Ready to begin a fiberglass project? Make sure you learn as much as you can before getting started. In this blog post, we will discuss seven things that you need to know before starting a fiberglass project. By learning these tips, you'll be able to avoid common mistakes and have a successful project!
There are two main types of resin used in fiberglass projects: polyester and epoxy. Polyester resin is the most common type of resin used. It is less expensive than epoxy and is more forgiving to work with. However, it is not as strong or waterproof as epoxy. It comes in different grades including ortho laminating, ISO and finishing resin. Ortho laminating and ISO resin will cure tacky so you can do many layers without the need to sand in between. You will want to use a finishing resin or add wax to your final layer for a tack-free finish. Epoxy resin is more expensive than polyester resin and is known for its strength and durability. It comes with three different hardener speeds: fast, medium, and slow. Epoxy will cure with a hard, tack-free surface.
Polyester resins have a very strong smell. It is critical to make sure you have a well-ventilated area to work in. A proper respirator is also important. If you can't do your project outside, do it in an open space where air circulates, preferably with a window or door open. Epoxy resin also has a slight odor but it is nowhere near as strong as polyester and vinyl ester resins.
When working with resin, you will need to work fast. Not so fast that you do not mix and measure correctly, but fast enough that the resin does not start gelling in your mixing cup. Have everything ready to make sure nothing delays the resin process.
There are two main types of fiberglass: fiberglass cloth and chopped strand mat (CSM). You will need a good pair of scissors to cut fiberglass cloth or tape to size, but be aware that fiberglass will dull them quickly. Fiberglass is made up of glass filaments and can be harder on scissors than normal sewing fabrics.
Chopped strand mat can be cut or torn into pieces. It is very messy to work with. It is made up of short strands of fiberglass held together by a styrene binder. Those short strands can get everywhere so be prepared..
The ideal temperature to work with fiberglass is between 70-80 degrees Fahrenheit. If it is too cold, the resin will not cure properly. If it is too hot, the resin will cure too quickly and will be difficult to work with. Watch the weather if you are working outdoors and make sure you have several days in a row that will be in this temperature range.
If you are working in hotter temperatures, you will want to use less MEKP when working with polyester resin or use a slow hardener if you are using epoxy resin. If the temperatures are colder, the opposite is true. You will want to use a little more MEKP for polyester and a fast hardener for epoxy. Do not add more than 1 3/4% MEKP to your polyester resin and NEVER use more hardener to epoxy resin than is called for. Epoxy resin has to be mixed in exact ratios.
If you are working outdoors or in a garage, make sure your project is protected from the wind. Wind can add unwanted dust particles to your finished product.
It is important to keep track of the time when working with fiberglass. Resin has a specific curing time, so you need to make sure you allow enough time for it to set before moving on to the next step. The length of time will vary depending on the type of resin/ hardener you are using as well as the ambient temperature.
Have patience and work in small batches. If you rush and mix too large of a batch, the resin will start kicking off and maybe even start smoking in your mixing cup. This will cause a big unwanted mess and could also be dangerous.
It is important to clean the surface you will be fiberglassing. Any dirt, grease, or oil will prevent the fiberglass from properly adhering to the surface. You can use a solvent like acetone to clean the surface. Make sure you wear gloves and have proper ventilation when using these solvents.
Depending on the original surface, you may need to do some sanding first. You want the best bond possible between the fiberglass and your surface. If sanding is necessary, wipe away any of the sanding dust once you are done.
Fiberglass work can be dangerous if you do not take the proper precautions. Always wear gloves, goggles, and a respirator when working with fiberglass. The fiberglass fibers can cause skin irritation so it is important to avoid contact with your skin as much as possible. Inhaling fiberglass particles and resin fumes can also be damaging to your lungs so make sure you are in a well-ventilated area. Protect your eyes with safety glasses/goggles.
When ordering resin, it is important to know when you will start and finish your project. Resins have a shelf life, so make sure the resin is used during that time. Vinyl ester resin has around a 2-month shelf life, polyester resin has a 6-month shelf life and epoxy resin can last for a very long time if properly stored.
