The Central Hub for DSM Community and Information

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. This is where the DSM platform history is documented and archived. Log in to help us in our mission, and to remove most ads from the browsing experience.

Working with Fiberglass (FAQ)

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

MitsuReaper

20+ Year Contributor
383
0
Aug 3, 2002
home, Maryland
Ok alot of people have been asking me how to work with fiberglass. To make electronic mounts, gauge pods, hood scoops, hoods, fenders, just whatever.
So here it is.. I will make a FAQ section on my web page and load all of the new faqs onto it. this will be soon. :)

*Working with Fiberglass*
By: Allen G.
[email protected]



-Is fiberglass the right method for you?

Working with fiberglass is a very messy and time consuming process: Prepare area, lay fiberglass, wait for it to dry, sand/cut if necessary, lay more fiberglass, wait, sand, an so on. Once you are done with fiberglass, repeat the process with Bondo (car body filler) for finishing: Apply, wait, sand, reapply, wait, sand. It might take several days, even weeks to do a nice set of kick panels, subwoofer box or amplifier rack.

If possible, try to determine if you can use an alternate material such as wood and then shape using Bondo. Keep in mind that fiberglass is strong when bent. Straight fiberglass panels have to be very thick (read: time and money) for adequate rigidity. Sometimes a combination of wood, MDF or particleboard (for large flat sections) and fiberglass (for round, odd sections) works best.

-Materials

Fiberglass mat or cloth, resin and hardener.
Bondo (body filler), hardener.
(*Or Jelly Resin*)
Box of disposable gloves, respirator, protective clothing.
Paint brush, plastic sheeting, aluminum foil, mold release or WD40.
Tools such as sander, multi-purpose shears, screws, etc.
For small projects, such as gauge pods or Electronic mounts, you can buy all the supplies at a car parts store such as Pep boys. Products can be found at the "body repair" aisle. For bigger projects, supplies can get pretty expensive. Boat supply stores sell products in larger quantities, but at lower overall prices.

-Safety

Fumes and dust particles are a very important concern when working with fiberglass. Get a respirator or a dust mask designed to work with fiberglass. Wear gloves at all times when handling fiberglass and resin, or sanding. Protect ALL exposed skin, especially when sanding.
Fiberglass resin will make you high as a kite if you are exposed to it long enough.


Work in an open area! Resin/hardener mixture fumes are bad for your health. If you work with resin indoors, the smell will remain in the area for days. Do not handle fiberglass mat or sand dry fiberglass indoors. It causes rashes and itching.

Read instructions and warning labels carefully.

-Car Preparation

Before any work starts with fiberglass, plan the whole project. Look ahead into how you are mounting electronics, fastening the end project, paint finish, etc.

Once resin falls on carpet, upholstery, or other parts in your car, there is no way to get it out. Cover areas to be worked thoroughly. If possible, remove panels, seats, carpeting, etc in case an accident does occur. (If working in car)

Cover area to be molded with fiberglass with aluminum foil. Fiberglass can be laid over the foil and once it dries, foil can be easily peeled off.

-Making a Mold

If you are creating a shape in "mid air", you need to make a mold first. There are different options available. Some people like to make a frame out of aluminum foil and/or chicken wire. Other people use modeling clay or shape dried spray expanding foam.

Another option is to make a "skeleton", shape it with cloth and then fiberglass over it: Make a top and bottom part out of fiberglass, wood, plastic, existing car panels, etc. Join both with wood or metal braces. To fill the gaps, glue or staple sweatshirt material or pantyhose. Apply resin to the cloth or pantyhose. Once they dry, lay fiberglass over it.

The third option is to use an existing shape. (If working in car) After removing factory panels and carpeting, apply mold release, aluminum foil or WD-40 to surface (to avoid fiberglass from sticking). Lay fiberglass, and let dry.

-First Layer

First, mix resin and hardener. Only mix what you will need. It takes a lot of practice to get the resin/hardener ratio right. Too much hardener and it will dry right away, too little and it could take several hours. Temperature in work area also influences drying time. The hotter the temperature is, the quicker resin will dry. Also, keep in mind that resin will get warm when drying. You usually have about 10 mins to apply. After that the harder in the mix can that you are using will start to gel up, and then it is useless. Try not to use flimsy plastic cups or stirafoam cups. The mixture will eat right threw them.

Cut fiberglass mat to size. It is better to cut a bigger size than what you need for the first layer. You can always trim excess off when dry.

