How To Fiberglass Your Door Panels
This is a step-by-step guide to how I fiberglassed my door panels and added speaker & tweeter pods. I spent lots of time on forums and researching before I began this project, and I hope that this tutorial will save others time and money.
I. Overview � The Process
Now, this tutorial will show you how I fiberglassed my door panels, but I have also tried to write it general enough that the information can be applied to almost any fiberglass projects you may wish to undertake.
II. Tools and Materials
There are several materials that you will need for fiberglassing. You may not need all of these, depending on your application, but this is everything I used.
Materials
- Fiberglass Resin & Hardener (MEKP)
- Fiberglass Cloth/Mat
- Fiberglass Roller
- Body Filler
- Fleece or Stretchy Fabric
- Acetone
- Cheap Brushes
- Latex Gloves
- Measuring Cup
- Aluminum Foil
- Masking Tape
- Mixing Sticks
- Mixing Bowl
- 1/4" MDF Board
- 1/4" Wooden Dowels
- Plastic Spreaders
- Sand Paper
Tools/Equipment
- Staple Gun
- Fiberglass Mask
- Hot Glue Gun
- Dremel
- Sander
Fiberglass Resin & Hardener (MEKP)
This will be used with fiberglass mat/cloth. It is a liquid substance, and once hardener is added it will harden up and take the shape of whatever you apply it to. The resin shown below was ~$30 at Wal*Mart (3.5l). I�d suggest getting the larger size, since you will go through the small ones pretty quick, and it will be cheaper to buy in bulk. The hardener will come with it in the top. I�d suggest picking up an extra tube or 2 of hardener. What they give you never seems to be enough.
Fiberglass Cloth/Mat
This is what will actually give the fiberglass its strength. It will be used with the resin. It is ~$4 @ Wal*Mart, probably cheaper at a marine store or online.
Fiberglass Roller
The roller is used to roll the mat/cloth smooth and to avoid air bubbles.
Body Filler
This will be used after you fiberglass and sand to fill in any small imperfections. You can see the hardener on the right side. Many people will suggest better fillers such as Rage Gold.
Fleece or Stretchy Fabric
This can range from an old t-shirt to some fabric bought at Wal*Mart, JoAnne Fabrics. You want stretchy material so it can wrap around whatever your going to fiberglass. This is what you will apply the resin to. You do not want it to heavy, as it will soak up a lot of resin and cost you more money.
Staple Gun
This will be used to staples the fabric around the surface. For some jobs it may be easier to use hot glue.
Acetone
You can soak your brushes in acetone between layers of fiberglass to keep it from getting hard.
Cheap Brushes
Use the cheapest brushes you can find, since you will throw them out afterwards. I suggest cutting them short, about 1”, since these will be used to apply the resin, and the shorter they are, the easier it will be to apply.
Fiberglass Mask
This is very important! Fiberglass particles/fumes are no joke. Spend the money and make sure you mask is approved for fiberglass use. Do not simply use the cheap little dust masks! The mask pictured below was $50 from Ace Hardware.
Latex Gloves
Wear these when dealing with resin and painting. Don’t want to get it on ya. You can pick up a big bag of these for a few bucks.
Measuring Cup
This will be used to measure out the resin when mixing it with hardener. You will want a cup that has ounces.
Aluminum Foil & Masking Tape
If making a mold, you will use these 2 items to cover the area. Fiberglass resin will not stick to them, so you can apply the resin to it to make a mold of whatever u want.
Mixing Sticks
You can use just about anything, it will just be used to mix the hardener with the resin. I used those free paint sticks you can get at paint stores.
Mixing Bowl
This bowl or container will be used to mix the resin and hardener. You will then work out of it to apply the resin. I use cheap plastic cups or containers.
Hot Glue
This will be used to glue in the dowels for the speaker ring, and also to glue the cloth. You can pick this up for a few bucks at Wal*Mart or any craft store. Also pick up an extra bag of glue sticks.
