Heating Epoxy resin in microwave (ding all)

Until recently I had only need of ding repair kits and never had issues with the resin curing hard/sandable.  Now I have a couple boards that need serious intervention so I got 24 oz of Ding all epoxy to see how it would hold up.  So far every batch has cured tacky and the company ghosted me for a return after having me try several more attempts.   I read here that microwaving the resin beforehand can help.  Just tried a pratice run in a plastic cup for 10 seconds after mixing. The air bubbles disappeared and it seems to be curing super fast.  Will know tomorrow morning if it’s finally a good cure.

Curious if anyone has tried this with ding all epoxy (I will never use again for a project, just don’t want to waste it), and whether it would also work with qcell or microspheres added.  I want to use the mixture over some pressure dings on a refurbished board, let dry, sand smooth, then paint.

Hi -

If they haven’t mentioned this already, you might try mixing both parts separately in their containers before carefully measuring out the specified proportions… it could matter if you’re mixing by weight or by volume.  Volume is usually 2:1, weight is a bit different. Whatever the formula is, stick to it.  I like to use a digital scale that weighs to the gram or less.

STIR WELL.

Make certain your temperature for the duration of the curing process is consistent with the specified temperatures in instructions… I.E. a cold night temperature might affect the cure even if epoxy was applied at the correct temperature during day time hours.  A flash in a microwave might give the resin a bit of a short term boost but it does matter what happens over the following 24 hour (or more) period. 

If those techniques still result in a tacky batch, I’m afraid I’m stumped on this one.

Virtually every epoxy problem is operator error.  

I would tend to agree on operator error, but I’ve used ding all epoxy dozens and dozens of times with maybe one bad cure.  I’ve tried every trick from absolute precision in measurements to mixing separately to then transferring to a new cup.  Must be something to do with larger bottles than repair kits.  Ding all also doesn’t heat up like other epoxies (exothermic) as far as I can tell.

 

the microwaving has definitely produced a less tacky result than previous attempts with this batch.  Can still fingernail it but will see how it feels late afternoon and see if it’s sandable.

maybe it’s more temperature sensitive for some reason (upper 60s).  But previously I never encountered this even with quick mixing, humidity, etc.

 

Thank you John.  I’ve used the 2:1 ratio using these mini bottles like previous repair kits I’ve used.  One thing I didn’t try was mixing the Part A (viscous) bottle.   

 

I let the microwave batch cure at room temperature (70) overnight.  Says it can work as low as 60.  It started curing very fast after the zap for 9-10 seconds (first time I’ve ever felt ding all get hot).  Gave off odor when I took it out which isn’t good, but seemed to help.  This morning I could still scratch it a bit with stick, and also indent with fingernail with pressure, but it’s much harder than every previous attempt with this batch.  I’ll test sand this afternoon and report how this all goes.  

Only microwave the Part A Resin.  Do not microwave the Part B and do not microwave the two parts mixed.  Microwave the Part A Resin for a few seconds.  This will result in a more workable mix.  It has a thinning effect on the resin.  I micro the Part A a few seconds until warm or almost hot, but not smoking.  A few seconds is all it needs.  Not any hotter than coffee out of a coffee maker.  I never use those ding repair kits, so can’t give you an opinion.  I did ding repair on painted Epoxy boards using West Sysrem Epoxy and other “surfboard specific” resin such as Resin Research for a number of years with good results.

Thanks for the tip and I’ll try that next time.  I did suspect something was wrong with Part A.  Only 3 seconds? When I did 10 for a mixture it got warm but not crazy hot.

What goes wrong if you microwave it mixed and/or part B? I had read on another thread or site about someone doing both. I micro’d both together for a small test sample (probably too long at 9-10 seconds, it cured fast!), and then did it again for my actual 3 oz (2 A + 1 B) mix for 7-8 seconds.  I then added microspheres to smooth over an area of pre-sanded deck with lots of pressure dings (to be painted later).  It’s been 18 hours and it’s a much better cure than previous attempts using this finicky ding all batch. Still scratches but can’t indent with fingernail so I think it will sand away decently when I get to it.  

Following a method I watched someone else use to smooth a refurbished board for painting.  Picture below.  Some interesting lines formed after it settled.  Most of this will be sanded away I just wanted to cover the low spots.

 

Where there’s smoke, there’s fire.  Ruin your micro wave, blow up, start a fire, cure and turn to an unusable cup of crap.  Anything is possible.

Here is what I have been doing for years to warm up epoxy.  I made a “hot box” from a old cooler.I put a water proof seedling heat mat inside of it. Put part A in and plug it in.takes about a hour so plan ahead.ghetto ingenuity 

How about heating up water and placing part A inside? Same effect?  

 

And in terms of blowing up microwave (previous commment), I’d be wary of that as well but saw plenty of people say not to worry about it.  We’re talking 3-8 seconds nothing more.

Yeah the old hot water and bucket trick works,but make sure not to contaminate the epoxy with water drops when pouring/mixing

It is also possible that ‘post curing’ the epoxy might kick it off once and for all.  Some epoxies require you to do it but most that we would use on surfboards are at least theoretically room temperature cure types.  

That said, even room temperature cure type might benefit with a heating session - like in a closed up car, black plastic wrap, heating blanket or curing chamber.  I made a curing chamber out of rigid foam panels, plywood and some light bulb fixtures that worked for epoxy even in the dead of winter glassing outside.  You do need to be careful with pin air and delams… I.E. not too hot.  Once it’s well past the green state you can crank it a bit. 

Post curing also reduces epoxy softening and delams in the hot sun later on.  I don’t have a specific formula on that but a high temp post cure will definitely result in epoxy staying harder in hotter temperatures if your board gets hot. 

Many industrial applications demand the post curing so this idea isn’t hogwash.  EPS foam melting point might be the limiting factor…

My thought on the hot water would be leaving the container of resin in hot water for a time, then drying it to remove any water droplets before pouring.  

 

The comment about post cure temps is interesting. I hadn’t considered that and couldn’t do much for this microwave batch that I applied, but will consider next time.  I haven’t sanded what I applied yet and might not get to until the spring.  But it was solid.

 

To wrap up for anyone searching how to improve a finicky batch of epoxy resin (especially Ding All brand part a and b), microwaving the resin first definitely made a difference.  I went from a tacky mixture every single time with Ding All’s 8 oz containers, to normal hard cure I was used to using other kits.  

 

After reading comments and based on my experience, I would recommend microwaving Part A only for 3-8 seconds depending on how much you use.  Plastic container you poured it into should feel a bit warm after but don’t overdo it.  Then mix with part B (half part A amount for Ding All) and be prepared for a relatively quick kick in time.  I’m assuming the part A I was using needed the heat because it wasn’t properly mixed or had some other flaw that heat took care of.  Hard to mix part A well in their 8 oz containers.

 

thanks for all the advice and comments