IPP Blog

IPP . . . YOU ASK . . . . WE ANSWER

At Industrial Plastics & Paints we take your questions seriously. Here you will find the answers to our most asked questions.

Considerations for Building Aquariums with Acrylic Sheet


Building an Aquarium takes planning and thought. Whether you decide to construct using Acrylic Sheet of Glass you  will still need to understand all the forces at play once you fill your tank with water. The information below is provided as a guide  by our sheet manufacturers to help you design your tank. However there are no warranties, either expressed or implied, by Industrial Plastics & Paints in offering this information.


Please click on the attachment below for an Excel spreadsheet which will help determine the proper thickness for an aquarium made of ACRYLITE® GP acrylic sheet.


 Click Here for Excel Worksheet mentioned above




Manufacturers recommend that all acrylic water vessels, including aquariums, should be constructed with Cell Cast Acrylic Sheet. This requirement exists for two reasons:

  1. CAST Acrylic sheet is more capable of withstanding continuous loads than continuously manufactured or extruded sheet.
  2. CAST Acrylic sheet maintains a high level of mechanical strength after water absorption has reached equilibrium.

Cemented joints must withstand the effects of the continuous hydraulic pressure and the high level of water absorption for many years.

Two-part polymerizable cements are recommended for your construction to meet this requirement. 


For proper cementing techniques Click Here.



To determine what thickness acrylic sheet should be used, the calculation below can be used assuming the base is uniformly supported.

T - thickness of sheet
H - height of tank
L - length of tank
Required Thickness T (in)=

q = maximum water pressure (lbs/in.2) = (0.0361 lbs water/in3)* H (inches)
H = aquarium height (inches)
α = maximum permissible stress for ACRYLITE GP in an aquarium (750 psi)
β = coefficient from L/H relationship as follows:

L/H 0.25 0.50 0.75 1.00 1.50 2.00 3.00 4.00
β 0.037 0.120 0.212 0.321 0.523 0.677 0.866 0.940

Note: For L/H ratios not shown, use the β value for the next higher ratio.


L = 36 in.
H = 15 in.
L/H = 2.4 therefore: β = 0.866 (taken from the chart for L/H = 3.0)
q = (0.0361 lbs/in3) x (15 in) = 0.542 lbs/in2

T (in) = = = 0.375 inches

If a top is cemented on, the recommended thickness in 0.375 inches. With an open top use a safety factor of 1.5, bringing the recommended thickness to 0.563 inches to be used in this size tank

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Using Epoxy Resin


While there are many sources of information on the Internet, none is better than information offered by the manufacturer of the product. They know how to get the best out of their product, it's limitations and it's strengths. Once you use these product you may develop your own techniques and practices, however beginners should follow the Manufacturer's instructions and recommendations. To that end, we offer links to videos and product Data Sheets for many of the products we offer on our website. The link VIDEOS will provide you access to instructional videos about many of the products we sell. Industrial Plastics & Paints stores offer the full line of both West System and System Three Epoxy. These videos provide great general information however, there may be some more technical questions for which they don't provide answers. In these instances I would encourage you to contact the experts in one of our store locations or submit your question to our website. 

Please remember that if you choose not to follow the manufacturer's directions they will be less likely to be able to help if you run into issues.

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1494 Hits

Can I Glue Polyethylene?


Can I Glue Polyethylene? . . . . The short answer is NO! . . . But there is more to the story

Over my 40 plus years in the Plastics Industry, I have been asked this question almost every day. So in preparation of writing this blog article, I jumped on the Web to see what answers others were offering to this question. I found plenty of forums with individuals offering a multitude of solutions to glue Polyethylene. I am here to tell you that while some of them may work to some degree . . . NONE of them work to the degree that most people expect. Oh there are surface preparations that will help industrial adhesives stick to Polyethylene but none will provide a permanent bond to Polyethylene. The only true way to bond Polyethylene to Polyethylene is by heat welding and this requires the right equipment and the proper technique.

