How-to Guide – Hand Lay-up on Fiberglass Molds

img_0147

1. PREPARING THE MOLD

Remove dust and dirt from mold.

a. If mold is of plaster, wood, or new fiberglass, apply soft wax (Wax #2) and buff with soft towel. Then spray or brush with PVA parting compound and allow to dry.

b. If mold material is glass, metal, ceramic, or well-cured fiberglass, apply three coats of hard wax, carnauba type, buffing between each coat.

2. APPLYING THE GELCOAT

a. If gelcoat is to be brushed on, allow the first coat to cure and then apply second coat to make sure there are no light spots.

b. If gelcoat is to be sprayed on with a gelcoat gun, spray up to a thickness of .015” to .020”. When gelcoat has cured long enough that your fingernail cannot easily scrape it free (test at edge of mold where damage will not show on part) then proceed with next step.

3. LAY-UP SKIN COAT

Cut ¾ or 1 oz. mat to cover your part. Brush catalyzed resin over the cured gelcoat and then apply the mat. Work with the roller, adding more resin where necessary until all white areas in the mat fibers have disappeared and all air bubbles have escaped. A mohair roller is ideal for rolling in the resin, and a ribbed plastic or aluminum roller assists greatly in popping any remaining bubbles. Avoid leaving excess resin standing in puddles. Resin-rich areas weaken the part. Where rollers will not reach, brushes must be used. When this step is complete, clean all your tools in acetone. Allow skin coat to cure before next step.

  1. LAYING FIBERGLASS REINFORCEMENT

For a 12 ft. boat, two layers of 1½ oz. or 2 oz. mat and one layer of roving may be adequate, depending upon design. For a 14 ft. boat, an additional layer of mat and roving will add additional strength. Apply each layer as in step 3, but it will not be necessary to wait for curing between these layers. Be sure to shake all acetone out of brushes and rollers before applying resin. Acetone drips can result in uncured spots in the lay-up.

  1. TRIM

On a small lay-up, the fiberglass laminate which hangs over the edge of the mold can be trimmed off easily with a razor knife if you catch the “trim stage,” of the period after the lay-up has gelled but before it has hardened. On a larger lay-up, it can be trimmed with a saw or diamond blade.

  1. CURE

The cure may take from two hours to overnight, depending upon turnover desired, temperature, catalyzation, and nature of the part. If laid up in a female mold, longer cure will affect shrinkage and easier parting. In the case of the male mold, the part comes off more easily before it shrinks appreciably. If the part is subject to warping, a longer cure may be necessary. In any case, when the part is removed, it should be supported in its desired shape until fully cured.

  1. REMOVE PART FROM MOLD

First, examine the trim edge all the way around the mold and make sure there is no resin bridging the line between the mold and the part. Sand this edge where necessary. Then wooden or plastic wedges can be pushed into the edges to start the separation. Continue separation by pulling and flexing. In some cases, it is necessary to drill a small hole in the mold and apply air or water pressure.

  1. FINISH

Trim edges and back of part may need to be sanded and coated with surfacing resin or interior gelcoat.

  1. GELCOAT PROBLEMS

Alligatoring,” or wrinkling of the gelcoat may be due to the following reasons:

  1. Gelcoat is too thin in spots; consequently it does not completely cure.
  2. Insufficient hardener added, or hardener not mixed well enough. In general, it is best to use about twice as much hardener in gelcoat as in lay-up resin at the same room temperature, since the gelcoat goes on thinner than a mat lay-up.
  3. Gelcoat has not cured long enough before mat lay-up.
  4. Acetone from tools drips onto gelcoat or into skin lay-up.

8 Solvents for Cleaning Up your next Job

solventA major part of our business here at FGCI is dedicated to solvents. Solvents are used for many things, but especially for cleanup. When you finish a project, you want to be able to clean up your mess, right? Everything from cleaning spray guns and brushes to wiping down the project afterwards, solvents are an important part of your project process. When you start a project, you want to make sure you pick up something to clean up, but which one works best? Let’s look!

Acetone

Acetone is a necessity for cleaning up polyester resins and gelcoats. Acetone is also a very important step in treating your part before spraying gelcoat, as it helps get any and all oils off the part to avoid blemishes. This is probably the best overall cleaner.

Lacquer Thinner

Lacquer Thinner is a must for removing oils. You will see a lot of mechanics use this for parts cleaning and washing as it is great for removing a lot of the grease left by engines. You will also see this product offered in different degrees of purity, from the wash-grade to the medium to the high-grade.