There are two ways to "wet" the fiberglass mat: By dipping it in the resin/hardener mixture, or by applying resin with a brush. Apply resin to the surface area first.
Then place the mat on the area that will "shape it". If you are a beginner, this might be a bit tricky. The mat will tend to stick to gloves and other stuff you don't want it to. Spraying some WD-40 on your gloves will help a bit solving this problem. This first layer would become the foundation of the piece you are building. Try patting the layer lightly with the brush to smooth it out. dont try to brush it untill it is completely covered with resin. The fully covered mat will look almost translusent.

-Additional Layers

Once the first layer is dry, remove it from the car. In most cases there is no need to work inside the car for subsequent layers.

Cut and sand excess fiberglass from fist layer, clean dust. Add next layers in same fashion as fist layer. Try not to have any gaps or bubbles between layers. You can use a cheap 1" brush to help get rid of bubbles. Do not worry about imperfections at this stage, you just want a rough shape with no major protrusions. All gaps and imperfections will be fixed at the last stage.

Shape and use of the object will determine amount of layers required.
Usually if there is not much stress on the object at all, 2-3 layers is fine.
If there is more stress more layers will need to be added.


-Bondo

Once you have a defined shape, no major holes and a pretty sturdy piece, you need to smooth out by sanding rough edges.

Bondo is very similar to fiberglass. Just add a few drops of hardener and drying process begins.
You want the mixed bondo to kinda look like a pinkish color. If it looks dark red or brown youve used to much hardner. If it looks a little darker than the actual bondo in the can, you didnt use enough hardner. You can also mix some of the Fiberglass Resin liquid in with the mixture. This makes the bondo very thin and really easy to apply.
Spread Bondo over you panel. Try to fill in gaps and valleys. Do not worry about smoothing it out much. Once Bondo dries, sand. Repeat the process as many times as necessary: Add Bondo, let dry, sand.

On the first steps, a power sander can be used to quickly remove excess material. On finishing stages, manual sanding might be required, depending on finish desired.

-Finishing

Finish smoothness depends on what material you are using to cover the piece up. Carpet is very forgiving when it comes to imperfections. Vinyl is less forgiving, you need a pretty smooth surface (a couple extra steps of Bondo might be required). If you are finishing with paint, then you do need a perfectly smooth surface.
If you are painting try to do these steps..
Primer (2 coats)
Paint (1 light coat, then 2-3 even thicker coats)
Clear Coat (atleast 2)
Make sure you let each stage DRY first before applying the next coats.
If you want a mirror shine, after the first coat of clear coat, lightly wet sand with 1,500 grit sand paper. Then apply another coat, sand. And so on. Do this for 3-4 Coats of clear. You will get a nice shine.
 
i can't emphasize the use of gloves, long sleeves and long pants enough. From working on a glass boat for a few years, i can tell you that fiberglass is not something you want on your skin. You will itch until it wants to stop, because pretty much nothing will get it all out of your skin.

That being said, fiberglass is fun, and not that hard! :)
 
I am modifying my spoiler that i got off of an acura legend. I took my friends stock spoiler from his 89 mazda mx-6 and put it upside down on the legend spoiler. Then i covered it with pantyhose instead of fiberglass and so far i have put 4 coats of resign on the top and 2 coats on the bottom. I am not done with it yet but next i am going to bondo up all of the rough spots and then put more resign over the bondo. Then i am going to sand it down real good and paint it. I am only about half of the way done with it. right now it looks real rough but i hope it turns out the way i want it to. It's hard to explain what it will look like but when i am done with it i will post pics of it in the gallery.
 
I've used fiberglass repair kits ever since I've broken my body kit twice, its actually quite fun. Gloves should be worn I agree, although it didn't make me itch it didn't come off very easily unless I used paint thinner/gasoline.
 
LOL you blew his spot hardcore :laugh:


i've been doing my front lip for about 2 months now and it's almost ready to debut here on the nonperformance forum :shhh:

all i can say is this: cover up your skin, use gloves, mask, and OPEN VENTILATION. i almost passed out one time cause i closed the garage. oh yea, it gets VERY messy.. LOL you should see my garage now:laugh:

right on brutha:thumb:
 
You may want to include ACETONE in to the needed supplies for clean up of brushes or whatever you get the resin on.
 
Add Value - Be Respectful - No Trolling - No Misinformation - Participate Often!
Support Vendors who Support the DSM Community

Latest posts

Build Thread Updates

Latest Classifieds

Back
Top