¼ “ MDF Board
This will be used to make speaker rings. I did not make speaker rings for this project, but used some that came with my speakers. For directions how to make these rings, check out this website -
http://web.njit.edu/~cas1383/proj/mdf/index.htm
¼” Wooden Dowels
These are used for mounting the speaker rings. You can go either thicker or thinner based on your applications. Should be ~.30-.60 cents at Wal*Mart or any hardware store.
Dremel
This is a great tool to pick up if you are doing projects. It has a million attachments that can be used from cutting, sanding, sharpening, ect. Check Wal*Mart or your local hardware store.
Sander or Block & Sand Paper
Used to sand down the fiberglass, which you will be doing a lot of. The paper pictured is very fine, but you will be using course paper for most of your sanding (40-60 grit).
For information on painting, check out my How To – Repaint Your Interior.
III. Getting An Idea of What You Want To Do
This step is very important. This tutorial will cover how I did my door panels. What you want to do may be different, but you should be able to follow the general idea. These ideas should also be able to be applied to other pieces you may want to fabricate or fiberglass.
Here were my goals for this project.
1. I wanted to make pods in each door to hold a 6.5” speaker and tweeter.
2. I wanted to cover the lower pocket on the door.
3. I wanted to fill in all the lines to make the door smooth.
4. I wanted to recover the fabric on the door.
If you only want to do one of these steps, then just skip over the other sections. This will be a lengthy tutorial, since I will discuss the steps to accomplish each of these goals.
IV. Making the Door Pods for the Speaker & Tweeter
Here is a door panel which I modeled mine after.
Now that you know what the speaker pods look like, here is what we need to do to make them.
First you need to figure out where in your door you will put them. For better sound imaging, you will want them as low as possible. The reason for this is that when you sit in a car, one speaker is much closer to you than the one on the other side of the car. To improve your soundstage, you want to make the distances from each of these speakers to you as close as possible. The best for doing this is kick panels, but speakers in the lower part of the door are a close second.
In my door, I had a hole from where the speaker was mounted originally. Before I could begin making the pod, I needed to cover the hole.
To do this, I used paper to trace the shape. I cut a few pieces and taped them together. Once I got the shape of the area, I then transferred it to a foam poster board and cut out the shape. You could use cardboard or just about anything else instead if you wanted.
I then hot glued the poster board in place and stapled it. Now at this point, you need to decide where to put your speaker and how you want it angled. I suggest testing out the sound in your car with the speaker mounted at different angles before you proceed. You will then hot glue pieces of dowels and a speaker ring to give the mount a skeleton. I used a plastic ring that came with my speakers, but some people make wooden rings out of MDF. While holding the speaker approximately how you want it to be placed, take a tape measure and get a rough estimate for how far off the door it is. Then cut a piece of dowel this long, hold it on the door with the speaker ring on top. Adjust the dowel length and angle until you are happy, then hot glue it onto the door. Repeat this a few more times until you have a few dowels in place. Then hot glue the ring on top.
I had to cut a hole in the foam poster board to allow the back of the speaker to fit. Now, repeat and do the same thing for the tweeter. Also, I suggest doing both doors at the same time. This way, you can make sure they are identical.
I aimed the speakers up towards the opposite passenger in the car, so that the sound would cross in the middle of the car just in front of the people. I aimed the tweeters at the dome light. To make sure these lined up exactly where I wanted, I used a piece of string. I connected it to the place I wanted it to aim, and then to the door, so I knew exactly how to angle them.
I suggest hooking up the speakers once you think you are satisfied and testing them out. If they sound good, proceed. If not, do some work to make them sound how you would like. Also, make sure the pods are sturdy, since they will need to hold up when we stretch fabric over them and apply resin to them.
V. Wrapping the Door Panels
The next step will be to wrap the door panels in cloth. The material should be stretchy so that it can form around the speaker pods, and not too thick because it will soak up more resin.
First we must remove the handle, fabric insert and weather stripping. I did this because I am rewrapping them in a different fabric. If you were going to fiberglass them into the door, you can leave them on. The door handle is held in by a bolt underneath, and 5 bolts on the backside. The insert is held on by clips on the backside. The weather stripping is held on by staples on the backside. They must be pried out.
