Fiberglass Repair: How to Do it Yourself
Fiberglass is an amazingly strong and durable material that is great for many types of repairs. This type of repair is usually done by a fiberglass professional.
Start by removing any contamination and cleaning the surface. Dampen a clean rag with acetone and wipe the damaged area.
Scarfing means sanding the old fiberglass at a ratio of 12:1 (for every 1 unit of thickness, you must sand it away by 12 units). This will allow the new patch to match the stiffness of the original fiberglass.
The fiberglass repair process can seem intimidating to a beginner. But with the right tools, it’s possible to perform structural and cosmetic repairs on your own. It all starts with a thorough inspection of the damage to determine if it impacts the integrity of the structure. Once you’ve determined this, you can move on to the repairs.
Scratches are easily repaired by sanding away the damaged gelcoat and then polishing it to restore the luster of your fiberglass. You can purchase a gelcoat repair kit that includes sanding compound, a polishing pad, mixing sticks, and sealing film for under $20.
You’ll also want to be sure you have a quality, flexible plastic spreader for the sanding compound. You’ll also need sheets of 150-, 220-, 400-, and 600-grit wet-or-dry sandpaper. Before sanding, clean the surface to be repaired using a clean rag wet with acetone. This removes any residual mold release, wax surfactant, and other contaminants from the fiberglass surface. Grinding the damaged area without dewaxing first can weaken the adhesion of your repair and create micro-cracks around the edges of the scratch.
Once you’ve sanded the area to be repaired, mask off any adjacent areas or items with two-inch-wide 3M ScotchBlue Multi-Surface Painter’s Tape No. 2090. This protects them from inadvertently applied gelcoat or errant sanding. It’s important to allow a 16th of an inch of unmasked margin around the damaged area.
Next, mix a small batch of TotalBoat 5:1 epoxy resin and slow hardener to ketchup consistency. Brush on a thin coat of this mixture to repair the damaged fiberglass. Allow it to dry before applying any additional layers of epoxy and fiberglass cloth.
When finished, your fiberglass repair will look like it never even happened. A few scratches from a muffed landing, a dropped pair of pliers, or some other minor mishap are easy to fix with a little patience and the right materials. Performing these simple repairs can save you thousands of dollars when compared to replacement costs and will give you confidence that your fiberglass structures are strong, durable, and protected.
Repairing a dent
The slick fiberglass surface of a boat’s hull is prone to chips and dents that mar its appearance. While these dings might not seem like a big deal at first, they can become structural problems in the future if left untreated. Fiberglass is a strong and durable material that can easily handle the occasional bump and scrape, but it requires care when working with it to prevent cracks and other problems.
Before attempting to repair a dent, the area needs to be clean and dry. Use acetone to wipe away any residue or moisture on the damaged area. Then, mark the affected area with a contrasting marker. This will help you locate the ding when applying the fiberglass patch. Next, remove the damaged portion of the object, taking care to leave enough material around it to support the new laminate.
Whether you’re repairing a fiberglass car door or a boat ding, the process will be similar. First, you’ll need to prepare the area for bonding. Mask off undamaged areas that are close to the area you’re repairing. Then, use a rotary tool with a pointed grinding bit to dig out the gelcoat in the affected area, taking care not to gouge the fiberglass beneath.
Once the area is cleaned and sanded down, it’s time to prepare the bonding materials. To ensure maximum adhesion, you’ll need to increase the surface area that will be bonded with the epoxy resin. To do this, you can either use a taper or scarf sanding technique. To do this, you’ll need to cut pieces of fiberglass cloth that are longer than the affected area. Then, you’ll need to cut a piece of fiberglass mat that is a little wider than the damaged area.
You’ll also need to mix the resin ingredients according to the manufacturer’s instructions. Most fiberglass repair kits come with a combination of polyester and vinylester resin, along with methyl ethyl ketone peroxide (MEKP) as the catalyst. This will need to be mixed thoroughly, as air bubbles can lead to structural defects in the finished product.
Repairing a crack
If you have a cosmetic crack in your fiberglass boat, it’s a good idea to repair it before the damage gets worse. Fiberglass is extremely durable, and a small crack can develop into one that’s significantly larger. A little bit of care and some fiberglass patching can save you a lot of time, money, and hassle.
First, make sure you are working in a safe and well-ventilated area. You will also need to evaluate the extent of the damage. If the crack has gone all the way through the structural decking, you will likely need to do a more in-depth repair that includes the replacement of damaged components. If the crack is only in the gel coat, you can probably get away with a simple cosmetic repair.
You will need a couple of common tools for the job, such as a drill and an electric grinder with a wheel attachment. You should also use protective equipment like gloves, a respirator, and goggles. After you have gathered your materials and tools, start by cleaning the affected area. This is done to remove dirt, grease, and other impurities from the surface that you are repairing.
Next, mix the resin and hardener in the proportions recommended on the packaging. Brush a coat of the mixture onto the damaged area, making sure it extends 2-3 inches past the edge of the crack. Once the area is wet, place a piece of fiberglass mat or cloth on top of it. Press down to saturate the fiberglass with the resin and to remove air bubbles.
Repeat the previous steps with additional layers of mat and cloth until you have built up a layer that is equal to the original thickness of the fiberglass. Allow each layer to cure for a few hours before you move on to the next step.
When you have finished the repair, sand the area with a disk sander to create a smooth surface. This will help the repaired area blend in with the rest of your boat’s structure. If you have used epoxy fiberglass resin, you can recoat the entire surface with fresh resin after the sanding.
Repairing a hole
If your boat gets hit by a wave and you end up with a large hole in your fiberglass hull, it may seem impossible to repair the damage. But it is actually very easy if you know the proper procedure. To start, you will want to clean the area around the hole with an automotive prep solvent (such as acetone). Wipe down the surface until it is completely clean and free of contamination.
Next, you will want to prepare the epoxy resin ingredients. You will need to mix a ratio of 5 parts resin to 1 part slow hardener in a clean plastic mixing cup. Then, add a little bit of TotalBoat Silica Thickener to the mixture to achieve a “ketchup” consistency. This will make it easier to brush the mixed resin onto the surface of the hull.
Once the mixed resin is ready, you will want to pre-cut some fiberglass mat or cloth to fit the area to be repaired. This piece of mat or cloth will need to extend 2-3 inches past the edge of the damaged area. This will be the backer layer that will help the patch bond to the existing fiberglass structure underneath it.
After the mat or cloth has been cut, it will need to be soaked in resin. You will want to saturate the material with enough resin to fill up any low spots on the surface of the damaged hull. Once the mat is soaked in resin, you will need to let it dry for about 10 minutes.
Finally, you will need to sand the patch. You can use a random orbital sander or a disk sander, depending on the severity of the damage. Be sure to sand until the patch is in line with the surrounding finished surface of the fiberglass.
The last step is to apply a gelcoat to the sanded patch. This will seal the patch and give it a beautiful shine. Then, you will be able to enjoy your newly-repaired fiberglass hull without worrying about the pesky holes or cracks that can easily form in any fiberglass surface.