Home |
Search |
Today's Posts |
#1
posted to rec.boats.building
|
|||
|
|||
Serious epoxy problems
My three yr old Tolman 20' Standard Skiff has some serious epoxy
problems that cause me to doubt that this building method can work for my N. FL conditions. I built her with System 3 resin using the slow hardener due to the heat here. I used the metering pumps o get correct ratios and followed the builders directions. All went well for the first two years but then got a separation of epoxied wood at the transom. This had been glued by first painting the wood with epoxy followed by a thin layer of epoxy/fiber paste and serious clamping. I pried the two layers apart last year and re- filled with epoxy thinking the problem solved (NOT). Yesterday, I found the biax separating from the stringers, a long piece that had been clamped to the gunwales and glued separating and other places where the epoxy simply had not adhered to the wood. I will be able to use her for the next couple weeks (scallop season) but this will require some major surgery. Under N. FL humidity and rain, it is nearly impossible to keep her dry and I suspect that swelling of the wood due to absorption of water is the big problem. I plan to remove all the rest of the expensive paint i put over the original epoxy primer because it simply did not adhere anyway. Then will grind out the bad areas dry everything and try to re-glass the bad areas after using a heat gun to dry them. I would hesitate to use epoxy/glass over wood for another project here in N. FL conditions. |
#2
posted to rec.boats.building
|
|||
|
|||
Serious epoxy problems
Frogwatch wrote:
My three yr old Tolman 20' Standard Skiff has some serious epoxy problems that cause me to doubt that this building method can work for my N. FL conditions. I built her with System 3 resin using the slow hardener due to the heat here. I used the metering pumps o get correct ratios and followed the builders directions. All went well for the first two years but then got a separation of epoxied wood at the transom. This had been glued by first painting the wood with epoxy followed by a thin layer of epoxy/fiber paste and serious clamping. I pried the two layers apart last year and re- filled with epoxy thinking the problem solved (NOT). Yesterday, I found the biax separating from the stringers, a long piece that had been clamped to the gunwales and glued separating and other places where the epoxy simply had not adhered to the wood. I will be able to use her for the next couple weeks (scallop season) but this will require some major surgery. Under N. FL humidity and rain, it is nearly impossible to keep her dry and I suspect that swelling of the wood due to absorption of water is the big problem. I plan to remove all the rest of the expensive paint i put over the original epoxy primer because it simply did not adhere anyway. Then will grind out the bad areas dry everything and try to re-glass the bad areas after using a heat gun to dry them. I would hesitate to use epoxy/glass over wood for another project here in N. FL conditions. doesn't sound right to me. Note that wood expands and contracts with moisture - epoxy and other things with temperature. Might also be an amine blush issue between the different coats of epoxy. Also, most epoxies are brittle and cannot handle movement without the reinforcement of fiberglass cloth. There are flexible epoxies to use when painting... Epoxy primer is just solvent thinned epoxy. If you covered your hull with epoxy during building then it was already primed. If you used a 2 part LPU coating you certainly needed an epoxy primer, but your epoxy blushed, that would explain a few things. Email me privately and I will get you a sample of our Basic No Blush epoxy for you to evaulate. So what did the MAS epoxy folks say????? paul oman progressive epoxy polymers inc www.epoxyproducts.com/marine.html |
#3
posted to rec.boats.building
|
|||
|
|||
Serious epoxy problems
On Jul 27, 7:01*pm, Paul Oman wrote:
Frogwatch wrote: My three yr old Tolman 20' Standard Skiff has some serious epoxy problems that cause me to doubt that this building method can work for my N. FL conditions. I built her with System 3 resin using the slow hardener due to the heat here. *I used the metering pumps o get correct ratios and followed the builders directions. All went well *for the first two years but then got a separation of epoxied wood at the transom. *This had been glued by first painting the wood with epoxy followed by a thin layer of epoxy/fiber paste and serious clamping. *I pried the two layers apart last year and re- filled with epoxy thinking the problem solved (NOT). Yesterday, I found the biax separating from the stringers, a long piece that had been clamped to the gunwales and glued separating and other places where the epoxy simply had not adhered to the wood. *I will be able to use her for the next couple weeks (scallop