How to get fiberglass out of hand – How to Get Fiberglass Insulation Out of the Eyes

How to Get Fiberglass Insulation Out of the Eyes

Fiberglass is a man-made insulation fiber that features glass as its main fiber-forming substance. While it’s not difficult to install fiberglass insulation on your own, there are risks involved. Since fiberglass insulation fibers are quite small, they can easily get onto the skin, into the eyes or be inhaled. Fibers lodged in eyeballs, under eyelids and in the eye corners can cause painful irritation, scratch the eyeball and even cause permanent damage. Cleansing the eyes is necessary to get the fibers out; to do this well, most people will require an assistant.

  1. Remove yourself from the environment containing the fiberglass insulation. Move to an area where there are no insulation fibers in the air or on surfaces.

  2. Ensure everyone involved in the eye-cleansing process washes their hands with soap thoroughly, removing any dirt, fiberglass or other harmful matter.

  3. Examine the affected eye closely to determine the number of fiberglass insulation fibers you’re dealing with. If there seem to be a small amount, proceed to step four. If you notice a large number of fibers embedded in and around the eye, seek help from a medical professional instead of attempting to remove the fibers on your own.

  4. Place one finger on the skin of the eyelid, behind the eyelashes. Pull the eyelid up with the finger until there is space in and around the eye for a stream of water.

  5. Apply a gentle and steady stream of pure water or eyewash to the underside of the eyelid. Repeat this procedure under the eye and around to the sides of the eye, being very thorough.

  6. Re-examine the eye with the eyelid still pulled back. If fibers remain, repeat step five. Continue to alternate examining and flushing the eye until all the fibers are rinsed out. As long as the cornea isn’t scratched, there should be no permanent eye damage.

  7. Visit a medical professional if you aren’t able to flush out all the insulation fibers or if eye irritation persists.

  8. Tip

    Wear safety goggles with side shields to minimize the chance of getting insulation fibers in the eyes.

    Make sure there are eyewash and safety shower stations nearby when you’re working with fiberglass insulation.


    Don’t ever try to pluck the fibers out with your fingers or a tool, such as tweezers, brushes or blades; this can cause damage to the eye. Don’t rub or scratch your eyes while insulation fibers are in them; the fibers could scratch the cornea and cause damage.

Tips for Getting Rid of Fiberglass in Your Clothing — How to Wash Fiberglass Out of Clothing

After finishing a project or work day where exposed to fiberglass, remove your clothes in an area where the particles won’t shake off onto other fabrics. It’s probably not the best time to give your spouse or partner a tight bear hug either. Remove clothing and keep it separate from other laundry or furnishing — for example, don’t drape it on a chair or across the bed or the fibers may spread. It may work best to just toss the clothing into an empty washing machine and plan on washing it by itself rather than mixing the pieces with others.

Many companies that work with fiberglass products publish statements in their required Material Handling Data Sheets (MSDS) suggesting that clothing be washed separately and in warm water until fibers are removed. However, no specific guidelines for soaps or detergents and methods are given. Forums suggest using boar’s hair or other rough-bristled brushes to slough off some of the fibers before washing. Others mention applying strips of tape or other adhesives to pull the particles out before putting the clothes in the machine. Most sources do add a step after washing that includes thoroughly washing and rinsing the washing machine itself after finishing a load of clothing.

How clean and fiberglass-free you can get your clothes also depends on how much you were immersed in disrupted fiberglass. Many projects involve working with the composite form, which is tight and has little fiber shedding, so a normal wash cycle, or two or more, may be enough to ready your clothes for the next project.

Related Articles


  • American Lung Association. «Fiberglass.» 2012. (Apr. 7, 2012)
  • City of New York. «Fiberglass.» 2012. (Apr. 6, 2012)
  • Encyclopaedia Britannica. «Fiberglass.» 2012. (Apr. 6, 2012)
  • Owens Corning. «Material Safety Data Sheet.» July 17, 2007. (Apr. 7, 2012)
  • Illinois Department of Public Health «Environmental Health Fact Sheet: Fiberglass.» State.IL.US. 2012. (Apr. 6, 2012)

Fiberglass Preparation — Paint How To

The Starting Point For Awesome Paint

So you did your homework, shopped around, and decided on a fiberglass body for your next project. Cool. But you don’t want your car to wind up looking like a dune buggy or a boat hull, right? You want the smooth, sleek look of steel.

