Repairing cracked plastic sounds like a difficult task. Fortunately, most plastics are thermoplastic, meaning they can be heated and reshaped. The key to repairing cracks in plastic is figuring out the best method to do it. Small cracks can usually be repaired with glue, hot water, or plastic putty, while larger cracks may need to be repaired with a soldering iron. With the right methods, repairing cracks in plastic is actually a lot easier than you might think.
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Method 1 of 4: Gluing Cracked Plastic
Step 1. Use plastic glue to repair small cracks in the plastic
If you want to reconnect cracked plastic, you can use a plastic glue specially formulated to glue the plastic layer together. Plastic glue is usually used to make models so that they are easy to use and safe for adults to use. Make sure you have enough glue to connect the cracked parts. You shouldn't stop halfway when you've applied strong glue!
You can also use super glue, but first check the packaging to make sure it works on plastic
Step 2. Apply glue to the edge of the cracked part
Gently squeeze the tube filled with glue, then apply the glue to the edges of the crack to be joined. Have a rag nearby in case you apply too much glue, then wipe off any excess glue with the cloth before it hardens. Glue dries quickly. So make sure you're really ready to join the crack before you start applying glue!
- Strong glue has a strong odor. Work in a well-ventilated area or wear a face shield when applying glue.
- Wear gloves when using a strong glue to prevent it from sticking to the skin making it difficult to clean.
Step 3. Connect the edges of the cracked part
When the glue has been applied to the edge of the cracked part, bring the two sides together so that they stick. Carefully align the edges. Press for 1 minute into the plastic you just joined to allow the glue to harden completely, then gently release it.
You can use C-shaped clamps (C-clamps) to hold the plastic together
Step 4. Let the glue dry completely
Once you have repaired the cracks in the plastic, it is very important to allow the glue to dry completely before applying the plastic. Different glues dry at different times. So, check the packaging to find out the specific drying time. Wait at least 1 hour before using the repaired plastic.
You can make the glue dry faster if you don't have time to wait for it to dry
Method 2 of 4: Using Hot Water
Step 1. Repair small cracks in the plastic with hot water
Plastics often do not need to be heated to extremes in order to soften and repair. Soaking the plastic in hot water can soften the texture of the plastic so that the cracked parts can be joined together. You can make the plastic harden quickly by soaking it in cold water.
Step 2. Prepare one container of hot water and one container of cold water
Fill a bowl or container with enough hot water to cover the cracked plastic part. After that, prepare a container of cold water and place it near you so that the plastic can be cooled immediately after repairing. Make sure you don't overfill the container to prevent water from spilling out while soaking the plastic.
Do not use boiling water when soaking plastic
Step 3. Place the cracked plastic in hot water
You may not need to soak the entire plastic part if you only want to fix small parts and not change the overall shape of the plastic. Some types of plastic may take longer to heat in the water. Soak cracked plastic in water for at least 30 seconds.
- Remove the plastic from the water periodically to check if the texture is soft enough to be reshaped.
- You can use tongs to hold the plastic in the hot water.
- Do not stir the plastic in the water. Just shut up.
Step 4. Remove the plastic from the water and connect the cracked part
When the plastic begins to soften and can be reshaped with your fingers, remove the plastic from the water. Put the cracked parts together. Do not squeeze the edges of the plastic to keep the shape flat.
Wear gloves or tongs to pull the plastic out of the hot water
Step 5. Soak the plastic in cold water until it hardens
After connecting the cracked parts, you should immediately cool the plastic to allow it to harden. Soak the plastic in a container of cold water. Do not stir the plastic in the water and let it sit for at least 30 seconds.
- You can use C-shaped tongs to hold the cracks together while submerging them in cold water. Just make sure you're not squeezing the plastic to keep it flat once it's hardened.
- Remove the plastic from the water and check to make sure it has hardened before using it again.
- Soak as much of the plastic as possible. Cooling the entire plastic piece will help it retain its shape.
Method 3 of 4: Making Plastic Putty with Solvents
Step 1. Use acetone to putty the plastic and cover the cracks
Acetone is a strong solvent that can melt all plastic parts. You can use acetone to make putty or melted plastic that will help repair cracks in the plastic. However, it is best not to use it to cover large holes or gaps as the result will look uneven.
Step 2. Fill a large glass container with acetone
Acetone can melt plastic. So, do not use containers such as cups or plastic buckets to contain them. Get a glass or ceramic bowl and fill it with enough acetone to cover some of the plastic pieces. You may find it difficult to clean all of the melted plastic once you're done. So, use used or unused bowls.
