• Spraying Gelcoat Over Old Gelcoats

Let me introduce our Spider-Crack Repair Kit, including everything you need to fix those pesky cracks: 1 – Cordless two-speed dremel tool, complete with bits to bore out the cracks; 1 – ½ pint of Gelcoat Putty to fill in the bored out cracks; 1 – 1 oz MEKP bottle to catalyze the putty (see catalyst chart for amounts).

Spider Cracks are a thorn in many boaters side. They seem to appear out of nowhere, and for no reason. Fixing them can involve more than just slapping on some gelcoat, however, and that is where we come in!

The first step needs to be ensuring that your spider cracks are just that, and not a sign of a soggy core, or a broken support. If the underside looks solid, and the surface is steady, then a spider crack is just a spider crack.

For properly fixing a spider crack, you will want to open the cracks to properly fill them. Usually, the easiest way to do that is with a Dremel. Once you open the cracks to a good size, you can lightly sand the surface and wash it down with soap and water, or Acetone to get the surface clean.

From there, you will want some Gelcoat Putty. Gelcoat putty is sold in many sizes, and only requires you mix in a 1-1/2% ratio of MEK-P Catalyst. Once mixed properly, you can use a putty knife to work the putty in the cracks. Once dry, you will sand to a nice, smooth surface and you are ready for the last part.

Now that you have a nice, smooth surface, you probably notice your white patch is still, well, white. Now you want to apply some gelcoat over the top to cover your patch. We can match gelcoat to a sample you provide, or you can check out the stock colors we have. We even have a brushable gelcoat that just requires you to brush it on and be done.

So, there you have it! Your patch is done, and that pesky spider crack is gone, and your boat is good as new! If you have any questions, you can call our technicians or comment in the section below. We are here to help!

Spider cracks are a form of fiberglass damage that occurs from minor flexing or impacts. They can occur in any form of fiberglass, including cars, boats and swimming pools. Small cracks form in the outer surface of the fiberglass, spreading out from a central point like a spiderweb. These cracks do not affect the structural integrity of the fiberglass, but are an aesthetic issue. Fortunately, spider cracks are not difficult to repair.

Step 1

Clean the area with acetone and a rag to remove any dirt or other impurities.

Step 2

Sand the damaged area with 100-grit sandpaper to roughen the surface. You can sand by hand or with an electric sander.

Step 3

Wash the area with acetone a second time to remove all sanding dust.

Step 4

Mask off the area around the cracks with masking tape and plaster to protect against drips.

Spraying Gelcoat Over Old Gelcoats

Step 5

Pull all of the loose bristles out of a cheap paint brush. Loose bristles may become embedded in the gelcoat.

Step 6

Measure a small amount of gelcoat, which is a thick form of fiberglass resin, into a paper bucket. If the fiberglass will be exposed to water, the gelcoat should be marine grade.

Step 7

Mix catalyst into the gelcoat following the instructions on the container. Precision is important: if you add too much catalyst the gelcoat will cure faster than it can be used, but if you add too little it won't cure at all.

Step 8

Brush a thin layer of gelcoat onto the sanded area, feathering it out a bit onto the surrounding fiberglass surface.

Step 9

Allow the gelcoat to sit for three hours, then spray it lightly with Polyvinal Alcohol to help it fully cure.

Step 12

Sand the area with 300-grit sandpaper to begin smoothing it. Re-sand it with 600-grit, then 900-grit and so on. Keep jumping 300 grit at a time until the repeated sanding has produced as smooth of a finish as you require.

Prime and paint the fiberglass to match the surrounding surface if needed.

Warnings

• Wear rubber gloves when working with gelcoat.
• Work in a well-ventilated area.

Items you will need

• Acetone
• Rag
• Sandpaper
• Electric sander (optional)
• Masking tape
• Plastic sheeting
• Paintbrush
• Gelcoat
• Paper bucket
• Catalyst
• Mixing stick
• Polyvinyl Alcohol
• Spray gun
• Soapy water and sponge
• Primer and paint (optional)

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