogeneous consistency; when finished, it should become thick and viscous with no visible trace of chalk dust.
This is the right time to solve some problems with the consistency of the mixture: if it is not semi-solid and dense, add more chalk; if some of the powder has not incorporated, pour more water
Part 2 of 2: Creating the Fossil
Step 1. Gather the objects to be fossilized
There are an infinite number of things you can choose from to create the fossil, shells and animal bones are best for their characteristic shapes. You can also collect plants and leaves in the garden or in the nearby park; in order to demonstrate the fossilization process, you should choose something organic.
You can use plastic toys in the shape of insects and animals instead of real ones
Step 2. Smear some petroleum jelly on the object
You should use this substance to thinly coat the object you want to fossilize; by doing so, it will be easier to extract it once the chalky mixture has hardened. Scrub away the excess amount of lubricant; if you leave too much of it, it can interfere with the hardening and transfer process of the image into the plaster.
Step 3. Pour the mold mix into a paper cup, filling it to approximately ¾ of its capacity
Do not exceed this limit, since soon you will also insert the object and you must avoid that the mixture overflows.
If the fossil is larger than a glass, use a disposable bowl or paper bag
Step 4. Enter the object to fossilize
Once it has been coated with petroleum jelly, push it into the calcium sulfate mixture. You can decide whether to create only a partial impression of the sample or to immerse it completely; in the first case, you get a fossil that you can exhibit, in the second you have the possibility to play the "little archaeologist" and open the mold to reveal the shape inside.
If you are making fossils with other friends, you should start by making footprints; this technique has a better cost / benefit ratio and is a lot of fun in a group
Step 5. Give the mixture time to harden
Wait until the material has solidified before proceeding; the plaster of Paris should be completely dry within a couple of hours.
To speed up the hardening process, heat the mold at 120 ° C for an hour
Step 6. Break the glass to open it
It only served you to contain the plaster and give it a shape; once the mixture has become hard, you can throw the bowl away. Cut it with scissors or a knife starting from the top towards the base and tear it away completely from the mold; you should end up with a hard block of chalk.
- It is advisable to proceed with this phase while remaining above the garbage can; in this way, the residues fall directly into the waste and reduce the mess.
- Don't forget to throw the paper cup in the trash when you're done using it.
Step 7. Remove the object to get the impression
If you have only partially immersed it in the mixture, you should be able to detach it without breaking it thanks to the presence of petroleum jelly. Proceed gently and slowly pull it upwards with your fingers; if you are clumsy and hasty, you run the risk of damaging the print or the object itself.
Step 8. Erod the mold to give it an authentic look
If you made the fossil footprint as a decoration, you can make it look like a recent find by chiseling it a bit. Take a hammer and hit the chalk block to chip its sides and corners, adding a few indentations and imperfections. While it is not appropriate to overdo these tweaks, the worn appearance makes the fossil more interesting.
Step 9. Unearth the fossil hidden in the block using a precision hammer
If you've opted to completely submerge the item in the chalky mixture, you can play archaeologist. Take a geologist's hammer and tap the mold. Work across the surface to reveal the internal fossil; be careful not to accidentally hit the object. This experience makes you understand what it means to find and extract a real fossil from the ground.
Advice
- Recently, three-dimensional printing technology has proved very useful for creating fossils. While professional printers are prohibitively expensive for everyone but the rich, there are cheaper solutions. For example, some online groups allow you to use a 3D printer for a monthly membership fee while other educational institutions, such as universities, allow access to this technology at relatively low cost.
- The fossilization process largely represents the reason why we know so much about the prehistoric era; you should consider such details when making this craft project.
Warnings
- Clean up chalk splashes as soon as you can; if you let it harden, it becomes very difficult to remove.
- Do not pour the plaster down the drain or sink because it solidifies in the pipes and damages them; throw it in the trash.
