Bondo on epoxy?

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Bondo on epoxy?

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fgayford	fgayford posted 9 Years Ago HOT Post Details
Group: Forum Members Posts: 433, Visits: 1.2K	Hanaldo (05/04/2016) f1rob (31/03/2016) A polyester will stick to an epoxy a lot better than a epoxy will stick to a polyester even thou the epoxy is stronger Never had any problems but surface prep is important Not to hijack the thread too much, but you've brought this up at an interesting time for me Rob. I have been discussing the issue of epoxy/polyester bonds with some friends in the gliding scene, one of whom used to make fibreglass boats for a living. For reasons I can not fathom, he absolutely swears by polyester resin. He considers it the be all and end all of composite resins, and refuses to work with epoxy. One of the reasons he gave for polyester being better is that it will bond to epoxy, but epoxy won't bond to polyester. Something that makes absolutely no sense to me, considering polyester is extremely poor at bonding to anything including itself; whilst epoxy is one of the most widely used adhesives around - because it's bloody good at sticking to things. Now I tried to do a quick bit of research on this topic, but literally EVERYTHING I come across backs up my belief that epoxy bonds to polyester better than the other way around. So I'd love to hear your thoughts on that? Keying the surface and wiping with solvent will allow either resin to bond or glue the parts together. Think of gluing two sponges together with either resin. The resin will migrate into every pore and you will have a mechanical bond that is only as strong as the cured resin. Epoxy I believe has more tensile strength than polyester so would be stronger. Your boat builder probably likes polyester better because for days after the cure you can apply more resin cloth layers and it will co cure and crosslink with the surface because the surface layer is not cured. (air prevents this unless you add a chemical) This next layer doesn't bond it crosslinks making it as one. Now epoxy will not do this if you leave it overnight. You can only make a mechanical bond to its surface. But if you allow an epoxy part to cure to only a tack free state you can add another layer and it will crosslink and make it as one. This window of time with epoxy is very short and harder to hit than polyester. Two Cents. Fred
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f1rob	f1rob posted 9 Years Ago HOT Post Details
Group: Forum Members Posts: 237, Visits: 4.8K	What car is it for ???
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Hanaldo	Hanaldo posted 9 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	The Lotus stuff I've worked with I would swear they haven't used any moulds. Or any form of consolidation. They are so full of bog and voids, even my panel beater is ashamed of them!
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f1rob	f1rob posted 9 Years Ago HOT Post Details
Group: Forum Members Posts: 237, Visits: 4.8K	One of my proud boasts is to say I have never worked for lotus cars ! some of the bodies done with VARI are a bit dodgy to say the least ! But they are better than the new stuff done by sater for Lotus,that is more plaster Than resin and is breaking before they get to the paint shop. Team Lotus was always "hectic" to say the least but cars would normally be back by a Monday lunchtime so we normally had a week do do the turn around so not too rushed funny thing epoxies have improved but today on the rare occasions people do repairs in F1 most people choose to use 3M 9392 rather than normal resin
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Hanaldo	Hanaldo posted 9 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	If they were with Lotus then I don't believe a word they said, their panels are the worst I've worked on! That is interesting though, in all seriousness. Would that not just be for speed of the repair?
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f1rob	f1rob posted 9 Years Ago HOT Post Details
Group: Forum Members Posts: 237, Visits: 4.8K	When I first got into this game 82/83 ish pre preg had only been out (or I should say in use in f1) for a couple of years there was a split between pre preg (floors,rear flips ect) wet lay epoxy vac (endplates,elements ect) and polyester hand lay glass (brake ducts,bodywork ect) ALL repairs were polyester and the guys who were there had been with lotus cars/moonraker marine/jcl from early 60,s an that's what I was told never saw any repairs delam
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Hanaldo	Hanaldo posted 9 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	f1rob (31/03/2016) A polyester will stick to an epoxy a lot better than a epoxy will stick to a polyester even thou the epoxy is stronger Never had any problems but surface prep is important Not to hijack the thread too much, but you've brought this up at an interesting time for me Rob. I have been discussing the issue of epoxy/polyester bonds with some friends in the gliding scene, one of whom used to make fibreglass boats for a living. For reasons I can not fathom, he absolutely swears by polyester resin. He considers it the be all and end all of composite resins, and refuses to work with epoxy. One of the reasons he gave for polyester being better is that it will bond to epoxy, but epoxy won't bond to polyester. Something that makes absolutely no sense to me, considering polyester is extremely poor at bonding to anything including itself; whilst epoxy is one of the most widely used adhesives around - because it's bloody good at sticking to things. Now I tried to do a quick bit of research on this topic, but literally EVERYTHING I come across backs up my belief that epoxy bonds to polyester better than the other way around. So I'd love to hear your thoughts on that?
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67redrocket	67redrocket posted 9 Years Ago HOT Post Details
Group: Forum Members Posts: 49, Visits: 486	Hanaldo (31/03/2016) Bondo is just a brand (the original brand I believe) of polyester body filler. I did not know that, i thought Bondo was another name for body filler. Not always easy to transfer from norwegian Thank you all for feedback
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kidpaint	kidpaint posted 9 Years Ago HOT Post Details
Group: Forum Members Posts: 99, Visits: 676	youll be fine. Ive often had to fix little spots after I have sanded the primer and the guide coat showed the low spot. Make sure the primer is rough sanded so it has a bite for the filler to stick to Edited 9 Years Ago by kidpaint
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f1rob	f1rob posted 9 Years Ago HOT Post Details
Group: Forum Members Posts: 237, Visits: 4.8K	A polyester will stick to an epoxy a lot better than a epoxy will stick to a polyester even thou the epoxy is stronger Never had any problems but surface prep is important
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