No problem. The trick to great paint on fiberglass (well, on any surface actually) is proper prep. You know—applying just the right amount of filler, blocking a guidecoat to check for low spots, that sort of thing. In a lot of ways, prepping ’glass is just like prepping metal. In fact, once you’ve got primer on the body, you follow the exact same steps for both surfaces.

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With fiberglass, however, the procedures before priming are quite different, because the material is so very different. Understanding what fiberglass is and coping with its quirks are the first steps toward giving fiberglass a finish that looks like sheetmetal.

Proper fiberglass prep starts well before you get out the sandpaper. It really begins when choosing the body itself. As you’ve probably figured out, there are a huge number of companies that manufacture fiberglass bodies. Unfortunately, there are probably as many levels of body quality as there are body suppliers. Here are a couple key qualities to help you sort them out.

Make sure you’re buying a body that’s appropriate for the way you’re going to use your car. If you’re building a street car, don’t buy a race car body, and vice versa. Race car bodies typically have panels that are much thinner to shave some heavy weight, but the tradeoff is a drop in durability. Stone chips, for example, will wreak havoc on a race car body.

Look for a body that’s made of hand-laid fiberglass. That means fiberglass mats were laid on top of the gelcoat in the molds, which ensures uniform panel thickness no matter which way the panels bend or crease. If the fiberglass was shot onto the gelcoat using a chopper gun, there’s no guarantee of uniformity, especially in the curves and corners. (Chopper guns are best used for broad, flat surfaces, like boat hulls.) It’s also harder to maintain a uniform amount of resin when using a chopper gun, and too much resin in the fiberglass makes the panels brittle.

Speaking of resin, check with your body manufacturer to see if it uses tooling resin or general-purpose resin in the molds. Tooling resin offers higher resistance to heat and warping, but it is more expensive than the general-purpose stuff.

Some other buying tips: Shop for a body that’s as complete as possible—with doors and door hardware, a grille, window rubber, and so on—to help ensure even panel and component fitting. Some companies send their bodies out “hung and latched,” so you don’t have to worry about properly fitting the doors, hood, and trunk lid. Others sell rolling chassis that are designed for a precise fit under their bodies. Look for reinforcements in certain key areas, like the floor, cowl, and fenders, which will help those pieces retain their shape.

Once you have your body, assemble it in the raw gelcoat and let it sit out in the sun and cure. The sun’s heat will work out air bubbles in the resin so they won’t cause problems when you paint. The heat will also tighten up the ’glass, which can affect panel fit, so you don’t want to do any trimming or shimming of panels when you assemble the body at this stage. This tightening of the fiberglass also gives the panels a “memory” of how they fit together, so they’ll go back together more easily after you’ve taken them apart to paint them.

How long should you cure the body? “The longer the better,” was the consensus among the experts we spoke with. The minimum time mentioned was 48 hours, while others said it should cure for weeks, maybe even months, especially if the car will be finished in black or another dark color. Since dark colors absorb heat, you don’t want the heat to bring more bubbles out of the resin, or cause the panels to warp or shrink, after the paint is on.

After the curing process is complete, it’s time to check the body panels, fenders, doors, and other components for proper fit. As Dennis Taylor (of Dennis Taylor’s Reproductions) told us, “Fiberglass bodies were never assembled in Detroit, so you can’t just assume the panels will fit.” Coming from a body manufacturer, that’s remarkably candid. Some manufacturers claim that their bodies will almost fall together and require barely a scuffing before paint.

The painters, however, tell a different story. “They all need some help,” said SoCal Speed Shop’s Mick Jenkins. And if you didn’t assemble the whole body before curing, do so before sanding and priming. “Don’t just hang the doors and assume everything else will fit,” Jenkins said. “Some parts may fit better than others.”

Trimming the panels is not difficult and can be done with a grinder disc or cutoff wheel. Be sure to protect yourself, as fiberglass dust is nasty stuff. Wear eye protection, a mask so you don’t inhale the ’glass dust, and cover your skin with long pants, sleeves, and gloves, or you’ll be itching for days to come.