Acetone can give off toxic fumes. Make sure you are working in a well-ventilated area or wear face protection when working
Step 3. Soak some plastic pieces with acetone
You will melt the plastic to patch the crack. So, use plastic pieces that are no longer needed. The plastic can be in any shape because it will later be melted down for use. If you can, use used plastic that is similar to the cracked plastic that you want to repair.
- Do not let acetone on the skin because it can cause irritation.
- If you can't find a similar plastic, look for a plastic that is similar in color.
Step 4. Let the plastic pieces melt in the acetone overnight
The plastic will slowly disintegrate and turn into a thick slurry. Depending on the type of plastic being melted, the time it takes for the plastic to melt can vary widely. We recommend that you leave the plastic for more than 8 hours in acetone.
- You can speed up the melting time by cutting the plastic into small pieces.
- If there are still large clumps of plastic in the melt, you'll need more time to crush them.
Step 5. Pour in additional acetone
After the pieces of plastic are crushed with acetone, the plastic will decompose and sink to the bottom of the container. Gently remove the liquid in the container and leave the melted plastic at the bottom. Be careful and don't inhale the plastic smell.
- Acetone can melt plastic and damage grass. So, don't throw acetone in the trash or outside!
- The remaining acetone in the container will evaporate quickly.
Step 6. Apply plastic putty to the crack to fill it
Once the acetone has been completely removed from the mixture, you can apply plastic putty from the scrap plastic. Dip a small paint brush or cotton ball into the liquid plastic and use it to patch the crack. Make sure to fill it tightly and apply the putty until it's completely even.
Apply melted plastic to the underside of the crack to make it appear more subtle
Step 7. Let the plastic putty harden completely
The putty will begin to stick to the plastic and harden. It is very important to allow the putty to harden before starting to apply the plastic or the cracked parts will open again. Wait at least 1 hour before applying the freshly repaired plastic.
Method 4 of 4: Welding Plastic
Step 1. Use a soldering iron to repair large cracks in the plastic
A simple soldering iron can be a powerful way to repair cracks in plastic. The heat of the metal can melt the edges of the crack so that it can be reconnected easily without melting or changing the entire shape of the plastic. This tool is also easy to use and does not require additional materials.
Soldering irons can be purchased at hardware and home supply stores for around Rp. 100,000
Step 2. Let the soldering iron heat up
Plug in the power cord and turn on the soldering iron on the lowest heat setting. The iron takes a while to heat up, but you can use that time to prepare other materials. You should never use solder that has not reached the right temperature so that the plastic melts evenly.
- Do not place the soldering iron near flammable objects when heated.
- Make sure the tip of the soldering iron is clean of any residue.
- Plastic is much easier to melt than metal. So, your soldering iron doesn't need to be heated to over 200 C.
Step 3. Connect and seal the cracked parts
When the iron is heated, seal the edges of the cracked parts together, but don't overlap them. Try not to stretch or bend the rest of the plastic. If the edges of the cracked part are not connected, use a small piece of plastic as a patch by melting the edges and the edges of the cracked part, then glue them together.
- Use tongs to secure the cracked part so you can use both hands to solder it.
- If you are using a small piece of plastic as a patch, cut the plastic to the size of the crack and try to use plastic of the same type and color.
Step 4. Melt the edges of the crack with a soldering iron
Rub the hot tip of the soldering iron against the edges of the crack until it melts and sticks together. Make sure you heat the plastic surface evenly so that it blends smoothly. Let the plastic cool before putting it back on. There should be no excessive fire or smoke.
- The heating iron will feel very hot. So, be careful not to hurt yourself or anything else around you while doing it.
- Melting plastic can trigger toxic fumes. Work in a well-ventilated area or wear respiratory protection so you don't inhale the fumes.
Step 5. Allow the plastic to cool completely
The plastic must cool completely to harden again. If you use the plastic before the newly repaired part has hardened, make sure it can re-open making it difficult to repair. Re-melting plastic can change its original shape.
Wait at least 1 hour before using the newly repaired plastic
Step 6. Turn off and save the soldering iron
After you finish welding the plastic, turn it off and unplug the soldering iron, then let it cool down. Wipe the soldering tip clean to remove any plastic residue that has built up. After that, store the solder in a safe place.
- You may need to scrub the tip of the solder with a brush to get rid of the residue.
- You can use cleaning fluid to clean the soldering tip, but make sure the solder is removed first.
Warning
- Acetone is a toxic chemical. Don't inhale the smell, and make sure no liquid gets on the skin.
- Strong glue can produce toxic fumes. Work in a well-ventilated area or wear a face shield when working.