season) but this will require some major surgery. Under N. FL humidity and rain, it is nearly impossible to keep her dry and I suspect that swelling of the wood due to absorption of water is the big problem. I plan to remove all the rest of the expensive paint i put over the original epoxy primer because it simply did not adhere anyway. *Then will grind out the bad areas dry everything and try to re-glass the bad areas after using a heat gun to dry them. I would hesitate to use epoxy/glass over wood for another project here in N. FL conditions. doesn't sound right to me. Note that wood expands and contracts with * moisture - epoxy and other things with temperature. Might also be an amine blush issue *between the different coats of epoxy. Also, most epoxies are brittle and cannot handle movement without the reinforcement of fiberglass cloth. There are flexible epoxies to use when painting... Epoxy primer is just solvent thinned epoxy. If you covered your hull with epoxy during building then it was already primed. If you used a 2 part LPU coating you certainly needed an epoxy primer, but your epoxy blushed, that would explain a few things. Email me privately and I will get you a sample of our Basic No Blush epoxy for you to evaulate. So what did the MAS epoxy folks say????? paul oman progressive epoxy polymers incwww.epoxyproducts.com/marine.html This is worse. The biax glass actually cracked over the stringers and the 8 oz glass cracked over the gunwales. These are not high stress areas but the stringers where it cracked does have a 1" radius of curvature. Note, these cracks and delams are in areas covered by glass. These are not normal use stress cracks but the epoxy separating from the wood and the glass actually cracking afterward. The epoxy primer is a 2 part material thinned with Isopropyle alchohol to protect the epoxy from UV. It works well and I will use it as my finish coat from now on. All of the areas appear to be areas where the epoxy simply did not adhere to the wood well allowing the epoxied glass to flex and crack. My issue now is how to fix the delams. Do I simply inject epoxy and drive screws to hold them till it sets or do I leave said screws in place. I worry future epoxy by itself will also fail. In areas where the layers of biax separated from the stringers, do I somehow make the biax layers adhere to said stringers or do I grind away the old biax and replace it with fresh stuff. |
#4
posted to rec.boats.building
|
|||
|
|||
Serious epoxy problems
Frogwatch wrote:
On Jul 27, 7:01 pm, Paul Oman wrote: Frogwatch wrote: My three yr old Tolman 20' Standard Skiff has some serious epoxy problems that cause me to doubt that this building method can work for my N. FL conditions. I built her with System 3 resin using the slow hardener due to the heat here. I used the metering pumps o get correct ratios and followed the builders directions. All went well for the first two years but then got a separation of epoxied wood at the transom. This had been glued by first painting the wood with epoxy followed by a thin layer of epoxy/fiber paste and serious clamping. I pried the two layers apart last year and re- filled with epoxy thinking the problem solved (NOT). Yesterday, I found the biax separating from the stringers, a long piece that had been clamped to the gunwales and glued separating and other places where the epoxy simply had not adhered to the wood. I will be able to use her for the next couple weeks (scallop season) but this will require some major surgery. Under N. FL humidity and rain, it is nearly impossible to keep her dry and I suspect that swelling of the wood due to absorption of water is the big problem. I plan to remove all the rest of the expensive paint i put over the original epoxy primer because it simply did not adhere anyway. Then will grind out the bad areas dry everything and try to re-glass the bad areas after using a heat gun to dry them. I would hesitate to use epoxy/glass over wood for another project here in N. FL conditions. doesn't sound right to me. Note that wood expands and contracts with moisture - epoxy and other things with temperature. Might also be an amine blush issue between the different coats of epoxy. Also, most epoxies are brittle and cannot handle movement without the reinforcement of fiberglass cloth. There are flexible epoxies to use when painting... Epoxy primer is just solvent thinned epoxy. If you covered your hull with epoxy during building then it was already primed. If you used a 2 part LPU coating you certainly needed an epoxy primer, but your epoxy blushed, that would explain a few things. Email me privately and I will get you a sample of our Basic No Blush epoxy for you to evaulate. So what did the MAS epoxy folks say????? paul oman progressive epoxy polymers incwww.epoxyproducts.com/marine.html This is worse. The biax glass actually cracked over the stringers and the 8 oz