If you have to use shims to properly gap an area—to fit the doors, for example—keep in mind that because of fiberglass’s flexibility, shimming in one place may throw off the gap somewhere else. There’s action and reaction, so be careful.

There are a couple of ways to fix a part that’s too small. You don’t necessarily need to get out the glass cloth and resin; Marson’s Marglass or Evercoat Kitty Hair will fill in a small area. However, if the fit is way off, you may need to cut the panel in half and add a fiberglass section to the middle. This can get complicated. Not only do you need to pay attention to exactly how much material you’re adding—so the part doesn’t get too big—but you also have to make sure the entire panel retains its shape. You may need to build a buck to maintain the curve of a door, for example.

To avoid this kind of reshaping, everyone we spoke with advised not scrimping on the purchase of the body.

We heard, “You get what you pay for,” over and over again. Spending a few extra bucks up front should keep you from having to do major fiberglass work to get the parts to fit.

Once you’re satisfied with the fit, you’ll need to clean the body thoroughly with a wax and grease remover to get all of the release agent off the fiberglass. If the body is not clean, those agents will create fisheyes in the paint.

Now it’s time to start sanding. Before you begin, be sure the body panels are well supported, otherwise you risk changing their shape by pushing on them with the sanding block.

One of the nice things about fiberglass bodies is that their gelcoat finish acts like an initial guidecoat. Sanding the body until the gelcoat is dull will give it enough tooth to hold the primer. It will also show off any low spots in the panels, as they will remain glossy when the surface around them is dull. Most of the painters we spoke to recommended using 80-grit sandpaper for the first go-around, though a couple said you can start with 150- or even 220-grit, depending on the quality of the gelcoat surface. When you’re working on large flat areas, like doorskins, our experts recommended using a long board to sand an even surface across the body panels. If the car’s body has too many curves to use a long board, a rubber sanding block will help conform the sandpaper to the panel shapes.

Two warnings about sanding gelcoat: Use caution so you don’t sand through the gelcoat layer, as that might open pinholes in the fiberglass that will later erupt, volcano-like, through the paint. Also, do not wet-sand the bare gelcoat. It’s porous and may trap water that will later blister the paint.

There are a couple of ways to treat low spots in the fiberglass. One is to use standard body filler or glazing putty. We also heard that a filling primer can do the trick. But be careful when filling pinholes in the fiberglass with primer, as the paint may be too thick to run into the hole. Instead, force some filler or putty into the hole with your finger, then knock off the excess with a second sanding pass. If you made the first pass with 80-grit, go to a 180- or 220-grit to smooth the filler and any scratches created by the 80-grit. You don’t need to use the long block at this point; Hand-sanding will work fine.

When we asked about shooting primer, each painter had his own favorite type of paint and method of painting. Most took the body apart and painted the parts separately. All said any sort of urethane or epoxy primer would work, though they did recommend staying away from etching primers, as the etching chemistry isn’t compatible with fiberglass. Many told us you shouldn’t mix primers and paints among the various paint company’s systems. Start and finish with one system, like PPG’s Global System, for best results. Once the first primer coat is on the body, the remaining paint steps are identical to what you’d do with sheetmetal.

Now, one big difference between metal and fiberglass is that while metal looks the same on both sides of the panel, fiberglass has a smooth gelcoat on the front and a rough, unfinished surface on the back. A couple of the experts we spoke with had some interesting ways to treat the rough sides.

Pete Santini and Kustom City’s Scott Holton used Line-X, a brand of spray-on bedliner, to finish the undersides of fenders. The protective layer adds durability to the fiberglass, and the black rubbery material looks just fine in the fender wells. Holton is using the Line-X material on the inside of a Willys coupe body as well, as it covers the raw fiberglass and cuts down on the fiberglass’ pungent aroma.