The best bond between two pieces of the same material is a chemical bond, where the chemical in the adhesive melts the contact surfaces and they fuse together. That never happens with Polyethylene as the material is impervious to almost all chemicals. The only way to achieve this kind of bond with Polyethylene is with heat, melting the contact surfaces and pressing them together, or using a "like material" welding rod to braise the pieces together. In both of these cases the amount of surface area contact is directly relevant to the strength of the bond. For example if you are trying to bond the edge of a 3 mm piece of material to a flat surface, the success of your bond will depend on only 3 mm of surface area, and resulting in a weak glue joint doomed to fail. However if you are wanting to bond the surfaces of two 150 mm x 150 mm pieces of material together you would have 24 time more chance of a successful glue joint.

But wait, there are two more factors that affect the success of your joint. They are the direction of the force that will be applied to the joint and the amount of adhesive in the finished joint. The former is more likely to be more of a problem for an edge joint than it is for a surface to surface joint. The latter has a lot to do with the success of your joint, as a glue starved joint, has no chance for success. All of the adhesives that proclaim success in gluing Polyethylene will rely on a reasonable amount of adhesive remaining in the joint after curing. The common tendency is to tightly clamp the joint during the curing process. Where as this will push the adhesive out of the joint and leave your joint with two properly prepared surfaces and NO Adhesive. . . . providing Zero Chance for a successful bond! So if you do try one of these products make sure you follow the manufacturer's instructions. (see below for links to some of these products)

The success of gluing any material relies heavy on pre-gluing surface preparations on Polyethylene include chemical treatments and corona (heat) treatments both of these etch the surface providing a more porous surface that will help an adhesive find a mechanical bond. The use of one of these surface treatment on Polyethylene is mandatory if you want to give your repair any chance of success. But keep in mind what I said in the second paragraph, the amount of surface contact is directly related to the chances of success. Also if the reason for the original material failure is the amount of force that is regularly applied to the area requiring repair then your glue joint won't stand up. Example: gluing a small knob or hasp

The last thing effecting Polyethylene repairs is the age or amount of Ultra Violet light to which the material has been exposed. Polyethylene becomes less flexible and less resilient with age. Our stores have seen many Polyethylene Kayaks, Canoes and small Boats brought in to repair a hole or a crack. Often these items show signs of previous attempts at repairs with everything from silicone to blow torches. When we ask where the Customer acquired this craft . . . usually the answer is "I found it floating in the Ocean". . . Well who knows how long it has been floating around the world and most likely the original owner gave up on repairing the thing and rather than disposing of it responsibly simply turn it loose. However the fact is when these Polyethylene items crack or get punctured its is almost always because the material is past it's "Best Before Date". So while we can Hot Air Weld a patch over the broken area, the heat we need to apply will accelerate the aging process of the area around the repair, resulting is a new crack with any future impact.

Polyethylene is a super useful plastic, the fact that it is impervious to most chemicals and solvents makes it ideal for containers. It's hot flow characteristics make it great for Rotational and Blow Molding and it's flexibility provides a great deal of resilience to the products into which it is made. However it does have a shelf life and when that time has been reached, the best thing to do is recycle it!

Products we sell that boast successful Polyethylene repairs

West System G-Flex

Permatex Plastic Tank Repair 

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1365 Hits

Plastic Drums into Rain Barrels


Increasingly people have found a new use for our plastic drums. They turn plastic drums into rain barrels for their homes and gardens.

Rain barrels collect, or harvest, the rain as it falls and runs through your home's gutters and drain pipes. Turning plastic drums into rain barrels have several benefits for the environment. Today, we'll explore those benefits and how you can outfit a recycled plastic drum into a usable rain barrel for your home and garden.

Plastic Drums into Rain Barrels – Helping You, Helping the Earth

Rain barrels have several benefits. First, you capture a precious resource — water — to use in your garden during months when the rain isn't falling. This reduces your need to tap into a city's water supply saving you money and leaving more water for other uses.

You also help protect your local waterways by reducing storm water runoff from your home. Rather than rainwater rushing down a downspout or your driveway into the storm water system — and then right into the local waterways — you capture the rain and return it to the earth, where it's absorbed into the water table.

Rain barrels can last through decades of rainy seasons in your garden. The poly material is manufactured to withstand chemicals and other acidic materials and so will stand up well to rain, dirt and winter weather.