glass cracked over the gunwales. These are not high stress areas but the stringers where it cracked does have a 1" radius of curvature. Note, these cracks and delams are in areas covered by glass. These are not normal use stress cracks but the epoxy separating from the wood and the glass actually cracking afterward. The epoxy primer is a 2 part material thinned with Isopropyle alchohol to protect the epoxy from UV. It works well and I will use it as my finish coat from now on. All of the areas appear to be areas where the epoxy simply did not adhere to the wood well allowing the epoxied glass to flex and crack. My issue now is how to fix the delams. Do I simply inject epoxy and drive screws to hold them till it sets or do I leave said screws in place. I worry future epoxy by itself will also fail. In areas where the layers of biax separated from the stringers, do I somehow make the biax layers adhere to said stringers or do I grind away the old biax and replace it with fresh stuff. I would grind off anything not bonding and redo with fresh glass. Epoxy is strictly a surface bond so if you had lots of sanding dust, etc. on the surface that would impact the bonding. Adding/thinning with Iso alcohol does nothing to address the UV issue. You cannot add uv blockers to thermoset resin systems like epoxy. Thinning/solvent adding to epoxy will mess up the epoxy properties. If applied too thick you get solvent entrapment in the epoxy making it sort of rubbery. Best is probably a thin coat of solvent thinned epoxy on the raw wood then 'straight' epoxy with the glassing. Then enamel or water based paint on top... paul oman/progressive epoxy |
#5
posted to rec.boats.building
|
|||
|
|||
Serious epoxy problems
"Frogwatch" wrote: The epoxy primer is a 2 part material thinned with Isopropyle alchohol to protect the epoxy from UV. Wrong alcohol. you need denatured not isopropyl which contains water. You also must limit alcohol to less than 5%. As far as the glass is concerned, 8 OZ is little more than sealing tape. At a minimum, you need a couple of layers of 17 OZ, double bias glass. Leaving wood unglassed is asking for trouble which you seem to have found. Time to break out your right angle sander/grinder with some 24 grit and take everything back to bare wood, then reglass making sure you seal all wood with glass. If that is more work than it's worth, probably time for a new boat. Have fun. Lew |
#6
posted to rec.boats.building
|
|||
|
|||
Serious epoxy problems
On Jul 28, 7:22*pm, "Lew Hodgett" wrote:
"Frogwatch" wrote: The epoxy primer is a 2 part material thinned with Isopropyle alchohol to protect the epoxy from UV. Wrong alcohol. you need denatured not isopropyl which contains water. You also must limit alcohol to less than 5%. As far as the glass is concerned, 8 OZ is little more than sealing tape. At a minimum, you need a couple of layers of 17 OZ, double bias glass. Leaving wood unglassed is asking for trouble which you seem to have found. Time to break out your right angle sander/grinder with some 24 grit and take everything back to bare wood, then reglass making sure you seal all wood with glass. If that is more work than it's worth, probably time for a new boat. Have fun. Lew Never take advice from people who do not read. |
#7
posted to rec.boats.building
|
|||
|
|||
Serious epoxy problems
Frogwatch wrote:
On Jul 27, 7:01 pm, Paul Oman wrote: Frogwatch wrote: My three yr old Tolman 20' Standard Skiff has some serious epoxy problems that cause me to doubt that this building method can work for my N. FL conditions. I built her with System 3 resin using the slow hardener due to the heat here. I used the metering pumps o get correct ratios and followed the builders directions. All went well for the first two years but then got a separation of epoxied wood at the transom. This had been glued by first painting the wood with epoxy followed by a thin layer of epoxy/fiber paste and serious clamping. I pried the two layers apart last year and re- filled with epoxy thinking the problem solved (NOT). Yesterday, I found the biax separating from the stringers, a long piece that had been clamped to the gunwales and glued separating and other places where the epoxy simply had not adhered to the wood. I will be able to use her for the next couple weeks (scallop season) but this will require some major surgery. Under N. FL humidity and rain, it is nearly impossible to keep her dry and I suspect that swelling of the wood due to absorption of water is the big problem. I plan to remove all the rest of the expensive paint i put over the original epoxy primer because it simply did not adhere anyway. Then will grind out the bad areas dry everything and try to re-glass the bad areas after using a heat gun to dry them. I would hesitate to use epoxy/glass over wood for another project here in N. FL conditions. doesn't sound right to me. Note that wood expands and contracts