Geno Posted October 22, 2018 Share Posted October 22, 2018 Hello all, I filled some seams etc, with a 2 part epoxy, my question is it's been 3 days and it's still not set up. I'm thinking I didn't get quite enough hardener mixed in it. Will this ever set up or am I going to have to tear the model apart and start over? Thanks for any and all help, Geno. Quote Link to comment Share on other sites More sharing options...
SfanGoch Posted October 23, 2018 Share Posted October 23, 2018 Are you using two-part epoxy dispensed from a syringe applicator? You need to get as close to a 1:1 ratio of resin and hardener as possible. The only way to do that is by placing the cap over the hole for each part and squeeze an equal amount of each separately. Don't try to be cheap with the amount of resin/hardener, either. There is always a significant amount of waste involved. attempting to use minute quantities will prevent the mixture to catalyze properly, leaving you with a gooey mess, as you have now. Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted October 23, 2018 Share Posted October 23, 2018 (edited) Joe is absolutely right if you're using the standard hardware-store applicator/mixer types, or the higher-grade hobby shop stuff. If it says mix 1:1, it is essential to get it as close to 1:1 as you can for it to work correctly. It's very difficult to get the exact mix if you're mixing VERY small amounts. Epoxy can be persnickety when trying to mix and use tiny amounts too, because it never generates sufficient exothermic heat to kick. Some gentle heat might help. Many epoxy products can't be used if the temps are below 60F. It also has a shelf-life; some of the stuff goes bad after 6 months and will never set up, no matter how well it's mixed. "Epoxy" is also a term that's misused a bunch, often interchangeably with polyester resin, which has entirely different chemistry and mixing ratios. What exactly are you using? Edited October 23, 2018 by Ace-Garageguy Quote Link to comment Share on other sites More sharing options...
BigTallDad Posted October 23, 2018 Share Posted October 23, 2018 How old is the epoxy you're using? That stuff does have a shelf life! Quote Link to comment Share on other sites More sharing options...
peteski Posted October 23, 2018 Share Posted October 23, 2018 Another possibility is that the epoxy and hardener were not mixed thoroughly enough. If you had a dehydrator (or some place where there is about 100 deg. F where you can place the model), you could try to put it there to see if the epoxy will set under elevated temperature. But from your description I doubt the epoxy will ever full set. 3 hours ago, Ace-Garageguy said: It also has a shelf-life; some of the stuff goes bad after 6 months and will never set up, no matter how well it's mixed. "Epoxy" is also a term that's misused a bunch, often interchangeably with polyester resin, which has entirely different chemistry and mixing ratios. What exactly are you using? Ace, I have never seen polyester resins used as model adhesive or filler, so I suspect that Gene was using some run-of-the-mill epoxy adhesive. Probably the 5-minute kind. But I agree that we need more detailed info from Gene to give him better advice. As far as mixing small quantities of the 1:1 ratio (like the 5-minute) epoxies go, they are not all that sensitive to keeping the exact ratio. I do not use the double-syringe type - I prefer the kind that comes in 2 individual aluminum "toothpaste" tubes with screw-on caps. I very often dispense a dollop each of epoxy and hardener onto a piece of masking tape stuck to a small palette, then using a toothpick I scoop up about a sunflower-seed-size of each and mix them thoroughly. I'm sure the ratio is not perfect, but I never have a problem with the epoxy not setting properly. Also, while I agree that it has a shelf life, I had some over 10 years old (Devcon brand 5-minute epoxy in individual tubes) and it worked just fine for me until I used it all up. Quote Link to comment Share on other sites More sharing options...
High octane Posted October 23, 2018 Share Posted October 23, 2018 I use the Devcon 5-Minute Epoxy and yes one needs to mix the amounts of both the resin and hardener as close to 1:1 you can or it probably won't set up and dry the way it should. As far as shelf life, if you don't open the packages and puncture the tubes, it should be good for a long time as I never have a problem with fresh packages of epoxy lying around for months. I've been using epoxy as my go-to glue for many years now and I like it because it has a strong bond and dries clear. I never have to take a "repair kit" when I bring my models to display at club meetings, NNL's, or shows as nothing falls off. Quote Link to comment Share on other sites More sharing options...
Geno Posted October 23, 2018 Author Share Posted October 23, 2018 Thanks guys for your input. It is the Loctite brand in 2 individual tubes less than a year old. I'm thinking I didn't get the mixture quite right but try to get it as 1:1 as possible. This is the first time I've had issues with it. What would be the best way to remove what's on there now to start over if I have too? Blessings, Geno. Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted October 23, 2018 Share Posted October 23, 2018 9 hours ago, peteski said: ...Ace, I have never seen polyester resins used as model adhesive or filler... Most of the "two part" fillers made for real car and hobby work are polyesters. Quote Link to comment Share on other sites More sharing options...
peteski Posted October 24, 2018 Share Posted October 24, 2018 16 hours ago, Ace-Garageguy said: Most of the "two part" fillers made for real car and hobby work are polyesters. Well, I was going by what was mentioned in the original question. But you are of correct about the body fillers for 1:1 cars (and often used by modelers). Either way, if the proportions were way off, the stuff will likely never fully cure. Quote Link to comment Share on other sites More sharing options...
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