Isopropyl Alcohol

Our Isopropyl Alcohol is 99% water free. This product is great for cleaning epoxy, especially for wiping down a new epoxy bar-top.

Mineral Spirits

Mineral Spirits are a tried and true paint cleaner you will see used by anyone painting a polyurethane or enamel paint as it breaks down the paint very quickly.

Styrene

Styrene is a common solution found in resins and gelcoats, sometimes called ‘wax.’ Styrene is commonly used to thin down resin to allow it to seep into wood easier. We don’t recommend using it to thin gelcoat, however.

Toluene

Toluene is a great multi-use product as it’s great for cleaning epoxy, but it also works for cleaning paint as well. Toluene is mainly used for cleaning up silicone and it does a great job on 5200.

T-12

T-12 is a very volatile solvent used mainly for cleaning epoxies. This solvent dries extremely quickly, but you will see it used frequently for cleaning brushes between uses.

Xylene

Xylene is used mainly as a thinner for enamels. It can also be used for cleanup for paints as well.

The most important thing to remember with all of these solvents is that they all require proper protection. Gloves and some sort of clothing protection would be the least you can do. You may also consider respirators and eye protection as well. You also want to remember that all of this material is flammable, so be cautious and store it properly.

Tech Blog – 5 tips on Thinning Gelcoat

maxresdefaultWhen 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.

  1. 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.
  2. 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.
  3. 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%.
  4. 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.
  5. 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).

Are you getting everything you need for your purchase?

One of the top problems we talk to customers about is making sure they get everything they need the first time for their project. It doesn’t sound as crucial for people who live mere minutes from one of our two locations, but it can be, and for people who are hours away, or even across the country, it becomes a necessity. With that in mind, let’s go over some items that are as neglected as batteries on Christmas morning.

Catalyst – Generally, MEK-P is the most neglected product. MEK-P catalyst is 124809essential for all resin and gelcoat; it’s what makes the product hard and it is a requirement that, unless you are ordering a kit, is not included. Make sure you go by the catalyst chart to find out how much you need. MEK-P comes in 1 oz, 2 oz, 8 oz, pint, quart and gallon jugs.

Brushable gel

 

Brushes or rollers – I can’t tell you how often people get home and get ready to mix their gelcoat or resin or epoxy and stop and wonder how they are going to apply it. For rollers, you want to make sure they are Phenolic roller covers or they will break up while rolling on the gelcoat and resin. With brushes, you can use our Chip brushes, or even our higher-end Glasskoter brushes.

Mixing buckets – Most problems from gelcoat or even epoxy come from either in-proper measuring or in-proper mixing. Many people (including me) go with the tried and true ‘eyeball method’ of measuring. The problem is epoxy and gelcoat are both very specific and very unforgiving on their measurements. If you aren’t exact, you can have a problem. Also remember; a $2 mixing bucket is way cheaper than throwing the product away and re-buying it because it didn’t harden properly. We sell mix and measure buckets perfect for mixing (and measuring) with measurement lines on the side in pint, quart, 2-1/2 quart and 5-quart sizes. For catalyst, we sell measuring cups, and my favorite, a squeeze bottle for quick, easy measuring.

Safety equipment – We’ve already talked a bit about safety equipment here, but it’s surprising how few people use gloves. Gloves are a vital part to a persons protection and it’s a cheap, easy purchase. A box of gloves is as inexpensive as $6.07 for a box of 100, so pick them up and they will last you a few projects.

solventSolvents for cleanup – Cleanup is one that almost always overlooked until the project is finished and the mess has been made. Gelcoat is not like paint, where you can use a damp rag; for gelcoat and resin, you will want to use Acetone for your cleanup needs. For epoxies, you will want to use T-12 and for paints, you will want to use mineral spirits to get the residue up. Just remember, with all solvents to be careful how and where you use them as they are harsh and can damage certain surfaces (like wood floors…don’t ask).

So, next time you need a project and you are at the showroom, or on our website, remember to get everything you need so your project can turn out amazing.

5 Tips on Various Fiberglass Coatings Solvents

1. Acetone is good for cleaning polyesters, but not epoxies.

129132

2. Lacquer Thinner tends to be a good solvent for cleaning surfaces to remove wax and oils.

129173

3. Isopropyl Alcohol 99% (water free) is a mild solvent that is recommended when using Epoxy Table Top Resin and cleaning new epoxy surfaces.

129155

4. Mineral Spirits works well with paint and polyurethane enamel.

129187

5. Styrene reduces polyester, iso and vinyl ester resins for better wood penetration.

129208