wasntme said:Nice write up but please allow me to inform you and the other members on a few things missed and incorrect.
First....fiberglass cloth and matte does not have shards of glass in it like fiberglass insulation. So it is perfectly fine to handle with bare hands in it's raw form...meaning has not been coated with resin. After it is have been coated it is BEST to use a respirator when grinding on fiberglass. Also good to do it a well ventilated area. Now hardened fiberglass can cause itchiness. This is from tiny fibers being embedded in the skin. If this happens I find the best solution is to take a very hot shower. As hot as you possibly can stand for 10 minutes or so. Then using a wash cloth or similar scrub arms in a downward motion. This will pull the fibers out...at least most of them. The hot waters causes the pores to open and release the fibers. Once done scrubbing switch the water to cold to close the pores.
In the tutorial you mention to apply a coat of resin once the first coat is hard but do not mention using a cloth with the resin. Resin should not be applied without using a cloth, matte, or filler agent mixed into the resin. Resin alone is brittle, provides no extra strength, and does provide extra useless weight. So if you were saying to apply resin only this is not a good idea. Also you said not to worry about how well the glass lays down. That is a HUGE mistake when doing a lay up (lay up means applying fiberglass resin to anything). When you are doing a lay up you should ALWAYS do your best to get the cloth to lay down as smoothly as possible along with NO air bubbles. The reason for this is the more time you spend getting the glass to lay down smooth the less time you will spend grinding on the glass. The reason for no air bubbles is because an air bubble is a weak spot in the final product along with a great spot for delamination to start. That is where the layers of glass start to separate from each other. Essentially making the item fall apart. Also when doing a lay up you only want to use as much resin needed to "wet out" the cloth. This means to fully saturate the cloth with resin but not have puddles or big drips. Again...this excess resin only serves as added weight.
A huge pointer is to not to mess around with trying to get fiberglass smooth. Fiberglass is intended to be the structural material. A good body filler (aka bondo) should be used to make the part smooth. I never sand fiberglass with anything smoother then 80 grit and that is being generous. Usually I use 36 grit and move onto the body filler.
No some info on resins and to answer a question from another member. You really should not purchase resin from Home Depot, Lowe's, or auto parts stores. Try to find a local boat supplier or fiberglass supplier. The reason for this is polyester resin has a short shelf life and you do not know how long it has been sitting on the shelf of the big box store. Also generally your materials will cost less if you purchase from a fiberglass supplier. A member asked about mixing resin with MEKP (the hardener) to go along with his climate. Climate is a HUGE factor when mixing the resin. If it is very hot outside or humid you need to use less MEKP then if it was very cold outside. If you use too much MEKP the resin can do many different things including catch fire. Too little MEKP and the mixture will never cure. I recommend doing a sample mix or mixes to determine the proper amount of MEKP to resin ratio. Also for giggles if you want make sure you do this OUTSIDE away from anything that could be ruined...mix a ratio of 1:1 resin and MEKP....then step way back. It will not exploded but it will get wicked hot, put off a horrible odor, and melt the cup it is in. Do this at your own risk but it will show just what will happen if you mix too much MEKP and resin together.
Just a FYI to everyone..Bondo is a company that produces auto body products. Body filler is a the actual product you want to use to get your parts smooth. I also suggest you find a local auto body supplier/paint supplier and purchase some high quality body filler instead of using the Bondo brand from Home Depot. Rage Extreme is my personal favorite but there are a few others that are much easier to use then Bondo brand. When I say easier to use I mean they are easier to spread because they are more creamy...compare cream cheese to mayonnaise...and they are easier to sand.
Someone also mentioned using old T shirts or grill cloth instead of fiberglass cloth. They also mentioned they used those materials in car audio. Well those materials were used in car audio for one reason only. They could be stretched and shaped around a form. Once the first coat of resin was applied to the grill cloth and hardened, additional coats of fiberglass cloth had to be layed down to give the item strength. I have personally used this technique hundreds of times and it works well in that application. In this application it would work very poorly. The reason being is you would spend for more time applying layer after layer of T shirt material or grill cloth to achieve the same strength as two layers of the proper cloth. Cloth will cost a few bucks more but will save tons of time and achieve a better final product.
I hope this info helps everyone and just a small tidbit about myself and where I have come up with this information. I have been working with fiberglass and body fillers extensively for the past 20 years.
what he said +1
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lol