You will need to store your fiberglass supplies in a cool, dry place. Fiberglass cloth and chopped strand mat are both susceptible to moisture so make sure they are stored in an airtight container. Polyester and epoxy resins can also be affected by moisture so it is important to keep them tightly sealed when not in use. Resin must be stored in a cool, dry place or the shelf life will decrease.
These are just a few things to consider before starting your fiberglass project. By doing your research you are already on the right track. Putting in the extra time to choose the right fiberglass and resin, ensuring the ambient temperature is right, allowing enough time for the project, readying the work surface properly, wearing safety equipment and storing the resin correctly will help you have a successful outcome.
If you have more questions, don't hesitate to contact us.
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For our Ultimate Fiberglass and Resin Guidebook, you can go here- Ultimate Fiberglass and Resin Guidebook for Beginners - Fiberglass Warehouse
I’ve been wondering why fiberglass cloth isn’t used for backpacks? If you compare the specific strengths (tensile strength in comparison to the material’s density) of nylon 6 vs E grade fiberglass fibers, fiberglass has two and half times higher specific strength (if you use S grade fiberglass cloth, it will be 3.4x higher specific strength). If you are curious, E glass fiber glass’s ultimate tensile strength is 5.6x higher that of nylon 6’s, but again, when you factor in density and that fiberlgass is about 2.24x more dense than nylon, it does lower the overall strength to weigh ratio in comparison.
Besides its significantly higher specific strength as compared to nylon 6, it has other attractive properties. It doesn’t absorb moisture, it is not affected by UV at all, very high microbe resistance, it is inexpensive (especially when you buy in bulk–typically at least 16 yards), it can handle very high heat with no issues (unlike nylon), and it’s more stiff than nylon (which in a pack I think is a good trait because it will carry weight better).
The downsides are that the fibers are potentially irritating to the skin* with less flex durability than nylon. * To me, the former is a non issue because if you use fiberglass cloth, you have to encapsulate it within a bonding matrix of some kind, which for my purposes, I would use thinned silicone caulk (because of accessibility, expense, relative ease, and you can bond to other silicone coated fabrics). If there is a thick enough coating of silicone over the fibers, there won’t be any chance for the fibers to come out of their yarn and weave.
As to the second part of this, I think it is less important for a piece of gear like a backpack than it is for say clothes, tarps, tents, and the like, where the latter often get folded over, twisted, etc. repeatedly. In all reality, a pack only has to flex and fold a little here and there. Comparatively, it is a more static and homogeneous shape/structure/function.
I guess the other downside is that you would have to make the fabric yourself (treat the fiberglass cloth with silicone and/or silicone bond it to other silicone coated fabrics), but this is not a barrier to me or most DIY/MYOG type folks.
More specifically, why couldn’t you say, take a 2.1 or 3.7 oz/yd2 fiberglass cloth and silicone bond it to silpoly (for greater waterproofness and better sewing), and have the light weight silpoly fabric on the inside and the siliconized fiberglass on the outside? Silicone is considered to have significantly better UV resistance than nylon and even more than polyester, and as mentioned the fiberglass cloth is unaffected by UV and so, the material would last as long as the silicone does.
Honestly curious why something like hasn’t been done by people before? Am I missing something major?
Another cool thing you could do with fiberglass cloth, is if you wanted a very stiff framed, high load backpack, you take a piece of thin’ish plywood and bond fiberglass to it with high strength epoxy and for the rest of the bag that is meant to be flexible, you do the above of siliconzing it and bonding it to a silpoly. If constructed well, theoretically such a pack could carry very heavy loads well (good for hunters or the like).
Seems like a decent and more low cost alternative to UHMWPE fabrics. Besides the expense of these fabrics, bonding to them is very difficult unless they are specially altered by cold plasma treatments or the like. Not easy to do for the average DIY’er. Meanwhile, they need to have some kind of film or bonding agent otherwise the fibers can come apart within the weave (and for waterproofness). If inexpensive and bondable/already treated UHWMPE fabrics ever become a thing, then yeah, this would be the ultimate pack material, but meanwhile, if I’m not missing anything, it seems like fiberglass cloth/silicone/silpoly composite fabric would be an improvement over other inexpensive options as to strength per weight and especially long term durability (particularly due to very high UV and microbe resistance).