Making Rain (Barrels that is)

Turning a used plastic drums into rain barrels requires very little effort. First, you should make sure whoever you buy a used drum from has properly purged and cleaned the drum of its prior contents. (Our barrels are purchased from a reputable reclaiming facility) A rain barrel won't serve you, your plants or the environment if it still contains hazardous materials. Also, with this process these types of barrels should never be used for drinking water.

Secondly, you will want to make sure it has a secure, childproof lid to prevent any accidents. Lids will also prevent wildlife from getting in to the barrel and mosquitos, who love to breed in standing water.

Under the lid and with a little room to spare, install a piece of screen to catch debris as it flows out of the eaves-trough downspout. Debris in your rain barrel can clog the faucet or spout, making it difficult to use the water inside.

Choose a rain barrel with a hole in the lid that fits your downspout or cut a hole the appropriate size. Install an overflow attachment and hose near the top of the barrel as well. During the rainy season, the barrels fill quickly.

You will also need a faucet or spigot at the bottom of the barrel. Use a rubber washer next to the barrel, both inside and out, and a metal washer against the faucet on the exterior and the nut on the interior. The washers will help to keep the faucet water- tight.

Finally, position the barrel under the downspout on a platform. Cinderblocks work well for this purpose. You want to leave enough room to fit a bucket or watering can under the faucet. 

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1488 Hits

Compostable Bags


Compostable bags are made of natural plant starch, and do not produce any toxic material. Compostable bags break down readily in a composting system through microbial activity to form compost. Look for the BPI symbol to confirm that you are purchasing certified COMPOSTABLE bags

 Which bin? Compostable bags can be used to line your kitchen caddy for collection of food scraps and then placed into the green lidded food and garden organics (FOGO) bin. Don't waste them in your general waste bin as they will not compost well in a landfill environment. Due to the relatively low production these bags a currently more costly than Polyethylene plastic bags, however they can be used as carry out bags for retail stores and end their life in your compost collection bin.

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1611 Hits

Others Pail in Comparison - The Virtues of Plastic Pails


There are tons of types of containers, and there isn't a single one that can take care of all of them. What makes a container useful, however, is versatility. Of the containers regularly available for both private and industrial uses, the most versatile out there is arguably the plastic pail. This is a container that can pretty much do it all as far as regular jobs go, which is why we're always skeptical when we hear someone talking against them. Sometimes advice can be dead wrong, and here are some of the wrongest we've heard about plastic pails.

Plastic Pails aren't as Versatile as Other Containers

If anyone has ever told you that plastic pails aren't as versatile as other containers and because of this should be avoided, you need to avoid that person instead. Plastic pails are in fact one of the most flexible, versatile, and capable containers available, and that doesn't just mean for industrial uses, either. While containers like reconditioned steel drums and glass jars are great for their own functions, you'd be hard pressed to find a container that can handle as many different things as a plastic pail. Food grade plastic pails are commonplace in restaurants and hospitals, as well as in homes for large events. Plastic pails can also be prepared to be able to handle corrosive materials and other hazardous substances, if treated properly.

This of course is in addition to the industrial uses of plastic pails, from transporting to containing. However, what it can contain is as important as what it can do once it can no longer be used as a container.

They are Difficult to Take Care of After They Expire

This advice should be taken with an industrial sized grain of salt and a couple shots of penicillin for good measure. Plastic pails are, as the name indicates, plastic. This makes them very durable, even after they are no longer fit to contain things.

While plastic pails can very easily be recycled and reconstituted, they can also be quickly and easily changed to serve any number of other functions. They can be turned into molds for construction work, used for school projects, and even altered to serve as tools for gardens. With plastic pails, you don't actually have to get rid of them once you're finished—you can change them into something else and they just keep on going.

Plastic pails are some of the most versatile, durable, and reusable containers out there. They're incredibly convenient and they can take on a variety of jobs, which is why you see them everywhere from the meat locker of a restaurant to the beach where it's being used to build sand castles. They live long lives and serve their purpose well, whatever it is you might need them for, and once they've run their time they just keep on giving. Plastic pails might not be for every job, but if you're not doing anything too out of the ordinary you can bet safe money on plastic pails being able to handle the job. Friends don't let friends bad mouth plastic pails. 

