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Fiberglass 101

36K views 118 replies 12 participants last post by  manicmechanic 
#1 · (Edited by Moderator)
Hood Automotive tire Vehicle Automotive lighting Bumper
Motor vehicle Wood Automotive exterior Automotive tire Hood
Hood Motor vehicle Wood Automotive exterior Vehicle
Well, to start. I searched for several years for a hood for my 38 Plymouth. I could not find one and decided to build a fiberglass one made from a cardboard template. I had started the template when I found a hood in South Dakota. It had been hit with something and was pretty beat up, but better than cardboard. I will spend a lot of time fixing it and getting it straight enough. But I have more time than money.
I have to learn things by reading or doing. Someone can tell me how to do something and I will forget it before I turn around. So to start I picked up a book on Fiberglass mold and part making, started cruizing the internet and trying to decide which way to go. I live in the NW and am near several boat building sites. So I was able to find a Fiberglass Store local to get all my supplies from.
My hope is that you may learn from my journey into the Fiberglass area. I am a novice at this and if anyone seems me screwing up or has some helpful comments for others, please chime in.
 
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#2 ·
Thanks for starting the fiberglass thread Mike! Looking forward to seeing the process! I've got a pretty ugly rear bumper on the Falcon, and I'm thinking about pulling it off and hitting it with the torch to straighten it up. Then make a mold and pop out a fiberglass rear bumper for the car.
 
#4 ·
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So, please do not think that the items I am going to use, means you need to use them. You can use different items, not use items or any number of comnbinations and probably get a good mold and final product. However, these are the ones that I have selected and will be using. The book is one that I selected and was good. Safety items include Tyvek or paint coveralls with a hood or a pull over hood seperate. The rollers and covers can be picked up at any hardware store. The shims are specially made to work with the fiberglass, but I think almost anything like these would work. The bottle with the funnel looking thing is a trick measuring device for the MEKP (hardner for the resin)
 
#5 ·
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You will need some special tools (oh good an excuse to buy tools!) The rollers are not very expensive, about $10 each or less. I read that you can use PVC pipe coated with release agent for rolling out the resin instead of buying the roller covers. I am going with the recommended items. Release agent in the bottle and wax in the can. You could use a different wax and probably have, but again I want to use the recommended item the first time and hope it comes out right. The blurry picture is the tool gel coat used for the mold. Also the MEKP. It is some bad stuff so use care in handling and make sure not to spill on yourself. Thats why I like that measuring cup, you just squeeze it and it fills the dispenser without splashing.
 
#6 ·
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And last but not least is the resin. I am using tooling resin for the mold. It is strong and also less expensive. When I make the hood I will use vinyl ester resin which has a bit more strength and also more heat resistance. I have a formula for determining the amount of resin needed. I think it should be pretty close to the 5 gallon pail I got. This will also let me see if I can cut back on the amount I need for the hood and save a couple of dollars. I also picked up some chopped strand mat and coremat. A friend donated some fiber cloth to me. So I am set for most everything I need. Except one. It needs to be around 65 degrees for the fiberglass to set well. I may have to wait a month or so to let it warm up here. I can't use my shop heater due to the open flame. Just remember this stuff stinks and is flamable. Use a respirator and have good air flow.
 
#10 ·
Yep, the fiberglass store and the book both warned that the MEKP is some bad stuff to mess with and to be careful in storage and disposal methods to prevent the fires and other generally bad things from happening. And we do not mean to scare you, but just be aware and use sound safety procedures. Yes that means you need to read the MSDS warnings!
 
#13 ·
To make a mold, you need a part to make it from, referred to as a buck. In my instance, if you are making a hood, if you had a good one, you could wax it up and use it as is. Most molds are called female molds, since the part is laid inside of the mold. To get a mold, you need to decide how thick you want it and what material you will use. Chopped strand mat or mat as it is called adds bulk, but not a lot of strength. Fiber cloth gives the piece its strength. To start, once you have your part you want duplicated. You wax it with at least 3-4 coats of wax. After the wax has set, you spray on PVA seperator. It is like a spray on plastic bag and helps get the mold off your part you started with. After the PVA, then you can spray, roll or brush on the tool gel coat. Then start layering your mat and fiber. You need to ensure you allow time for each layer to set up before putting down the next. You should always put mat on the gel coat followed by whatever filler you decided on. Make sure if using fiber cloth or coremat that you put a layer of mat in between them to help level them and give the resin some bite. Mat should also be the last layer. Each layer should be cut out and set in the order they will go on near your work area. Leave about 2 inch overhang for the mat and cloth on all edges. Once it has all cured, usually a couple of days, unless you have a big oven, then you can pull the mold off your original part. It was recommended to me to use 3/4" plywood as supports for the bottom of the mold. This also allows it to set flat when you trun it over to lay up your new hood. I was also told to make sure and leave a gap of about 1/8" between the mold and the wood to allow for expansion of the mold. Several strips of fiber cloth can be used to attach the wood to your mold.
 
#14 ·
It's amazing how hot the mix can get when it "turns over". It's hot enough to feel hot through gloves!
I used the PVC pipe method also Mike! A friend put me onto buying the cheap rollers and then one 10' length of the correct sized PVC pipe, and just cutting pieces off to fit the roller handles. The good part is just tossing them when done, and grabbing a new piece the next time, but I doubt they roll as well as the finned ones that you got.
 