At this point, you can loosely wrap your fabric around the door panel.
The first time I did this, I attempted to staple the fabric to the back. It was difficult to get the staples to stick into the plastic. I soon figured out that it is much easier to use hot glue. It works way better than staples. For this reason, I suggest gluing a small section, then continuing around the back of the door panel. While you are doing this, you will want to stretch the fabric tight over the door panel.
Once you have glued the fabric around the entire backside, you can start stapling the outline shape. I did this where my handle goes down, around the speaker pods, and a few other places. I wanted to keep the general shape, but fill in the lines and the pocket at the lower corner of the door. So I basically outlined the door in staples. I also added a couple of screws with washers in a few places (made them flush with the door). This helped me put staples in without tearing through the cloth.
The next thing I did was to cut out the fabric where it needed to be cut and wrap it around the back. I also used hot glue to attach this.
Once finished, I did a test fit on my pieces to make sure they would fit.
Now before we move on, make sure that you have stapled everything that you want. Also, test fit the panel on the door and make sure that it will close with no problems. If any of the cloth comes in contact with the door, you will need to fix that, otherwise they will not fit once you apply resin. The shape you have now will pretty much be the shape of your door. Once your happy, move on.
VI. Applying the First Layer of Resin
After all that setup, we finally get to start the process of fiberglassing. First off, make sure you are in a well-ventilated area… preferably outside. Also, please make sure you wear a mask that protect against fiberglass particles. The fumes and particles given off are not good for you at all. This step may be a little messy, so make sure you cover anything you don’t want to get resin on, since you won’t be able to get it off.
The following is a suggestion based upon my experiences with this step. After I resined the door and let it dry, I had some slight fitment issues. These were due primarily to the door panel slightly shrinking and warping when the resin dried. To avoid this, I would suggest applying the first layer of resin while the door panel is attached. This way, the resin would dry to the exact shape that you want for the door panel. I feel this will avoid a lot of hassle. If you choose to go this route, make sure you cover any area of your car you do not want resin on, since it will be very hard to get off. Also, I would suggest not applying resin around the screws (that attach the door panel to the door). This way you can remove the door panels once the resin dries, then apply resin to the screw holes.
Another idea is to apply the resin to the door panel, and let it dry for a little bit until it is no longer dripping. Then you can attach it back to the door to let it fully cure (dry). You can choose what you think will work best for you. With that said, here’s what I did.
Pour some resin into the measuring cup. For smaller areas, I’d suggest only mixing up a few ounces at a time. But since this door panel is a much larger area, I mixed up 6 ounces at a time. I’d suggest starting out small, and moving up if you need more. Once you have measured out how much you want to mix up, pour it into your mixing bowl. The add drops of the hardener. The instructions for Bondo suggested 12 drops per ounce of hardener. Add a few more if you would like it to harden faster, or if it is cold out. Mix the hardener and resin together. Then take your brush and use jabbing motions to apply it to the cloth. When you run out of mix, simply mix up a new batch and continue until you have the whole area covered. I think I used 4-5 batches per door panel.
The darker areas are the places where the cloth actually touched the door panel. The lighter areas do not touch. I left these out for a few hours to dry.
Once the panels are dry, go ahead and fit them back on the door. Hopefully they will fit very well if you have taken the proper steps up to this point. I did have some fitment issues, due to the fact that I was not careful with checking to make sure the door panel fit before I resined it. These next few steps will hopefully not be necessary for you.
As you can see from the pictures below, part of the door panel came in contact with the lower part of the dash on both sides.
I was originally going to reshape the door panel to fit, but I liked the shape of them too much. I decide to cut out a section of the lower dash where the panels were hitting. I did this using a dremel with a cutting attachment. The plan is to later make a mold of the door panel where it was hitting the dash, and fiberglass that piece into the dash, so it will be flush with the door panel.