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1263 Hits

Food Grade Plastic


 The media often paints all plastic products with the same broad stroke. After all, all plastic is made from hydrocarbons derived from petroleum or natural gas. So, plastic is plastic is plastic, right? Actually, no.

While all plastic does come from petroleum or natural gas, the processes involved vary and affect the purity level of the finished product. That fire truck you just tripped over the eighth time varies significantly from the plastic in your garbage can, and, more importantly, from the plastic in your water bottle.

Any plastic that comes into contact with something humans will consume including beverages and food is held to a much higher standard than other forms of plastic. So, let's take a look at what we mean when we use the term "food grade plastic."

Food Grade Plastic Regulations

The government develops regulations regarding food grade plastic. In Canada, Health Canada oversees these regulations. In the United States, the Food and Drug Administration (FDA) creates the regulations.

Both agencies, however, have similar requirements. Food grade plastic must meet certain standards of purity. It cannot contain dyes, other additives or recycled plastic products deemed harmful to humans. Food grade plastic can contain some levels of recycled materials as long as those materials fit the guidelines and regulations outlined by the regulatory agency.

Additionally, some foods leach additives from their containers and these foods, particularly acidic foods, must go into more product specific containers.

Types of Plastic

All plastic products in the U.S. or Canada carry a symbol with a number on it ranging from 1 to 7. These numbers mean the same thing in both countries. Not all types of plastic, though, are suitable for all types of food.

Many food grade plastic containers fall into the high density polyethylene — or HDPE — category. It has excellent chemical resistant properties making it suitable for a wide range of foods and other products.

For example, most juice or milk containers and five gallon food buckets are made from HDPE. In the U.S. and Canada, HDPE products have the plastic code 2.

Another common form of food grade plastic is polyethylene terephthalate or PET/PETE. These carry the plastic code 1 and are often used for products like salad dressing, peanut butter, and jelly jars.

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Watts vs Lumens


A 60 watt light bulb requires 60 watts of power to put out approximately 800 lumens of light. In contrast an LED light requires about 8 watts to put out 800 lumens. This makes conversions difficult. Below is a generic conversion chart that gives an idea on what LED bulb you need to replace an incandescent bulb.

                         Incand            LED

450 lumens  -   40 Watt    -   6-9 Watt

800 lumens  -   60 Watt    -   8-12 Watt

1100 lumens -  75 Watt    -   9-13 Watt

1600 lumens - 100 Watt   -   16-20 Watt

2600 lumens - 150 Watt   -   25-28 Watt 

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2768 Hits

Paint vs Re-Gelcoating

Paint vs Re-Gelcoating

This Verses has been going on for a long time and I have seen many mis-informed opinions in many Internet forums. This article is intended to provide that facts and then let you decide which one you will choose. So lets start with a little background about Gelcoat. 

Gelcoat is a cosmetic layer of Polyester Resin, thickening agents and colour pigments. It's sole purpose is to provide a quick, smooth, high gloss finish to production molded boats and marine watercraft. It has a consistency is like gravy and has NO self leveling qualities. Gelcoat is used in the manufacture of production Fiberglass boats that are fabricated using a female mold. It is applied using special spray equipment. The Gelcoat layer is the first to be applied to the inside of the mold once the Mold surface has been treated with a release agent. After this Gelcoat layer has cured to a tack, layers of fiberglass fabric embedded in polyester resin are applied to this layer. This is done in several succeeding layups until the desired thickness of the structure has been achieved.

So now lets talk about what can go wrong when mixing and applying Gelcoat.