with moisture - epoxy and other things with temperature. Might also be an amine blush issue between the different coats of epoxy. Also, most epoxies are brittle and cannot handle movement without the reinforcement of fiberglass cloth. There are flexible epoxies to use when painting... Epoxy primer is just solvent thinned epoxy. If you covered your hull with epoxy during building then it was already primed. If you used a 2 part LPU coating you certainly needed an epoxy primer, but your epoxy blushed, that would explain a few things. Email me privately and I will get you a sample of our Basic No Blush epoxy for you to evaulate. So what did the MAS epoxy folks say????? paul oman progressive epoxy polymers incwww.epoxyproducts.com/marine.html This is worse. The biax glass actually cracked over the stringers and the 8 oz glass cracked over the gunwales. These are not high stress areas but the stringers where it cracked does have a 1" radius of curvature. Note, these cracks and delams are in areas covered by glass. These are not normal use stress cracks but the epoxy separating from the wood and the glass actually cracking afterward. The epoxy primer is a 2 part material thinned with Isopropyle alchohol to protect the epoxy from UV. It works well and I will use it as my finish coat from now on. All of the areas appear to be areas where the epoxy simply did not adhere to the wood well allowing the epoxied glass to flex and crack. My issue now is how to fix the delams. Do I simply inject epoxy and drive screws to hold them till it sets or do I leave said screws in place. I worry future epoxy by itself will also fail. In areas where the layers of biax separated from the stringers, do I somehow make the biax layers adhere to said stringers or do I grind away the old biax and replace it with fresh stuff. It just sounds like you didn't prepare the wood properly. I use a sawblade turned on it's side and scrape negative gashes into the wood to produce a more mechanical bond than chemical. Also, you may have had other problems with the laminating process, sometimes with Epoxy, more is not necessarily better.. |
#8
posted to rec.boats.building
|
|||
|
|||
Serious epoxy problems
On Jul 30, 9:21*pm, "Just wait a frekin' minute!"
wrote: Frogwatch wrote: On Jul 27, 7:01 pm, Paul Oman wrote: Frogwatch wrote: My three yr old Tolman 20' Standard Skiff has some serious epoxy problems that cause me to doubt that this building method can work for my N. FL conditions. I built her with System 3 resin using the slow hardener due to the heat here. *I used the metering pumps o get correct ratios and followed the builders directions. All went well *for the first two years but then got a separation of epoxied wood at the transom. *This had been glued by first painting the wood with epoxy followed by a thin layer of epoxy/fiber paste and serious clamping. *I pried the two layers apart last year and re- filled with epoxy thinking the problem solved (NOT). Yesterday, I found the biax separating from the stringers, a long piece that had been clamped to the gunwales and glued separating and other places where the epoxy simply had not adhered to the wood. *I will be able to use her for the next couple weeks (scallop season) but this will require some major surgery. Under N. FL humidity and rain, it is nearly impossible to keep her dry and I suspect that swelling of the wood due to absorption of water is the big problem. I plan to remove all the rest of the expensive paint i put over the original epoxy primer because it simply did not adhere anyway. *Then will grind out the bad areas dry everything and try to re-glass the bad areas after using a heat gun to dry them. I would hesitate to use epoxy/glass over wood for another project here in N. FL conditions. doesn't sound right to me. Note that wood expands and contracts with * moisture - epoxy and other things with temperature. Might also be an amine blush issue *between the different coats of epoxy. Also, most epoxies are brittle and cannot handle movement without the reinforcement of fiberglass cloth. There are flexible epoxies to use when painting... Epoxy primer is just solvent thinned epoxy. If you covered your hull with epoxy during building then it was already primed. If you used a 2 part LPU coating you certainly needed an epoxy primer, but your epoxy blushed, that would explain a few things. Email me privately and I will get you a sample of our Basic No Blush epoxy for you to evaulate. So what did the MAS epoxy folks say????? paul oman progressive epoxy polymers incwww.epoxyproducts.com/marine.html This is worse. *The biax glass actually cracked over the stringers and the 8 oz glass cracked over the gunwales. *These are not high stress areas but the stringers where it cracked does have a 1" radius of curvature. *Note, these cracks and delams are in areas covered by glass. *These are not normal use stress cracks but the