Another issue that I had was the fact that I did not have power windows. This meant that I had a window crank, which had to be removed. I am planning on converting to power windows, so I will be covering the hole. For this, I removed the window crank with a dremel and a cutoff attachment.
As if I haven’t had enough problems… like I said earlier, I had fitment issues due to the fact that the door panel shrunk when the resin dried. In order to make sure the door panel was flush, I added 3 brackets to each door panel on the inside.
VII. Applying Mat
For this step, I used fiberglass mat. You can also use fiberglass cloth if you would like. Whatever material you use, this is where the fiberglass actually gets its strength from, not the resin.
First you will cut you mat up into small pieces. You will want to cut all of your mat up before you begin, so you will not have to mess with it later. Some people prefer to tear the mat. In doing this, the edges become frayed and they will mesh together very well. I find it much messier to work with mat when I tear it. When I use the jabbing motion to apply the resin, I find that I can mesh the edges of the mat together very well. I find the smaller the pieces, the less chance of air bubbles. Pieces of the size shown below worked well for me.
The next thing you will want to do is mix up the resin and hardener like you did before. This time I suggest mixing up smaller batches. I used 2-ounce batches for smaller areas, and 3-ounce batches for large, open areas. Once you have your resin mixed, paint some onto your surface. Then lay a piece of mat down, load up your brush, and jab the resin into the mat. You will want to completely saturate it. Then lay down another piece and continue this process. Once you run out of resin, mix up another batch and continue.
You can apply up to 3 layers of mat at a time before letting it dry. I used 1-4 layers on the door panel. More around the speaker pod because it needed strength, less around the edges because they needed to be able to fit. Depending on what you are building, you may want to use more. As an example, a sub box typically needs 7-9 layers of mat.
VIII. Sanding
Ok, the dreaded sanding. This part of the process will probably take you the longest. The fiberglass is hard, and will take a while to sand and shape it. I started out sanding with 60 grit, but you should be fine to use 40. It will help shave some time off. I used a sander on any parts that I could, and block/hand sanded what I could not reach.
Your goal of sanding is to smooth out the surface and get the shape that you want. This will require a lot of time and patience. During this sanding process, you will develop many pits. Don’t worry about these. We will fill them in with body filler in the next step. The most important thing here is to remove any waves that you might have, remove any air bubbles, and get the shape that you want.
Don’t be afraid to go back and fiberglass after you sand if you see an area that needs some more support, or needs to be reshaped/filled in more.
Before I moved on, I cutout the holes for the speaker and tweeter. I used a dremel with a cutoff wheel. Once I cut close enough to the edge, I sanded the edge until it was flush.
IX. Applying Filler Mixture
Once you have your piece sanded down and you are happy, you now have to fill in those pits to make a smooth surface. For this we will use body filler. Below I will explain how to simply use filler, or how to mix up a “milkshake batch”. I attempted the milkshake batch, but found that just using body filler worked for me. The milkshake batch came recommended by many people though, so you may want to give it a shot.
It is called a milkshake batch of body filler since that is the consistency of it. To make it, you use 2:1 resin to filler, along with their appropriate amounts of hardener (this means you will use twice as much resin as you do filler). You may want to use slightly less hardener to give you more time to work. Once mixed up, you will have a milkshake like consistency. Using either a flexible putty knife or a brush, spread this out over the entire surface. You will want it to be a few mm thick, basically enough to fill in all the pits.
If you wait for this mixture to dry completely, it will be a lot of sanding. Instead, you will want to do some sanding while it is drying. Wait until it is no longer tacky to the touch, but not completely hard. At this point, it is much easier to sand than when it is completely hard. Take some course sand paper (60) and sand off the high spots. You do not want to do all of your sanding at this point, but simply getting rid of the excess will be easier at this point. Then let it fully dry.
If you decide not to use the milkshake batch, that is ok too. If you are just using filler, you will want to follow the directions on the can. Basically, you will mix appropriate amounts of body filler with hardener, and spread it out over the surface. The smoother you make it, the easier it will be to sand. For Bondo filler, the directions suggest using a 1 ¼” strip of hardener for a golf ball size of filler. Mix the two together thoroughly on either a piece of glass or some cardboard and apply it. I used red hardener, so when mixed with the filler, it should turn a pinkish color. Lighter and you may not have enough hardener, darker and you may have too much. You will only have a few minutes to apply it, so work with small batches. You should be able to sand the filler after about ½ hour.