  1. You apply the Gelcoat too thin - Blotchy appearance when cured
  2. You apply the Gelcoat too thick - Risk Spider Cracks in future
  3. You under catalyst the mixture - Gelcoat does not dry
  4. You over catalyst the mixture - Gelcoat "Kicks Off" before you can apply it (30-45 minutes)
  5. You don't apply three 10 mil coats - see #1 & 2

Now lets assume that everything has gone well and you have successfully applied 3 coats to achieve an overall thickness of 30 mils. No matter how carefully you applied the Gelcoat by brush and roller, you will need to do a lot of sanding to achieve a uniform gloss and appearance with the original Gelcoat. For the finest finish, you'll want to wet sand through 1,000 grit before compounding. Make sure that each grit has removed the scratches from the previous grit. Don't move to the next grit without thoroughly rinsing. A wet surface won't allow you to see fine sanding marks, so dry the surface and inspect it before moving to the next grit... Once you've reached the end of your sanding, the 1,000 grit will have brought your surface up to a dull luster. A course rubbing compound shouldn't be necessary and you may be able move to a fine compound like 3M Finesse-it. Follow the Finesse-it with an automotive finish sealant such as Meguire's Machine Glaze. This is followed with a swirl remover such as 3M Perfect-it & a foam pad.  

OK so that is the Gelcoat Process and here is the Painting process. Use a good quality marine urethane such as Interlux Brightside which has excellent application characteristics and yields that “sprayed on” look when brush applied in thin coats and is ideal for use anywhere above the true waterline. Brightside Polyurethane is easy to clean, resists staining and has great abrasion resistance. A hard, high gloss one part polyurethane finish. Please note that the "above the waterline" disclaimer refers to boats that spend most of their time in the water, trailered boats can use this product on the hull. If the boat lives in the water then an antifouling coating would be appropriate.

In closing I should point out that using gelcoat to repair minor dents and scratches is not as arduous as described about, however matching the original gelcoat colour can be a challenge due to aging of the original surface.

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16218 Hits

Epoxy vs Polyester Fiberglass Resin

Epoxy vs Polyester Fiberglass Resin

Before epoxy came on the polyester boat repair scene in the mid 1980's, most fiberglass boats were repaired with polyester resin. The repairs were typically successful if done by an experienced repairer.

Thirty-five years ago, fiberglass boats were overbuilt by today's standards. Many boats were built primarily with chopped strand fiberglass and polyester resin. Chopped strand fiberglass is not very strong compared to the woven fabrics and stitched oriented strand fabrics used more recently. However, hulls made with chopped strand fiberglass and polyester resin were built quite thick, which produced hulls that were very stiff and heavy. To repair these laminates, the technician would grind away damaged laminate and sand a gradual taper around the perimeter before laminating with new fiberglass and polyester resin. Acetone was often applied to the sanded area and was thought to soften the polyester resin and improve the bond between the existing laminate and the repair resin. Whether or not this improved the bond strength is debatable.

Polyester resin chemistry has changed over the years. Because many hulls are built thinner today and are more flexible, they are more difficult to repair effectively, especially with polyester resin. Laminates built with the new polyester are more difficult to repair because the resin cross-links more completely during cure. This means fewer bonding sites are available for primary bonds to form during a repair. A few boatbuilders using new polyester formulations are now glass tabbing in their bulkheads with epoxy instead of polyester resin. Because epoxies form superior secondary bonds, they do not have a problem adhering to properly prepared, cured polyester.

Comparing epoxy and polyester 
Polyester resin and epoxy resins differ in a number of ways. Polyester resin (often referred to as boat resin) is still used today to build most production fiberglass boats because it is the lowest cost option for new construction when combined with fiberglass reinforcements. Polyester resin can be quite brittle so randomly oriented chopped strand fiberglass is typically used between layers of woven or stitched fabrics so loads can be effectively transferred between the structural fiberglass plies. Without the chopped strand, micro cracks can develop over time in the resin between structural fiberglass layers.

Polyester resin is normally air-inhibited, which means it typically remains uncured (sticky or tacky) on the surface when exposed to air. To cure reliably, general-purpose polyester resin needs to be applied in at least 15 to 25 mil (.015" to .025") thickness. It is not very effective as an adhesive (partially because it will not cure thoroughly in thin films) and is only marginally effective as a repair resin for repairing well-cured polyester/fiberglass laminates. Polyester resin is not recommended for repairing vinylester or epoxy laminates.

Epoxy is used very effectively as an adhesive, as a laminating resin for wetting out structural fabrics, and as a coating. It has excellent thin film cure characteristics and resists micro-cracking better than polyester resin. Epoxy offers 3.5% to 4.5% tensile elongation at failure compared to 1% to 2% for typical polyester resins. It offers excellent moisture barrier qualities when used as a coating. It adheres to many different substrates including wood, metals, cured polyester laminates, vinylester laminates and epoxy laminates. It binds extremely well to graphite fibers, which is why it is often used for making high-strength graphite fiber composites.

