Bow Eye Repair Leads To China Syndrome From Resin

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Author Topic:   Bow Eye Repair Leads To China Syndrome From Resin

cheepskater posted 05-01-2010 06:48 PM ET (US)
[In] doing my first bow eye replacement on a [1962] 13-foot Boston Whaler boat, I removed the old eye, as well as some foam, and had a nice hole, which I assumed was ready to fill. Basically it's a hole through the boat at this point. I read about the bow eye repair (on this site and everything was helpful), but I'm doing something wrong. I taped off the outside bottom of the hole (with a plastic packaging tape), and began to fill with a [mash] made from West Systems 105 Epoxy with the 206 hardener. This is what I did for other holes and it did not create heat. I lined the inside bottom of the hole with 3M Marine Adhesive 4200. Before it dried--I'm thinking this is where I make the mistake--I filled the hole with mash and actually laid whole fiberglass on top as I filled the entire hole. It was looking great and I'm thinking I'm almost finished when I notice smoke coming from the hole. So I panic, grab a screw driver and take out everything best I can. The material was hot and looked like I installed too much fiber.
[Next,] I cleaned the hole, tried just 105 and 206, again with mesh a fiber whole pieces, but I [did not] fill that much. Same [result] is happening. [There is] heat and I are afraid it's going to create a fire. Tell me what I'm doing wrong. Thanks, cheepskater.
contender posted 05-01-2010 07:50 PM ET (US)
[Advice about hardener ratios deleted--jimh] Clean out the 3m4200 redrill the hole to clean it out and remove all the loose material. Use a product like superbond epoxy adhesive. It's a mix that is 50/50. It will look like a thick off-yellow paste. You need to find yourself a large syringe or a tool of this nature, mix the epoxy, place it in the syringe, and squirt it in the hole. Using a syringe; you can force the epoxy in all the way in the hole and you can do this from both sides to fill it properly. At the same time force all the air out of the void. I would use some type of tape, or, if you can, set something up to block the hole on the hull side to prevent the epoxy from running out. Figure this out before you mix and shoot the epoxy in the hole. Good luck
jimh posted 05-01-2010 10:20 PM ET (US)
The chemical reaction between epoxy resin and its hardener is an exothermic reaction. The greater volume of reagents used, the more heat is produced. If you mix up a large volume of pure epoxy and pour or inject it into a void, you can create a lot of heat as the reaction takes place.
The rate of reaction increases with heat, so as the reaction warms the reagents, the reaction rate increases, producing more heat, which in turn increases the reaction rate, making more heat. As you discovered, the reagents can get very hot. Enough heat can be produced to melt foam and other plastics.
You should use epoxy resin as an adhesive, not as a filler. Mix the resin with a filler material. Fill the void in the hull in stages, not all at once.
Jerry Townsend posted 05-02-2010 01:19 AM ET (US)
[Gave a reply that assumed a polyester resin was used with a catalyst hardener. This was not the case.--jimh]
jimh posted 05-02-2010 08:53 AM ET (US)
To contender and Jerry'--The resin used was specified as WEST System epoxy, not polyester resin. The ratio of resin to hardener in WEST System epoxy is not a matter of a few drops, but is more like 3:1.
Any large concentration of curing epoxy will generate substantial heat. You do not need to fill the entire volume of the bow eye hole with new material. Just built up the hole until its diameter is smaller than the bow eye threaded rod. If there is a large void at either end of the hole, build up this area with epoxy resin thickened with filler material in stages. If you pour a cup of curing epoxy down the hole, it will generate too much heat.
contender posted 05-02-2010 11:11 AM ET (US)
Jim:.. I found this under West System Epoxy...[Long cut and paste without attribution deleted.]
jimh posted 05-02-2010 11:38 AM ET (US)
The curing of epoxy is a chemical reaction. The speed of the reaction is not influenced by the amount of either reagent being in excess of the stoichiometric ratio. The speed of reaction is influenced by temperature.
jimh posted 05-02-2010 05:20 PM ET (US)
WEST System epoxy is not cured by a catalyst. The two reagents of the reaction are mixed in their stoichiometric proportions and turn into a new compound. The reagents should always be mixed in the proper proportions. An excess of either reagent just produces a diluted epoxy which will not be as strong or cure as well. This is why WEST System sells mixing pumps and pre-sized mix packages.
The heat that was created was not due to using too much hardener. You simply had too much epoxy concentrated in a small area.
cheepskater posted 05-02-2010 06:44 PM ET (US)
Thanks alot for your help everyone. Today I tried again and used the premixed WEST epoxy and hardened and only put small amounts at once and basically have been doing small amounts at a time. Thanks for the assistance it helped a ton.
dfmcintyre posted 05-03-2010 08:56 AM ET (US)
Another way to do that type of repair (deep hole) and avoid excessive exotherming, is to use the West epoxy that's slow reacting. The extra slow hardener is 209.
Regards - Don