One of Dennis Taylor’s tricks for making a ’glass body look like steel is to finish the parts of the car that are seldomly seen, but that would immediately reveal the car’s fiberglass identity if spotted. His main targets are the rough areas on the backside of the hood and trunk lid. They don’t require the same kind of finesse that the body panels do, but some attention makes a world of difference. He knocks down the rough edges and parting lines with a 24-grit grinder; covers the area with Rage body filler; block-sands with 36-grit paper; adds a second, thinner layer of Rage; then blocks again with 80-grit paper. He says this is a better way to finish these areas than to just pour in resin or gelcoat, as these materials by themselves can get brittle.

There you have it. Prepping fiberglass isn’t much trickier than prepping metal. Just take care to cure, fit, and sand the raw panels properly, and you’ll have a finish you can be proud of.

How Do You Wash Fiberglass Out of Clothing?


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How To Make Your Fiberglass Gleam

To Magazine Home Page

By Lenny Rudow

Seal out the oncoming winter with rubbing, buffing, waxing, and polishing, but don’t forget the elbow grease.

Hold the buffer flat against the hull sides, and apply pressure evenly.


For more , check out the BoatTECH section of our website.

Keeping gelcoat properly maintained isn’t just a matter of vanity, it’s also a matter of protecting your boat’s fiberglass. Now that we have that out of the way, let’s get real — you do want to dazzle your slip neighbors with the mirror-like hull sides on Mom’s Mink, don’t you? You’re far more likely to be able to raise a good shine come spring if you remove the season’s stains now and protect the fiberglass from the ravages of winter with a couple of good coats of wax. Luckily, keeping your boat in tip-top shape is a lot easier than it was in the old days when wooden vessels called for scraping, sanding, and painting for hours on end. But don’t get too smug. There’s still a lot of work in your future, so let’s get started.

Step 1: Remove Oxidation

For the purposes of this article, we’ll assume you’re starting with gelcoat that’s slightly oxidized. If it’s extremely oxidized, you may need to call in a pro. If your gelcoat doesn’t show any signs of oxidation (yellowing and/or a chalky, dull appearance), skip to Step 2. Oxidation occurs naturally, as exposure to sun and weather break down the gelcoat’s surface and turn it chalky and pitted. If your boat is more than a couple of years old and hasn’t been meticulously maintained, chances are there’s some level of oxidation. The more there is, the tougher this step will be.

Make an «X» on your buffer bonnet with the liquid.

You need to hit every inch of the fiberglass with a good oxidation remover. As a rule of thumb, it’s best to use the least abrasive oxidation remover possible, so you don’t grind away lots of gelcoat. How will you pick which one is right? Test a few different products on a small section of the gelcoat to find the least abrasive product that still gets the job done. If you try to deoxidize the entire boat by hand, you’ll blow out your elbows; an orbital buffer is a must-have tool for this task.

Fit the buffer with a terry cloth bonnet, and pour a big «X» onto it with the oxidation remover. Then hold the buffer gently against the hull side with even pressure, and hit the power button.


If you accidentally pour too much oxidation remover onto the buffer bonnet, move down three or four feet and blob it onto the hull side. That way you can make use of it as you work your way down the boat.

WARNING: If you hit the power button before the buffer is sitting flat against the hull, it’ll spray oxidation remover in every direction.

Once the buffer is running, sweep it back and forth across the hull, going over the same area three or four times and being sure not to leave any gaps in your coverage. Never hold the buffer still, or it can «burn» a divot in the gelcoat.

You’ve hit the entire hull? Now look carefully for spots the buffer missed because there are always a few (under the rub rail, transom corners, and around thru-hull fittings, for example) and do them by hand. Then put a new bonnet on the buffer, and use it to rub off the oxidation remover. If the oxidation was severe, or if the remover you chose was too weak, you may have to repeat this step.

  • Acid-based cleaners are necessary to get out tough stains like rust streaks.

Step 2: Eliminate Stains

Once the oxidation is gone, there’s a good chance you’ll see a few stains. Let’s get rid of them. Most can be attacked with rubbing compound and a rag, but toughies like rust streaks will require the use of an acid-based cleaner. These are often marked «fiberglass stain remover,» but read the active ingredients to be sure some sort of acid is listed. Also be sure to limit their usage to where they’re absolutely necessary, and follow the instructions on the bottle; these cleaners can give off harmful fumes, burn your skin, and damage the gelcoat if you don’t thoroughly rinse them away after use. Be careful that you don’t rinse them into the water.