epoxy separating from the wood and the glass actually cracking afterward. The epoxy primer is a 2 part material thinned with Isopropyle alchohol to protect the epoxy from UV. *It works well and I will use it as my finish coat from now on. All of the areas appear to be areas where the epoxy simply did not adhere to the wood well allowing the epoxied glass to flex and crack. My issue now is how to fix the delams. *Do I simply inject epoxy and drive screws to hold them till it sets or do I leave said screws in place. *I worry future epoxy by itself will also fail. In areas where the layers of biax separated from the stringers, do I somehow make the biax layers adhere to said stringers or do I grind away the old biax and replace it with fresh stuff. It just sounds like you didn't prepare the wood properly. I use a sawblade turned on it's side and scrape negative gashes into the wood to produce a more mechanical bond than chemical. Also, you may have had other problems with the laminating process, sometimes with Epoxy, more is not necessarily better.. I intend to something similar when I re-glass the bad areas. |
#10
posted to rec.boats.building
|
|||
|
|||
Serious epoxy problems
"JustWait" wrote in message ... In article 434f169d-b755-48a0-91f5- , says... My three yr old Tolman 20' Standard Skiff has some serious epoxy problems that cause me to doubt that this building method can work for my N. FL conditions. I built her with System 3 resin using the slow hardener due to the heat here. I used the metering pumps o get correct ratios and followed the builders directions. All went well for the first two years but then got a separation of epoxied wood at the transom. This had been glued by first painting the wood with epoxy followed by a thin layer of epoxy/fiber paste and serious clamping. I pried the two layers apart last year and re- filled with epoxy thinking the problem solved (NOT). Yesterday, I found the biax separating from the stringers, a long piece that had been clamped to the gunwales and glued separating and other places where the epoxy simply had not adhered to the wood. I will be able to use her for the next couple weeks (scallop season) but this will require some major surgery. Under N. FL humidity and rain, it is nearly impossible to keep her dry and I suspect that swelling of the wood due to absorption of water is the big problem. I plan to remove all the rest of the expensive paint i put over the original epoxy primer because it simply did not adhere anyway. Then will grind out the bad areas dry everything and try to re-glass the bad areas after using a heat gun to dry them. I would hesitate to use epoxy/glass over wood for another project here in N. FL conditions. Hey Froggie, Scotty here from that other group I think I remember back when you were doing this, did you encapsulate the wood in Epoxy? I have always been against that, moisture gets in, but can't get out. I suggest regular paint as a sealer, just for the record... FWIW, Paul Oman nailed the major issues that look like a possible failure route here. First, how long did you wait between painting on the original coat of epoxy and applying the paste? If it was too long, amine blush is a possible culprit. Depending on the mix, 12 - 15 hours can be too long. 24 hours is more likely the max. After that, you have to remove the amine blush with soap and water, and you will get NO chemical bond, in any case. You'll have to roughen the surface of the prime layer and depend on the mechanical bond. Second, "serious clamping" can be a mistake with epoxy. If it's squeezed out to a layer thinner than roughly 0.003", strength falls off quickly. Below 0.002", it can all but disappear. Unlike resorcinol or some other adhesives, you shouldn't clamp epoxy more than it takes to hold everything in place. That applies especially to amine-cure epoxies. Clamping wood more than a minimum will leave some percentage of the bonded area with a too-thin layer, which can be a starting point for peel or cleavage failure. As Paul also said, brittleness and low peel strength of most epoxies, combined with swelling and shrinking of the wood, can lead to failure. Peel strength usually isn't much of an issue when epoxy is used to bond wood, but it's an inherent weakness of the adhesive -- again, especially with amine-cure epoxies. It's most likely to show up at place where end grain is exposed. Slowing down the absorption rate by coating with epoxy and fabric is the best solution for that, because it will allow the creep rate of the epoxy to partially catch up to the wood expansion, but it's not perfect. -- Ed Huntress |
Reply |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
old epoxy | Boat Building | |||
how much epoxy | Boat Building | |||
Epoxy fibreglass on top of epoxy primer | Boat Building | |||
Old epoxy--somewhat OT (but it's an epoxy question) | Boat Building | |||
epoxy | Boat Building |