Fiberglass Resin - West Marine Epoxy or Bondo

rick3rd

rick3rd

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I am repairing the floor in my 1995 Monterey - I had a soft spot by the ski locker. Repair involves replacing some deck wood (stingers are fine).

I am miffed at the cost of the West Marine Epoxy Resin and Glass Cloth. I found that Bondo has resin and cloth for about 1/3 the cost - Bondo is intended for automotive repair. When comparing these two products I believe that they are basically the same.

Does anyone know why I should not use the Bondo product rather than the West Marine product?
 
rickryder

rickryder

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

uscomposites.com .... 435 std ploy resin is all you need plus some csm and cloth.

435 Standard Polyester Layup Resin
(Marine Grade Resin)
435 is our most popular resin for marine construction, repair and general automotive applications. Excellent for all types of fiberglass lamination, layup, and repair work. Good strength and nice wet out make this resin very popular.
Color: Dark Amber/Green
Cat No. Size Price
SM-435025 1 Quart $ 11.75
SM-435100 1 Gallon $ 30.50
SM-435500 5 Gallon $ 125.00

You will need to gelcoat over it when your done.... Lots of great info on here just use the search feature ;)

To answer your question about the Bondo stuff.....it has wax in it and you will need to sand between coats of glass and gelcoat.
 
U

UncleWillie

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

rick3rd said:
...West Marine Epoxy Resin ... I found that Bondo has resin and cloth for about 1/3 the cost ...I believe that they are basically the same....
Click to expand...

Apples and Oranges!

West Systems Resin is Epoxy.
Bondo Resin is Polyester Resin.
Epoxy is going to be more expensive.

Polyester sets up in minutes.
Layup Resins leaves a tacky surface that can be layered without sanding.
Finishing Resins leaves a hard surface that must be sanded if re-layering.
Auto parts store resins will amost always be finishing resins.
Polyester Resins tend to be more brittle than epoxies.

Epoxy sets slower, up to a couple of hours if needed, giving you a longer working time and can be layerd without sanding.
Epoxy will generally be stronger and will flex more before cracking.

Your boat is most likely Polyester.
Your Surfboard is likely Epoxy.
 
C

Chris1956

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

Polyester Resin and a piece of medium duty cloth is fine over plywood deck repairs. Epoxy is necessary for critical repairs, such as cracks in the hull. I use the West Marine poly resin on deck repairs.

The solids in lots of brands of automotive bondo is talc. Talc is unsuitable (IMHO) for marine use as it absorbs mointure.
 
Bob_VT

Bob_VT

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

The bondo brand resin is waxed. If you are doing repairs you really want unwaxed resin and the package of cloth that is normmally sold with the bondo resin is also inferior for boat work.

I will move this post to the restoration section and we have MANY fiberglass professionals that hang out there ;)
 
Woodonglass

Woodonglass

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

You stated that the stringers are OK. What have you done to ensure that they are ok? Boats usually rot from the bottom up and soft spots in the deck usually indicate bigger problems down below. If you have not core sampled the stringers, I would strongly suggest you do so and the transom too!! All the above about the resin is spot on!
 
Yacht Dr.

Yacht Dr.

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

rick3rd said:
Does anyone know why I should not use the Bondo product rather than the West Marine product?
Click to expand...

You can use the Bondo resin for deck repairs if you wish. Just get used to the Cure times as I have found its Very Fast :) .

Yd.
 
NSBCraig

NSBCraig

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

Yep YD's right it sure does kick fast.

But than sometimes that's cool, it's all about learning what your working with.

Check out Rickryders suggestion and try your local auto paint store too, that's where everybody gets resin around here and it works out better due to no haz mat shipping.
 
rickryder

rickryder

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

NSBCraig said:
Yep YD's right it sure does kick fast.

But than sometimes that's cool, it's all about learning what your working with.

Check out Rickryders suggestion and try your local auto paint store too, that's where everybody gets resin around here and it works out better due to no haz mat shipping.
Click to expand...

Most auto body supply shops have wax in their resin....
 
Cadwelder

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

Another problem with the local auto parts store, is the age of the resin.....polyester resin has a short shelf life and generally speaking the store doesn't have a clue how old the resin is....

I know I've asked the guys at West Marine (would never buy there, waaaaay overpriced) how long they've had these two cans of resin, and they said, I don't know but it's been sealed, so it's fine....WRONG!!!

CW
 
Scott Danforth

Scott Danforth

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

I have used Bondo resin in the past. it is waxed. I also recommend about 2/3's of their hardener which is MEKP with a carrier, or it will kick way too fast.
 
U

UncleWillie

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

NSBCraig said:
Yep YD's right. It sure does kick fast.
But than sometimes that's cool, it's all about learning what your working with...
Click to expand...

The working time is dependent on the temperature.

If the resin is in the 80 degree range you only have 2-3 minutes to mix and spread it.
At 95 degrees it may set up before you can get it mixed!

If you put the resin can in the refrigerator for 20-30 minutes before mixing, you can cool it into the 60 degree range and get 5-8 minutes of working time. :cool:

Once it is spread and mostly set, if it is cool in the shop, a hair dryer/heat gun can be used to speed up the process.
 
NSBCraig

NSBCraig

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

rickryder said:
Most auto body supply shops have wax in their resin....
Click to expand...

I've found the opposite, they don't offer any resins with wax in them and sell the wax on the side for when you need it. But then I lived surrounded by boat manufacturers so what you may find in your area can be different.

All you can do is check. It's definitely cheaper if you don't have to pay for hazmat shipping.
 
NSBCraig

NSBCraig

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Re: Fiberglass Resin - West Marine Epoxy or Bondo

Cadwelder said:
Another problem with the local auto parts store, is the age of the resin.....polyester resin has a short shelf life and generally speaking the store doesn't have a clue how old the resin is....

I know I've asked the guys at West Marine (would never buy there, waaaaay overpriced) how long they've had these two cans of resin, and they said, I don't know but it's been sealed, so it's fine....WRONG!!!

CW
Click to expand...

Definitely something to lookout for too!
 
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