Step 3: Bring Out The Shine


Come spring, you’ll get an even better shine if you use one of those expensive microfiber polishing buffer bonnets for this stage, instead of the regular terry cloth variety.

Now we can polish the hull sides into tip-top shape. There are many good polishing products from which to choose, but this is not the time to opt for a combination polish/wax. That stuff is great for midseason touch-ups, but not for sealing out winter weather. Go for a dedicated polish such as Starbrite Premium Marine Polish. Apply the polish as you applied the oxidation remover, sweeping the buffer back and forth across the fiberglass until the entire boat has been covered. Let it dry, and then remove it. Whew! You’ve probably worked up a sweat by now, but we’re just getting started; you need to do the entire boat a second time, because one of the keys to making a boat shine like the sun is to polish it twice.

Step 4: Seal In The Shine

We’ll bet the glare coming off Mom’s Mink is downright blinding right about now, but if you stop working, the gelcoat’s finish will go back to being dull in a matter of days. You need to seal that shine in, and wax is the key ingredient. For this step, choose a paste wax that’s based on bee’s wax, NOT carnauba wax, which does create a better shine but also wears away faster. Again, you need to give the boat two thorough coatings of the paste wax, and unfortunately, this stuff gets applied by hand. Now for the coup de grâce: a coating of that shiny carnauba stuff. Apply it lightly and gently, so you don’t rub away any of the paste wax. Then clean it off with a final pass of the microfiber buffer bonnet.

  • Microfiber bonnets cost more than terry cloth, but for final polishing, they’ll make your boat shine brighter. Apply the paste wax by hand — this may take a while!

That was a lot of work, but a lot less than scraping, sanding, and painting. In the spring, you should be able to get away with a quick polish and then sealing in the shine. You can keep your boat looking red-hot all summer by washing it down with a wash-n-wax boat soap that contains a dose of carnauba. If you’re a perfectionist, renew the shine by giving the gelcoat another carnauba wax job every other week. And don’t look directly at your boat’s gelcoat without wearing sunglasses, or you might burn out a retina. If not, then it’s time to (sigh) go back to Step 1. 

Lenny Rudow is the electronics editor for BoatUS Magazine, and senior editor for

— Published: October/November 2013

How To Repair Fiberglass — Fiberglass Repair

Like Steel, Fiberglass Can Be Repaired … For Less Money, Time, And Effort

Few materials rival fiberglass. It has several advantages over steel. For example, low-volume parts made from it cost far less than steel ones. It resists more chemicals, including an abundant one that causes steel to whither away into brown dust: oxygen. Size being equal, properly made fiberglass can be several times stronger yet still lighter than steel. In fact, it won’t even dent.

No, when fiberglass does fail, it cracks. In fact, if hit hard enough, fiberglass breaks into pieces.

Steel snobs rejoice at that last part, but little do they know that’s where fiberglass really begins to shine. A seasoned veteran with a shop full of specialized tools might not be able to justify repairing a flat-smashed metal fender, but a rank amateur with hardly more than simple hand tools can put a fiberglass one back together from dozens of shattered pieces … sometimes in one afternoon.

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To learn how to fix it properly, we have to understand how fiberglass works in the first place. Depending on the construction technique, fiberglass resembles either a concrete slab or a sheet of plywood.

A slab owes its strength to the steel reinforcing bar, or rebar, embedded in it; the concrete is merely the glue that binds the bars and offers a conveniently smooth surface. Trade the rebar for a lot more glass strands, the concrete for considerably less plastic resin, and scale it down a whole bunch, and you’ve basically got a fiberglass part made with a chopper gun.

Wood plies bound together by glue create a panel far stronger than solid wood of comparable size. This construction forces individual plies to bear loads in tension or compression, the directions where most materials are strongest. We refer to fiberglass parts made by a similar bonded-ply technique as hand-laid or hand-laminated.

