When a project calls for sanding, one must confirm the correct materials are being used. Reason being is due to the different sizing, backing and grit of the sandpaper. But, how can we identify what type of sandpaper is best? Subjected to the work needed for your project, grit size will come into play. Thus, we must make note that sandpaper is measured by its grit size while others are measured by both the grit and grade of the backing. When buying your sandpaper, check the item to confirm it states the pressure sensitive adhesive (PSA) or the grit and size number. This will help when deciding which one is best for the project at hand.
Sandpaper Grit Sizing: If you are looking to remove a previous material such as gelcoat; begin sanding your surface with a 150 grit or lower. A low grit number determines the coarseness of the sandpaper which will give you the ability to remove materials and coatings. Sandpaper with a grit number in the 200’s and higher would be great for finishes such as buffing, polishing or the removal of small scratches. A high grit number is equivalent to how small the grains are which will allow you to smooth the surface.
Sandpaper Weight Grade: One may see grade letters ranging from A-E which represents the durability of the sandpaper, where E is the strongest. For example, (based on the figure above) the red Mirka Royal 40 grit disc would be ranked as the most durable, next the Mirka Bulldog 120 grit Gold, followed by the gray Mirka Bulldog 400 grit Gold .
Here is a great tip!
If you are looking to conduct a wet or dry sanding, the sandpaper coating must be waterproof. An abrasive that is waterproof will last you longer with end results you’re aiming for in a wet/dry process.
When talking gelcoat, the most important aspect is the color. Everyone has their preference, and Fiberglass Coatings has a wide range of stock colors you can find on a daily basis. Did you know that we can match gelcoat for you, though? That’s right, we can take a sample you provide and make a gelcoat that will perfectly match your needs.
We have many customers who need to fix a blemish in the side of a boat, or even a pool. They need the gelcoat to match exactly. With gelcoat, it can fade in the sun and fun of Florida, so getting a factory color is not always an option. It may not match exactly and make a blemish stand out even worse. This is why we use a photospectrometer to match the gelcoat to a perfect match for you.
One of the more amazing products we carry is a brushable Gelcoat. This gelcoat is designed to be an easy way to re-apply gelcoat for fixing blemishes. When you order your colormatch, we can make a standard exterior gelcoat, or a brushable gelcoat. Be sure to check with your rep about what you need!
There are a few different ways to get us the color you need. The easiest way is to send us a sample, like a hatch or chip of gelcoat to match. You can mail it to
4301 34th St. N.
St. Petersburg, FL 33714
You can also bring the sample in to one of our two showrooms in Florida. Now, if you don’t have the ability to send us a sample, I generally recommend going to a store that has color samples and picking out the closest one to send to us and have us match that.
If you just can’t find what you want, we also sell the neutral gelcoat and pigment jars to tint your own gelcoat! Let us know how we can help!
If you haven’t read our end-all guide on how to apply the gelcoat, be sure to check it out HERE.
Brushable Gelcoat is a specially formulated product that is made to be applied like paint and eliminate the need for spray equipment. It has excellent leveling, Water/Osmosis resistance, UV light Stability, great Gloss Retention and a fantastic long-term durability. It comes in many different colors and can be bought online or in our stores! So, let’s talk about some tips on how to get the most out of the Brushable Gelcoat.
Don’t add Patch Booster or Sanding Aid! You heard that right, you don’t need to add sanding aid to Brushable gelcoat to have it dry tack free! The self-leveling technology added doesn’t require any additional products or additives.
Proper gelcoat application requires you apply your coats about 15-20 mils thick,
using a mil gauge.
Allow the gelcoat to cure overnight and then lightly sand it and buff it for an outstanding shine!
Use Acetone for your cleanup. Just like other Polyester-based products, Acetone is the best cleanup material!
The most important step: Adding the proper amount of Catalyst. We recommend 1.5%-2% Catalyst ratio. After adding the catalyst, you will want to mix for two minutes, preferably with a mechanical agitator (drill mixer). For your reference, here is the catalyst chart so you know exactly how much catalyst you need.
BONUS TIP: In the hot Florida weather, working time is tough for any gelcoat. So our FGCI Pro Tip is to chill the gelcoat down to 70 degrees before mixing. This way you can get a bit longer working time.
DID YOU KNOW: That FGCI Colormatches gelcoat? We can make as little as a gallon to nearly any sample you have. Call us for details!
When it comes to applying gelcoat, you really only have two kinds of methods; you can brush our brushable gelcoat, or you can use our standard gelcoat and spray it. Most go with spraying the gelcoat to give you the best finish. When spraying gelcoat, you will need a spray gun with a 3.0 tip or larger. If you don’t have a tip that large, most people generally thin the gelcoat. Everyone asks what you use to thin gelcoat, and everyone has an answer. Let me start by saying we don’t recommend thinning gelcoat if you can avoid it. Our techs liken it to chicken soup; the more water you add to it, the less like chicken soup it will be.
Do NOT use Acetone. I have heard people recommend this, but it can cause all kinds of problems for gelcoat from running to fish-eyes to a yellowing of the colors.
We recommend Patch Booster. Patch booster is an additive that will thin out your gelcoat while preventing running. The product will not affect colors like styrene or acetone and is added up to 25 percent by volume to your gelcoat (one quart per gallon). You will want to catalyze the gelcoat at 2% when you add this additive.
We also recommend Duratec High-Gloss additive. This product has the added benefit of giving you a glossy shine without having to sand and buff at the end. The product also thins the gelcoat and will not affect the colors like styrene and acetone will. It can be used up to 50 percent by volume. If there is one tip we could offer, it would be to wait 24 hours before buffing when using this product. Buffing will give you a new-car shine. You will want to make sure you catalyze this product at 2%.
We do not recommend Styrene for one main reason; it can affect colors. Styrene, when added up to 20% will thin your gelcoat but does often cause the gelcoat to yellow and any more than 20 percent will cause fish-eye.
Both the Patch Booster and the Duratec affect your catalyst rate, so make sure you catalize properly before spraying and be sure to clean your gun carefully after each use (for that, you CAN use Acetone).