Once it has cured, then you can go ahead and sand. You will work on sanding down the high areas, and sanding out any pits.
Don’t be afraid to repeat this step if needed. When you are done, you should have a smooth surface. Sometimes your eyes may not be able to catch this, but you will definatly see it once you primer it. A good suggestion is to get a piece of cloth and run it over the panel with your hand while your eyes are closed. You will be able to feel much better where the bumps and valleys are, and if you have any waves. The panels above are not complete and still need more filler/sanding.
Also, if you have any small pits or pinholes, you can apply glazing putty as a final touch to fill them in. Just follow the directions on the package.
There are a few more things I would like to add to this, but I am graduating college and moving, so I will not be able to work on these again for a few weeks, but I wanted to be able to post it up to help you guys out. Looks for some updates in a few weeks, and let me know if you have any problems.
In the future, I will add pictures, instructions for steps on finishing these up, along with instructions on how to rewrap some of the pieces in different material.
FAQ:
Can I just fiberglass over plastic?
No. Resin will not stick to plastic. If you want to fiberglass over plastic, you will need to drill a series of small holes all over the surface. Then you will apply resin to both sides of the surface, so the fiberglass bonds to itself. Then you can fiberglass as normal.
Can I fiberglass over vinyl? Like on my dash and armrest?
No. To fiberglass an area like this, you need to tear the vinyl off, and you will be left with plastic. Follow the hole drilling routine that I just discussed.
Help! I applied my resin + hardener mixture but it won’t get hard.
You did not apply enough hardener. For Bondo resin, instructions suggest 12 drops of hardener per ounce. Read the instructions on your resin and use the desired amount. If it is cold out, you can use a few more drops, or if you want ti to dry faster, but warning, your work time will decrease. If your mixture does not become hard, scrape it off and reply a new batch to the surface.
How do I fiberglass if I am not covering something (like a door panel)? Like if I want to make a mold (like to make kick panels or fit a sub into a corner of a trunk).
You will want to completely tape off the area or object with masking tape. Tape way past what you are working on so that you don’t get resin on anything else. Then aluminum foil over the tape and tape the aluminum foil in place. Now apply your resin and mat over the tape/foil. Once it dries, you will have a mold of the area or object. Remove the tape/foil and continue on.
Do I need to apply mat/cloth? The resin seems pretty hard.
Yes you do. Fiberglass gets its strength from the mat/cloth, not from the resin. You will notice that with just resin you can push on the piece and it will flex. Apply cloth or mat until the piece doesn’t flex. Like I said before, a few layers works for smaller applications, where sub boxes usually take 7-9 layers of mat.
How do I prevent/fix air bubbles?
Air bubbles occur when the mat/cloth lifts off the surface. To prevent them, I suggest using small pieces of mat/cloth. Bigger pieces tend to have more trouble with air bubbles. Also, when you see them begin to form, load up your brush with resin and jab them. If you missed some and they dried, sand them down to remove them and rework the area where they occurred.
Can I just use body filler (like bondo) instead of resin/mat?
You can, but you will regret it. Body filler is to be used as the last step, only to fill in small holes. If you try to use it to replace resin/mat, it will crack and not have the strength of fiberglass. Below is an example of someone who thought it was a good idea to use body filler in their entire trunk.
X. Thanks/Contact
I hope this tutorial was helpful. I acquired the information from this from several sources and message boards. I made many mistakes along the way, and I hope others can benefit from them. Thanks to anyone who helped me out. If you have any comments/questions, feel free to contact me. I have a version of this in Word, so e-mail me if you would like a copy.
Jbody.org: SliMMaTiC (Tom Sylvester)
E-mail: tsylvest@gmail.com
Aim: siimmatic
Wide Body Progress
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