While more labor intensive, hand-lamination has serious benefits. First, it doesn’t require any special equipment like chopper guns, so it’s a real asset to occasional users. But most importantly, hand-lamination makes far stronger parts than any chopper gun could ever aspire to. It’s because fiberglass owes its strength almost exclusively to glass fibers and hand-lamination achieves a far better glass-to-resin ratio than a gun can. Remember that the resin exists only to bind the fibers. It’s comparatively brittle, and any more than necessary makes parts weaker and heavier.

This distinction is important for more than just selecting fiberglass parts; the hand-lamination technique is the backbone of most fiberglass repairs. Rather than merely joining broken materials at the point of damage as we do when welding metal, we literally grind away the damage and replace it with new material. By grinding the damaged panels in a particular manner, fiberglass repairs achieve great surface-area contact, which is essential to ply construction technique. What’s more, a properly made repair is every bit as strong as the remainder of the panel. In some cases-particularly with chopper gun-made parts-repairs made by this technique can be stronger than the existing panel. But best of all, any enthusiast with a few very common tools and a good supplier can repair fiberglass with the same kind of quality and reliability as a seasoned veteran can offer.

Though we can’t anticipate every type of damage, this method applies to 99 percent of all fiberglass repairs. In fact, this information applies to things like chopping fiberglass tops and grafting together two panels. Only the person doing the chopping is creating the damage. The repairs after the modifications remain largely the same.

While we don’t think you’ll intentionally create damage just to get the opportunity to try out this technique, merely knowing how to do it certainly eliminates a lot of anxiety. At the very least you’ll rest easy knowing that strong and reliable fiberglass repairs are easier than you thought.

A Word On Safety
Working with fiberglass-especially grinding the stuff-generates zillions of near-microscopic shards of glass. And those shards itch like hell when they work their way into your skin’s pores. The stories of itchy armpits and crotches make good bench racing. Only there’s nothing funny about those shards making their way into your lungs, which underscores the importance of quality protective gear. In that case, those shards can lacerate the sacs in your lungs causing an irreversible condition called Pulmonary Fibrosis. It reduces lung capacity and generally makes for a miserable and crippled life. Something as simple as a dust mask can go a long way to preserve quality of life. Better yet, use a painter’s respirator. Resin and acetone fumes might lend a stoney feeling to the day, but prolonged exposure can make you long-term dumb. Oh yeah, make sure your work area gets good ventilation. No respirator, no matter how powerful, will protect you in a fume-saturated workspace.

Resins and solvents also wick through skin like fruit punch through a paper towel and melt kidneys and livers as they leave the building. Latex gloves work great, and considering that constant contact with chemicals is inevitable you’re going to whip through gloves the way a jilted teenager goes through tissues.

Not even an eyeball hardly stands a chance. A chunk of fiberglass kicked up by a grinding wheel cuts like a flying razor blade. A single drop of the potent oxidizer used to catalyze resin splashed in the eye can permanently blind. Goggles are a good starting point, but don’t underestimate the comfort and peace of mind a full face shield offers. Prescription eyeglass wearers take special note.

There are also optional protective measures. Long pants taped to ankles and long-sleeve shirts taped to wrists may make you sweat, but you’ll appreciate not itching at the end of the day. Tool suppliers sell lotions that seal pores, preventing glass fibers from lodging into pores. Hats and bandannas keep your hair clean, and so on.

Make no mistake: Fiberglass is relatively safe when handled properly. It’s also capable of inflicting unspeakable pain. Treat it (and yourself) with care.

Polyester Resin
Nearly any polyester resin from a good supply store will work, but hold out for Iso resin if possible. Avoid surfacing resins for these types of repairs; the paraffin wax suspended in them lets the surface dry more completely but it wreaks havoc with paint and future laminations unless you sand the dried surface completely.

Like paint, fiberglass resin comes in several forms: polyester, vinylester, and several grades of epoxy just to name a few. While some of these formulations offer incredible strength and durability, J.B. Donaldson recommends the standby, polyester resin. “Yeah, the other stuff can be a lot stronger, but it can also be tremendously difficult to work with,” he cautioned. He noted that alternative resins often require very specific measurements (mostly by weight), mixing procedures, and temperatures to achieve their full strength.