#15 ·
After you have pulled the mold from your buck, you will need to start work on the mold surface. This is going to be the face of your new part, so you want it pretty. Any nicks or gouges you can fill with bondo and feather out. Once again, break out the wax and give it 3-4 coats. If you are not using PVA then they recommend using 8-9 coats of wax. Once you have the mold prepped, you have a stable location and the mold doesn't move, you are ready. Make sure you have all your layers of fabric or mat cut and laid out. Remember to leave 2-3 inches of excess on all sides. You will be using unwaxed gel coat on this. Waxed gelcoat is typically used on the exterior of projects, such as boat hulls. The unwaxed is used when you gel coat can cure without any air (such as when you are using a female mold). Spray or roll in your gel coat, then start with mat and work up to the thickness that you want. Let the part cure and then pop it out using the plastic wedges. You may need to shoot some compressed air in between that part and the mold to help break it free. Once out, continue to let it cure for the recommended time period before you do anything to the final surface. I will be photoing the steps as I progress. I am almost done prepping my hood, so once it warms up a little more I should be getting started.
 
#16 ·
MD...... You are off to a GOOD start..... with this thread I know I will be adding "making fiberglass parts" to my Opel's "to do list".

Thank you so very much !!!!!!
 
#17 ·
Mike, when it comes to waxing your mold I found it best to start with a mold sealer. I would put the sealer on, and wait the its recommended time before I wiped it off and then wait over night before I put any releasing agent on. I like the liquid releasing agent, it's a semi-permenant which attaches it self to the mold. It takes three coats max. How I would check it is, I would take a ten inch long piece of tape and stick it to the mold and watch it curl or be able to drag it sideways. The problem with paste release is it wairs out quickly. If you do apply a paste release the time you leave it on is just as important as how long you wait between coats.
Another tip, make your part, or your Buck perfect, with no imperfections because you don't want to have to repair a new mold. If you make your hood your molding off absolutely with no flaws, nicks and other imperfections, every part you pull will be perfect, and that also means mold longevity.
The way you are planning will work fine, I just got use to the liquids and never went back to paste. And I relies you are only pulling so many parts, but if the opportunity presents itself to build hoods for others you will want the least amount of work after pulling the part.
 
#22 ·
...... Mike..... you are only pulling so many parts, but if the opportunity presents itself to build hoods for others you will want the least amount of work after pulling the part.
This is going to be a very interesting and informative thread.... so much so I am sure many members like me will attempt to do the same as you are doing Mike.

The small items I made with fiberglass (tubes for frenching 62-67 Vette tail lights) were much more simple to do compared to the hood you are making for your Mopar Gasser.

All it did is to wrap what I used for a "mold" with plastic and once the fiberglass hardened it slipped right out.

I know it might too early to ask but how much do you estimate project "Fiberglass 101" to cost you for materials..... of course the work & time you'll be putting into this adventure of yours is "PRICELESS".

Detailed threads like "Fiberglass 101" really help novices like me to "think I can".

Thanks again !!!!
 
#19 ·
Only one year, 1938 and only on the Plymouth. Each of the grills are different per year and by brand. Pain in the rear. It would have helped to have had a better hood to play with, but I about have it licked now. I would have had to do the fiberglass anyway because the hood is hinged in the middle and cutting a hole for the intake would have been a disaster. Something I always wanted to try, so here we go.
 
#20 ·
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This last weekend I got the hood pretty straight with guidecoats of primer. I sprayed some rattle can gloss (blue) on and found I still had a bunch of spots that needed attention. Got those leveled and sprayed another coat of color (red)on. Left it to dry and called it a day. The light spots you see are the bodyfiller showing thru since I didn't use a primer/sealer on it. Once I wax it, it will not affect the gel coat finish. I am going to sand the color with 600 grit to get it smooth.
 
#23 ·
Well, so far I left $300 at the fiberglass shop. But I got some new tools and goodies that I can use on the second half of this. The tooling gel coat and tooling resin will probably be used up. The mat should be enough to at least start the hood. I have to buy ester vinyl resin and gel coat when I get ready to make up the hood. Probably around $500 total (combined with earlier 300). You can buy a good fiberglass hood for around $300. So you benefit from them having all the material there and the speed with which they can make it. But when you got something no one makes, well then it costs more and you probably have to do it yourself. Find some buddies that have left over cloth and mat to donate to you, that will save some money. Resin to if it isn't too old.
 
#24 ·
I got a call last night from a friend who has an Austin like mine, but his is the pre-War 1941. He had two rear fenders built for his that are 2" wider than stock. He aalso had a glass trunklid built. He's moving to Hawaii this year, and is cleaning out. He said he found two extra fenders, a trunk lid, and the molds for all three in his storage building. He wants me to buy them all for $125. It's a great buy, but not sure I'd ever use the parts or the molds, and space is a premium here! If they were for the more common A40 I'd jump on it, and build some parts to resell.
 
#26 ·
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I was able to get to the hardware warehouse and get some 3/4 inch plywood. I am going to use the left over protion for a worktable for layup. I used my cardboard template to trace an outline on the wood. I will use this when I cut out my mat and fiber. The I cut up my template and used it on the hood to trace the outside surface and then cut it out to match the curve of the hood. I then transferred it to the plywood and cut out the rear and front template to be used for support of the mold. The hood turned out pretty well.
 
#27 ·
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These are the wood supports front and rear. I sanded the hood one last time and started putting on coats of Partall #2 wax. I got on 6 coats and ran out of energy. Probably do a couple more coats next weekend and then powerbuff it. Still waiting for it to warm up. I may have to crank up the heat and then just go for it. Weather man says 40's to 50's and rain all next week. I did get a undercoating gun to use for the gel coat.
 
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