Repairing SMC and Fibreglass

The basics of SMC and Fibreglass repair (and replacement) are covered in this video. The intent of this video is to supplement my students’ learning within the Auto Body repair industry, weather working in a collision, heavy truck or restoration shop.
0:00 Introduction
0:20 SMC vs Fibreglass
0:58 Resins
1:55 Cleaning the Repair Area
3:23 PPE and Safety
3:45 Separating Panels
7:46 Panel Preparation (grinding)
8:35 Supporting the Repair
10:05 Cloth and Mat
11:28 Mixing Resin
12:29 Applying Resin
15:50 Over-catalyzed Resin
16:28 Preparation for Inner Panel Installation
17:43 Preparation for Outer (cosmetic) Repair
18:33 Filling the Cosmetic Repair
19:40 Discussing Primers & Gel Coat
21:36 Inner Panel Installation
23:12 Mixing Fibreglass Resin
23:56 Creating a Patch

[@ChrisLawley43]

Excellent video. I need to repair a crack on my hardtop that goes onto my jeep that i just bought.

[@StonnieDennis]

Thank you!

[@ryanflaherty3153]

I wish I had seen this before I did the glass work on my front bumper. Great info.

[@tdematteo01]

Thank you for this video. I decided to do some paint repair work myself on my truck, a Hummer H2, and and needed to sand the paint on the hood to remove some paint defects. I then learned it was a SMC hood and have been worried about damaging the outer film and getting into the mold release agents. I got this now. Thanks

[@AshsVaporeon]

It turned out amazing ! It's was a pleasure being able to see the process live 🙏 thank you

[@benh4086]

Thank you for the comments.

[@NavyPanther54]

Amazing dude. I need to do some SMC repair on my Fiero, and this really cleared some things up. My dad used to do autobody years ago, but he likes to take shortcuts or put his own twist on things, which has backfired on me a few times haha. So now that I know what's up, I'll be able to tackle it soon.

[@allankaul8331]

By far the most helpful and informational fiber glass video I’ve found while trying to learn how to make my own car parts

[@benh4086]

Thank you for the kind words. I hope you have success with your own projects.

[@williamblankinship9104]

Ben. I learned a great deal from this video. You are meticulous in your procedure and very clear on all your steps to repair this panel. This is by far the best video on fiberglass repair I have seen. Thanks for helping most of us understanding and applying your knowledge.

[@benh4086]

Thank you for the kind words.

[@ehss192]

10:20 Thanks. Great explanation!

[@jordanschroeder4703]

Great video. I can't believe this doesn't have more views. Over the years. I have watched a lot of how-to videos for various things in the automotive world. You cover all the bases and all the different scenarios. It was good how you showed what not to do by mixing too much hardener instead of just explaining verbally what it would do. This gives a very good visual of what to look for and avoid. Great work. Great video. Thank you.

[@benh4086]

Thank you for the kind words.

[@Imwright720]

This was well done. Thanks. One thing I noticed when you were talking about priming is you said the primer protects it. I thought fiberglass was waterproof already.

[@benh4086]

Thank you for the comment, and great question! The resin used in fibreglass repair is ‘waterproof’. However, the glass fibres themselves are not; they will wick/absorb moisture which ‘rots’ the fibreglass over time. The fibres become exposed when grinding, or if they are not completely covered in resin which is why priming is required.

[@olenaerhardt7725]

What product would you recommend to repair kind of brittle headliner board? I made one crack on removing it fm/the car and also it has some voids, which I want to smoothen before applying a new headliner cloth. I saw one film where the author used caulk (100% Silicon), but afraid the caulk might fell out in heat, maybe better to use some Bondo filler. Thank you for so informative film.

[@benh4086]

That depends on the damage. Are you replacing a small section, repairing a crack that is through to the other side, or just single sided. Resin with some matt or cloth would be good for a strong repair. Otherwise fiberglass reinforced filler or regular lightweight polyester bodyfiller may suffice for smoothing the surface.