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Author	Topic: Bow Eye Repair Leads To China Syndrome From Resin
cheepskater	posted 05-01-2010 06:48 PM ET (US) [In] doing my first bow eye replacement on a [1962] 13-foot Boston Whaler boat, I removed the old eye, as well as some foam, and had a nice hole, which I assumed was ready to fill. Basically it's a hole through the boat at this point. I read about the bow eye repair (on this site and everything was helpful), but I'm doing something wrong. I taped off the outside bottom of the hole (with a plastic packaging tape), and began to fill with a [mash] made from West Systems 105 Epoxy with the 206 hardener. This is what I did for other holes and it did not create heat. I lined the inside bottom of the hole with 3M Marine Adhesive 4200. Before it dried--I'm thinking this is where I make the mistake--I filled the hole with mash and actually laid whole fiberglass on top as I filled the entire hole. It was looking great and I'm thinking I'm almost finished when I notice smoke coming from the hole. So I panic, grab a screw driver and take out everything best I can. The material was hot and looked like I installed too much fiber. [Next,] I cleaned the hole, tried just 105 and 206, again with mesh a fiber whole pieces, but I [did not] fill that much. Same [result] is happening. [There is] heat and I are afraid it's going to create a fire. Tell me what I'm doing wrong. Thanks, cheepskater.
contender	posted 05-01-2010 07:50 PM ET (US) [Advice about hardener ratios deleted--jimh] Clean out the 3m4200 redrill the hole to clean it out and remove all the loose material. Use a product like superbond epoxy adhesive. It's a mix that is 50/50. It will look like a thick off-yellow paste. You need to find yourself a large syringe or a tool of this nature, mix the epoxy, place it in the syringe, and squirt it in the hole. Using a syringe; you can force the epoxy in all the way in the hole and you can do this from both sides to fill it properly. At the same time force all the air out of the void. I would use some type of tape, or, if you can, set something up to block the hole on the hull side to prevent the epoxy from running out. Figure this out before you mix and shoot the epoxy in the hole. Good luck
jimh	posted 05-01-2010 10:20 PM ET (US) The chemical reaction between epoxy resin and its hardener is an exothermic reaction. The greater volume of reagents used, the more heat is produced. If you mix up a large volume of pure epoxy and pour or inject it into a void, you can create a lot of heat as the reaction takes place. The rate of reaction increases with heat, so as the reaction warms the reagents, the reaction rate increases, producing more heat, which in turn increases the reaction rate, making more heat. As you discovered, the reagents can get very hot. Enough heat can be produced to melt foam and other plastics. You should use epoxy resin as an adhesive, not as a filler. Mix the resin with a filler material. Fill the void in the hull in stages, not all at once.
Jerry Townsend	posted 05-02-2010 01:19 AM ET (US) [Gave a reply that assumed a polyester resin was used with a catalyst hardener. This was not the case.--jimh]
jimh	posted 05-02-2010 08:53 AM ET (US) To contender and Jerry'--The resin used was specified as WEST System epoxy, not polyester resin. The ratio of resin to hardener in WEST System epoxy is not a matter of a few drops, but is more like 3:1. Any large concentration of curing epoxy will generate substantial heat. You do not need to fill the entire volume of the bow eye hole with new material. Just built up the hole until its diameter is smaller than the bow eye threaded rod. If there is a large void at either end of the hole, build up this area with epoxy resin thickened with filler material in stages. If you pour a cup of curing epoxy down the hole, it will generate too much heat.
contender	posted 05-02-2010 11:11 AM ET (US) Jim:.. I found this under West System Epoxy...[Long cut and paste without attribution deleted.]
jimh	posted 05-02-2010 11:38 AM ET (US) The curing of epoxy is a chemical reaction. The speed of the reaction is not influenced by the amount of either reagent being in excess of the stoichiometric ratio. The speed of reaction is influenced by temperature.
jimh	posted 05-02-2010 05:20 PM ET (US) WEST System epoxy is not cured by a catalyst. The two reagents of the reaction are mixed in their stoichiometric proportions and turn into a new compound. The reagents should always be mixed in the proper proportions. An excess of either reagent just produces a diluted epoxy which will not be as strong or cure as well. This is why WEST System sells mixing pumps and pre-sized mix packages. The heat that was created was not due to using too much hardener. You simply had too much epoxy concentrated in a small area.
cheepskater	posted 05-02-2010 06:44 PM ET (US) Thanks alot for your help everyone. Today I tried again and used the premixed WEST epoxy and hardened and only put small amounts at once and basically have been doing small amounts at a time. Thanks for the assistance it helped a ton.
dfmcintyre	posted 05-03-2010 08:56 AM ET (US) Another way to do that type of repair (deep hole) and avoid excessive exotherming, is to use the West epoxy that's slow reacting. The extra slow hardener is 209. Regards - Don