Epoxy is more versatile 
Polyester resin manufacturers recommend that their products be cured in temperatures above 60°F. Repair yards often have to work in much cooler conditions. Extra MEKP (methyl ethyl keytone peroxide) catalyst can be added to assist the cure in cool temperatures, but cured physical properties suffer because of it. Shelf life of general-purpose polyester resin is six months to a year from the time it is manufactured.

Epoxy is routinely used to repair structural damage to fiberglass boats over a wide temperature range. Hardeners are available for curing it from 40°F on up. Shelf life of most epoxy is several years.

Epoxy has fewer fumes
Fumes from polyester resin are quite strong and flammable. Fumes from Epoxy are slight in comparison and not a fire hazard. However, both polyester resin and epoxy are industrial chemicals and should be used with care.

Epoxy is stronger

The the repair effectiveness of Epoxy and a DCPD (dicyclopentadiene) blend polyester resin have been compared on well-cured DCPD blend polyester/fiberglass laminate. Made of multiple layers of stitched 2315 triaxial fiberglass with mat, this laminate represents what you would expect to see in one side of a cored-composite, high-quality fiberglass boat. The cured fiberglass panels were prepared and repaired using methods described in 002-550 Fiberglass Boat Repair & Maintenance. A precise 12:1 bevel was ground along one edge of the laminates and the repair area was final sanded with fresh 80-grit sandpaper. (12:1 is the minimum bevel angle recommended for repairing cured composites.)

Different repair resins were used to apply multiple layers of fiberglass (the largest ply first, each ply separately laid and wet out with resin) to gradually fill the beveled sections to achieve the original thickness (see sketch). The repair was allowed to cure for a few days and then the repair zone was sanded perfectly smooth. G-10 fiberglass laminate tabs were added to both ends of the tensile specimens, providing a grip area for the test machine. The samples were allowed to cure for two weeks before being cut into 1" wide samples for testing.

To measure repair effectiveness, we first needed to determine the strength of undamaged DCPD blend specimens. The average tensile strength of the undamaged control laminate was 26,198 PSI.

The breaking strength of this same laminate after being repaired with polyester resin and the same fiberglass fabrics averaged 18,460 PSI or 70.5% of the original strength. In this case, the same resin used to fabricate the DCPD laminate was used in the repair. If a different polyester resin were used for the repair, it would likely not have performed as well.

The breaking strength of the control laminate after being repaired with Epoxy and the same fiberglass fabric averaged 21,404 PSI or 81.7% of the original strength.

Both repairs were done using the minimum recommended 12:1 bevel angle. Longer bevel angles at 15:1 or 20:1 will yield even higher repair strengths.

Epoxy shrinks less 
These were fairly small repair specimens compared to repairs often undertaken in the field. Some experts believe that the larger the repair, the more important it is to use epoxy. Their concern is related to the shrinkage that occurs in polyester resin. In a small repair, shrinkage is fairly insignificant. As the size of the repair increases, especially when a large section of laminate is being replaced, the shrinkage causes the repair to be stressed before the structure sees any working loads.

Forbes Aird in his book Fiberglass and Composite Materials provides a good description of what can happen in a bond line when polyester is used as an adhesive. He says that polyester has a volumetric shrinkage of about 7% during cure. Because of this, a bond line is subjected to significant stress which will occupy or use up a substantial fraction of the resin's bond strength even before subjected to any working loads. So, the 70.5% repair effectiveness for polyester identified in the testing becomes something less when used for large-scale repairs.

Epoxy is the better choice for repairing fiberglass boats. It has excellent adhesive qualities, wets out fiberglass fabrics and it is tough. It has great thin film cure characteristics, cures in cool temperatures and has a long shelf life. Like thousands of boat owners who have successfully repaired their boats, you can use Brands like WEST SYSTEM epoxy with complete confidence for fiberglass boat repair.

West System's Epoxyworks 22 / Winter 2004

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58810 Hits

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