[@olenaerhardt7725]

@@benh4086 Thank you for the replay. I have a crack similar to @ 17:51. I repaired today using superglue to keep it in place (masking tape didn't work well), then painted w/Fiberglass Resin, placing some pieces of Fiberglass mat. Since it is my 1st project w/Fiberglass resin I messed up a bit, some mat didn't attached, etc. I got a bulge on the side that goes to the ceiling ~1/4 in tall and ~ 2" in diameter. Can I live it like that (it gives extra strength I assume) or better grind it off to the smooth surface w/let say an oscillating tool and sand paper #80? Will it be visible if I leave that bulge? I would appreciate any opinion on this question. I painted the whole headliner board w/Fiberglass Resine: on the ceiling side it came very well, like plastic, you can hear sound if you knock on it. The other side is still drying. I'll cover it tomorrow 2nd time. Everything looks good, but that uneven surface on the ceiling side, not sure about it. Thank you again.

[@cordellstockdale3360]

Hey ben I was curious what adhesive was used for inner panel installation?

[@benh4086]

Hello. There are many 2-component epoxy and urethane products available to bond composite panels by manufacturers such as Fusor, 3M, SEM, and many others. I do not recall the exact product used in the video, but it may have been Fusor 147; though T21 would be a better choice.

[@timstanford3443]

Thank you for the video. The fiberglass reinforced filler, is this the regular long kitty hair? Thanks again!

[@benh4086]

The product in the video is referred to as short-strand fiberglass filler. 'Kitty hair' is long-strand fiberglass filler. The difference is the length of the fiberglass strands. In many situations, they could be used interchangeably. However, long-strand fiberglass filler will provide more strength, but short-strand is easier to work with and still provides excellent strength. I hope that answers your question, and thanks for watching my video.

[@timstanford3443]

@@benh4086 so I can use this for repair on SMC fiberglass?

[@benh4086]

@@timstanford3443 hi Tim. SMC and Fiberglass are two similar (but different) materials. The video discusses this at the 0:20 mark. The repair in the video is on an SMC panel using SMC resin. In short; yes, you can use this repair on SMC and fiberglass.

[@timstanford3443]

I understand i guess my question is can I use the regular fiberglass short hair filler on a similar repair? Thanks again for your help!

[@benh4086]

@@timstanford3443 Yes, you can.

[@chandranidas5924]

Can you please explain about the body fillers?

[@benh4086]

I have a video describing body fillers kzbin.info/www/bejne/gIGmlqqsqt5qpqc

[@powpow4033]

So what did you use under not to have resin stick on the parts you did not want to?😊

[@benh4086]

I used aluminum tape in the video; any form of aluminum can work well as the resin will not adhere. Thank you.

[@powpow4033]

@@benh4086 thank you. Do you know if the fiberglass resin wil adhere on the polypropilene pp plastic?

[@garylykins790]

I made a mistake and bought a urethane based adhesive by 3M instead of an epoxy based adhesive to use on the hood of my Freightliner. Can I still use the Urethane based adhesive if I go over it with some SMC fiberglass resin and matting?

[@benh4086]

Hi Gary, Make sure you identify the material that the hood is constructed of (quite likely it’s Fibreglass or SMC; however, it could be another composite). Then check your repair material to see if it’s compatible. if it is not compatible, then purchase the correct product. It is usually best to avoid mixing products during the repair process. If you have questions about specific products, I would suggest contacting the manufacturer (in this case, 3M).

[@matthewtolles4666]

What's easier to repair on smc. A crack or to rebuild an edge. And on each which product should I use mat or cloth?

[@benh4086]

What's easier is really dependent on the specific damage and the skill of the technician. Cloth and mat each have their advantages and disadvantages. Generally, mat is great for smaller repairs.

[@josecavada3830]

👍

[@chandranidas5924]

I couldn't understand the part where you were applying heat!!!

[@anilgunawardena9631]

Hi a 'm fiberglass technician u how any job thank u.

[@jackamo427327]

Do yourshelf a favor and go to epoxy resin and get a buble roller

[@bipedalhominid6815]

Its pronounced process not PROcess.

[@bubbajohnston]

Canadian