Oops Not Enough Hardner?

memberG405

New Member
Hey guys, quick question I had finished a pep helmet and went to resin the outside with FB but (according to the video - one lid + 8 drops) didnt harden fully. There were still gooey spots all over the helmet. Either i didn't mix it thoroughly, or I didn't use enough hardener. What can I do now? Can I re-resin it? Do i have to start over?
 

Roadwarrior

Well-Known Member
FB? fiberglass bondo?



Well the "Bondo all purpose fiberglass resin" lid is 4oz's and it's 8 drops an oz, it's on the container. I suggest reading the instructions on you're product.
 

ka5p3r

Well-Known Member
yea with the lid from the can i use like 32 drops for fast drying. but you can add another layer of resign on top that one to get the rest to harden up fully
 

memberG405

New Member
Roadwarrior said:
FB? fiberglass bondo?



Well the "Bondo all purpose fiberglass resin" lid is 4oz's and it's 8 drops an oz, it's on the container. I suggest reading the instructions on you're product.




I am sorry Let me clarify it was just the fiberglass resin, i haven't gotten to the bondo yet.



Will baby powder work for resin or bondo?
 
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Kodorei

Member
Memberg said:
I am sorry Let me clarify it was just the fiberglass resin, i haven't gotten to the bondo yet.



Will baby powder work for resin or bondo?
It will make it less tacky yeah...

But add another layer to make it stronger and so that it cures properly.
 
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Cadet

Executive Officer & RCO
Division Staff
405th Regiment Officer
Hit it with another layer of resin, or hit it with a heat gun/hair dryer. That will sort of melt the resin slightly back into liquid state, and have it reharden, the heat will also help to catalyze the hardening process.
 

NAGA

Jr Member
I had this problem with one of my thigh pieces. It took 2 days for it to finally dry up. Like it was suggested, you can put another coat of resin on it, but waiting it out should work, too.
 

Blackwatch

New Member
I am glad I found this. I have worked with plenty of epoxies but never with fiberglass resin so this in particular has worried me. I work with a lot of props and models that are made entirely from FG resin and I run into the situation where the resin has not cured all the time.



Intersting bit of information about the baby powder and reheating to catalyze. In the past I have always gouged out an area and repacked it with epoxy putty, but that is certainly worth a shot.
 

Liq

Well-Known Member
Is it sitting outside drying in cooler weather? I was having a tough time getting my last few pep pieces to dry as quick as I needed them in late Sept and early November even in Alabama. Like others have said though, go to it with a hairdryer and baby powder. I've done both and it works fine.
 

insanetrooper

Jr Member
hey, same thing happened to my whole forarm part.

mix up some more resin and add a couple more drops than you normaly would

and brush it over the sticky spots and it will dry very nice :D
 

BFDesigns

Well-Known Member
I've used many methods for not enough hardener, especially when cooler weather hits. But the hairdryer method works really well, and also applying a few drops of the hardener (2 or 3) directly to the area that feels tacky and rubbing them all around the affected area with a gloved hand also works really well, and doubling up on the hardener when it gets cold outside also helps to get a good curing.



Creating a microclimate works well too which you can do by either building a wooden box and cutting holes for spot lamps with heat bulbs (pet store) and leaving your part in the box for about 10-20 minutes, or by setting your oven to 120°F and throwing your part in for about 10 minutes (use this method at your own risk as the health risks of cooking in an oven that you use to cure resin in are unknown, and it makes the kitchen and most of the house smell like resin; just because I've done it doesn't mean that you should!).



Another way if you have an electric stove or a portable electric element is to turn it on to high heat and hold the sticky part 4-6 inches over the red hot element, it will very quickly raise the temperature of the uncured area to curing temperatures. Be careful with this method as you need the part to reach 120°F (hot to the touch) but any higher and you risk fire, burns, or part warping. The part may discolor when using this method, it doesn't seem to affect the overall strength of the part tho so try not to freak out if the resin turns brown, just get it away from the element and let it cool. When it cools it should be cured.



The thing behind polyester resin, bondo, and even a lot of smoothcast resins and some silicones is that they are thermosetting. That means that they need some type of heat to polymerize and become rigid. The hardener you add (methyl ethyl ketone peroxide [MEKP] in the case of bondo and polyester resin) creates an exothermic (heat producing) reaction when combined with the monomeric resin in the right proportions, which is why resin and bondo get hot while they cure. Adding too little to the resin or leaving the part in a cool or cold place to cure results in not enough heat to polymerize the resin quickly so the trick is to somehow add heat to aid the hardener in the creation of the polymer chains.
 

memberG405

New Member
Liq said:
Is it sitting outside drying in cooler weather? I was having a tough time getting my last few pep pieces to dry as quick as I needed them in late Sept and early November even in Alabama. Like others have said though, go to it with a hairdryer and baby powder. I've done both and it works fine.


No I live in Arizona and its been about 65 Degrees 70+ in the sun.
 
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lgeek

New Member
About 2 years ago I did a fiberglass project but didn't put near enough hardener in the mix. Maybe 1/10th of what it should have been. It was sticky after a week so I sanded the surface and was going to redo it, but ended up setting it aside. For months it smelled. I just started thinking about it this week and found that the smell was completely gone. It appears to have fixed the broken surface, but I haven't stressed it. Is it possible the fiberglass took two years to set and it is okay now?
 

Sean Anwalt

RCO
405th Regiment Officer
Hey @Igeek, this thread is more than a decade old, man. Please try not to respond to threads older than ~6 months. It pushes active threads down.

To answer your question, it's possible after teo years the stuff has set, sure, but what I would do is give it another quick coat of resin, let it cure, then sand it gently before moving to the bondo stage.

Welcome aboard! You should start a thread to show your progress!
 
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