When a plastic item breaks, you may think it's easier to get rid of it than to try to fix it, but working with this type of material is easier than you might think. The secret to obtaining a good result is to melt the contact parts between the object and the piece to be reattached, so that they can form a homogeneous and solid surface again. If you can't do this using a specific glue for plastic, you can try to melt the damaged edges with a soldering iron. Even a strong chemical solvent (such as acetone) can completely dissolve some types of plastics; the resulting sticky fluid, if necessary, can be applied with a brush on the object to be repaired.
Steps
Method 1 of 3: Repair Small Pieces with Glue
Step 1. Get a tube of high strength glue specifically for plastics
If you need to repair a chipped edge or reattach the fragment of an object, a tough adhesive will suffice. This specific type of glue is formulated to create bonds between surfaces at the molecular level. Look for a product that is suitable for the type of plastic you are trying to fix.
- Many standard-purpose superglues can perform equally well on plastics.
- You can find a variety of plastic glues, superglues and other similar DIY adhesives at hardware or home improvement stores.
- Purchase enough glue to get the whole job done.
Step 2. Spread the glue over the edges of the broken piece
To ensure a secure grip, apply the adhesive to all points that will come into contact with the damaged object. Hold the tube with your dominant hand and press it lightly to release a minimum amount of glue, so there will be no risk of putting in too much and you will avoid dirtying the work surface.
Wear a pair of rubber gloves when using the glue to prevent some of it from sticking to your skin
Step 3. Place the plastic piece in place by pressing lightly
Align the edges carefully: the plastic glue has a very quick setting and once it has set you will not be able to fix the piece. Apply gentle pressure for about 30-60 seconds, thus preventing the two pieces from moving before the glue hardens.
- You can help by placing duct tape to hold the two parts together, or by placing a weight on top of the object to keep it stationary.
- For oddly shaped objects a C-clamp might be useful.
Step 4. Let the glue harden
Each glue has its own drying time, but as a general rule it will take 1-2 hours to be able to handle the object without risking to make the pieces come off again.
- Some types of glue can take up to 24 hours to fully harden.
- Consult the instructions specified in the product packaging to make sure you follow all recommendations for use.
Method 2 of 3: Melting the Plastic with a Soldering Iron
Step 1. Glue the piece in place
Begin to rejoin the separate pieces by securing them with a strong plastic adhesive. You must have both hands free to work safely with the tools you are about to use.
- Apply just enough glue to hold the parts together. Many adhesives react to the heat from the soldering iron causing discoloration.
- When you need to repair a crack, crack, or clean break, the only way to get a result is to melt the plastic.
Step 2. Heat up the soldering iron
Turn on the soldering iron and set it to the lowest temperature. While you wait for it to get to the required level of heat, prepare everything you need to do the job you are about to do. The soldering iron can take several minutes to warm up.
- Do not set your soldering iron to a temperature above 200 ° C. Plastic to melt requires lower temperatures than metals.
- Before starting, clean the tip of the soldering iron with a damp sponge to remove any residue from previous work.
Step 3. With the soldering iron melt the edges of the plastic
With the tip of the soldering iron try to smooth the joint between the two surfaces as much as possible. The intense heat will instantly liquefy the plastic making it soft on both sides, thus allowing a perfect weld. When the plastic cools, it will become hard and tough again. The repair will therefore be much longer lasting than simply gluing.
- When possible, weld in the back so that it is less visible.
- When using a soldering iron, always wear protective goggles for your own safety. It is also advisable to use a respirator or a safety mask and work in a well ventilated area, to avoid inhaling the harmful smoke of the plastic.
Step 4. Patch the large holes with other plastic scraps
If an entire section is missing from the object you are trying to repair, you may want to fix it by using a replacement piece of plastic, similar in color, texture, and thickness. Solder the patch as you would a normal break, running the soldering iron tip along the edges of the new piece until it blends into the larger surface.
The ideal is to use a piece of plastic of the same type as the object to be repaired, however in many cases the job will be successful even if the plastic is not exactly identical
Step 5. Smooth the resulting weld to even it out
Go over the edges of the seam of coarse sandpaper (about 120) until the most noticeable roughness has disappeared. Then with a damp cloth, clean the object to eliminate traces of dust caused by sanding.
For an even smoother finish, you can use coarser grit sandpaper to remove the most noticeable imperfections (such as bumps and roughness), then finish the job with a finer grit paper (300 grit or higher) to even out the surface
Method 3 of 3: Solder the Plastic with Acetone
Step 1. Pour the acetone into a glass container
Take a glass, jar or cup that is deep enough and with a wide opening and pour 7-10 cm of pure acetone into it. The container should be full enough to cover several pieces of plastic. When you're done, there may be some hard-to-remove residue left in the container, so use one you don't care much for.
- It is important that the container used is glass or ceramic otherwise, in addition to the plastic you are using, you will also melt the container.
- Acetone is a dangerous liquid because it gives off potentially harmful fumes, so work in a well-ventilated environment.
Step 2. Put a few pieces of waste plastic into the acetone
Help yourself with a toothpick to make them soak well, all the way to the bottom of the container. If necessary, add a splash of acetone again to cover the tops of the irregularly sized pieces.
- To get a less noticeable weld, try to find plastic that is the same color as the object you need to repair.
- Don't touch the acetone. Contact with the skin may cause slight irritation.
Step 3. Leave the plastic in the solvent overnight
By soaking in acetone it will dissolve in a thick and sticky slurry. The time it takes will depend on the type of plastic you are using and its quantity. To be safe, leave it soaking for 8-12 hours.
- To speed up the process, cut or break the plastic into smaller pieces. The acetone will act faster if it has more access points.
- The slurry should have a smooth, creamy consistency, free from lumps or undissolved parts, to allow for the welding of other pieces.
Step 4. When the plastic has melted, being heavier it will separate from the acetone, settling on the bottom of the container
Don't throw the residual solvent down a sink or toilet - you'll need to dispose of it as chemical waste. Pour it into an airtight container and take it to a special waste disposal site. Strain the liquid into a glass jar, so that only the plastic slurry remains that you will use as a sealant for your repairs.
It doesn't matter if acetone residues remain in the container: they will evaporate soon
Step 5. Using a brush, apply the resulting substance to the damaged surface
Dip a thin brush or cotton swab into the liquefied plastic and dab the gap between the two broken pieces. Try to go as deep as possible. Keep working with the brush until you have filled in gaps and cracks well.
- If possible, try to apply the material to the most hidden part of the object you are repairing so that the repair does not show up.
- Use all the plastic you need to get a perfect seal on the damaged item (you will probably have leftovers).
Step 6. Give the plastic time to harden
Within a few minutes the last traces of acetone will evaporate and the fluid will form a chemical bond with the surrounding surface; in the meantime avoid touching the welded pieces. As soon as the new plastic has solidified, the item will be almost as good as new.
The new seal will have 95% strength compared to the original plastic
Advice
- Before investing time and effort in a complicated weld, consider whether it is worth it. If the plastic object is modest it can be easily replaced without the hassle of gluing and welding.
- As much as possible, use glues and patches of the same type as the plastic you need to repair.
- For more complicated projects you can use plastic ties as a resource material. They can be found in various colors, so it will not be difficult to find the perfect combination.
Warnings
- Always follow all safety precautions when using a soldering iron. If you are not familiar with the tool, ask for help from someone more experienced.
- Do not smoke and do not use open flames when using acetone. Both the liquid and its vapors are extremely flammable.