“They can also make future work really difficult,” he added. While epoxy will stick to polyester resin (epoxy primer-sealers over raw fiberglass and polyester-based fillers), the inverse isn’t necessarily true. “You can’t just go over epoxy with polyester,” he noted. “It just doesn’t stick, which makes future repairs on a part that much more difficult.”

Like even the simplest enamel, even polyester resins come in several forms. Before we proceed, though, let us offer a word of caution: avoid resin sold at chain stores. Inexpensive resin-often brown, coagulated stuff-pours terribly, mixes terribly, and wets out materials terribly. It also makes brittle and weak parts when the stuff hardens-if at all in some cases.

Instead, find a plastics supply or a very good boat house, whether locally or by mail order. J.B. says to specify Isophthalic resin, often referred to as Iso or tooling resin. He noted that while Orthophthalic resins are adequate, they’re not nearly as strong as Iso resins, especially for the very modest savings. The price difference sometimes works in favor of the good stuff. My last batch of Iso resin, for example, costs less than the green can of stinky brown death at the department store and a third of the price of the stuff at the local parts house.

Supply houses offer something else that no box store can: service. A blue-vested associate can hardly tell you what aisle to find resin much less how to use it. Supply houses often have intimate knowledge of their products, whether firsthand or through their customers’ experiences, and can suggest other supplies and materials to make your work that much better or easier.

Dedicated shops also offer fresh materials, a big deal since even a virgin can of polyester resin definitely has a shelf life.

How To Catalyze Resin
Catalyst content is key to a proper cure rate and strength. Luckily most catalyst bottles feature dropper tops for fairly precise measurements. Refer to the resin-to-catalyst chart to get into the ballpark.

Resin cross-links or polymerizes in its own sweet time but heat can speed up the process. Large manufacturers use giant ovens, but very small doses of a really potent oxidizer called methyl ethyl ketone peroxide, or MEKP, causes a chain reaction that generates enough localized heat to cross-link the resin.

There’s a catch, though: this resin-to-catalyst ratio is very sensitive. Too little and the resin may not cure, too much will cause the resin to craze in an array of microscopic cracks that weaken the structure. Way too much, in fact, will start a fire. Making matters more complicated, temperature plays a similar albeit less-dramatic role in this chain reaction.

Chemical manufacturers rate their formulas to work best at 70 degrees F, or 21 degrees C, with 1 percent of their weight in catalyst. Neither figure is etched in stone. In fact, they’re inversely related: as one goes up, the other goes down. For example, resin requires less catalyst to polymerize in hotter ambient temperatures and more catalyst to polymerize in cooler temperatures.

Bear in mind this fudging has limitations. Less than 0.75 percent catalyst probably won’t polymerize resin; more than 1.5 percent will cause damage or a fire. This might be enough to extend your working range as low as 60 degrees F to as high as 95. “But don’t try to go too far,” J.B. warns. “Heat up your shop if it’s colder than about 60 degrees,” he instructs. My local supplier suggested building boxes to contain projects and warming the space inside with a heat lamp. Believe it or not, but it worked for me on a 40-degree day.

As tedious as this weight/volume ratio sounds, it’s not tedious in application. For example, eight drops of MEKP works out to 1 percent of an ounce of resin. Vendors know this and usually package small amounts of MEKP in squeeze bottles that conveniently dispense in drops. Use this chart as a working range. Remember to always use at least 0.75 percent catalyst and never exceed 1.5.

1 ounce 6 81012
4 ounces24324048
8 ounces48648096

We purposefully chose relatively small amounts in the chart to show the importance of mixing only what you can use within a 20-minute period. Even then, you’ll find it fairly challenging to properly use 8 ounces of catalyzed resin before it starts to set up in the cup. While manufacturers often mix by gallons, bear in mind that they use tooling and/or production methods that consume the materials far quicker than a bunch of us hobbyists can. Proper technique takes time.

One more thing bears mentioning when talking resin: mixing cup size. It sounds strange at first, but a given amount of resin will polymerize far quicker in a smaller cup than it will in a larger cup. It goes back to the heat: Concentrating catalyzed resin in a smaller container also concentrates the heat it generates. To get the longest pot life from your resin, mix it in wide, shallow cups. By itself that may double resin’s pot life without affecting its cure rate.

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