Oh, by the way, the perfect ratio is 50% epoxy mix 50% microbaloons BY VOLUME NOT WEIGHT.
@ everysurfer
Laying cloth into a filler mix seems like a great idea. But so scary! I am sweating my non-existant balls off just trying to get the filler layer perfect before it sets up. LOL! Iām on my 3rd board. Maybe it goes faster with more experience. Do you use slower setting epoxy? I used Kwik Kick from Resin Research on the first side and almost had a heart attack in the summer heat. 
I use fiberglass Hawaii - fast. You only put enough micro/ epoxy slurry to fill the pockmarks in the eps. Wait until it has thickened, but still plastic and sticky. When you lay the cloth in it and squeegee the cloth with fresh epoxy, it all blends smooth. No sanding required. And again the mix is 50/50 epoxy/ microbaloons by volume. If you are good, you can go 60% microbaloons, but the more microbaloons you add, the less smooth it flows, but the lighter it gets.
Iāve got an even better trick coming. But I want to finish the build first so I have pictures.
Also, with this trick, you have a better chemical bond between layers. Thatās stronger than if you let the slurry cure.
Thanks Everysurfer,
I always struggled to get the filler mix right. So a cup of resin to a cup of microballoons?
Mix up your epoxy, 100 g. Epoxy and 40 g hardener for the stuff I use. Measures about an inch high in the mixing cup. Add an inch of microbaloons into the cup, and stir it all in. If spreadability is an issue, keep it there. If it is just ding filler, you can add another half inch. More than that and it looses its flow.
It depend of resin viscosity and microsphere density.
For clarity, Fiberglass Hawaii epoxy, Revchem microballoons.
I do this on all of mine, definitely donāt want to be using kwik kick on this process. It is also a way to get the glass to contour to channels and wings too. A bit of a warning, if you are planning on doing a colored lamination, the thickened epoxy will show b/c the glass is partially saturated in certain areas unless you squeegee really well. So go ahead and color that thickened epoxy and it becomes a functional and more controlled way to do resin art.
To the slurry fanatics, lots here know Iām one. Poly or epoxy, home or production.
Just practice. It gets easier and better each time. Donāt laminate too soonā¦let it gel properly.
and then you get lighter stronger boardsā¦
OK, maybe a dumb question. If you do a fill coat, wait for it to gel, then laminate immediately, when do you install the fins boxes? Cut through the glass??? Or before the fill layer? We have been doing a fill coat, install fin boxes (fusion fcs), then laminating. Yes I want a lighter and stronger board!!! It sounds scarey though, like I could also end up with a fuct up glass job because I am a beginner glasserā¦running around sweating and having a heart attack. LOL.
Hi SashaMelden, I think they were talking about that on this recent thread http://www.swaylocks.com/forums/sealing-eps-blank-under-glass-finboxes .
I would not worry about chaining steps together until you feel good about them, no sense stressing to save a few hours time.
Hi, sorry for reviving an olden, but the oldies are the best
I have a blank (old board with glass removed, and chunks of foam too). I donāt want to throw the board so I am planning on using Q Cell in resin to fill the rough bits before sanding carefully and glassing. I canāt seem to find info anywhere on how LONG it takes to cure. Does anyone know?
It takes as long as regular resin to cure. So, that means different things depending on how hot you mix the batch. Q cell is basically glass dust (someone correct me if Iām wrong), it wonāt effect cure time unless youāre using sun cure, then the q cell might hinder it from kicking.
Excellent thanks for that.
I am shooting over to a local surf supply store tomorrow, they sell this stuff http://www.seabase.eu/product/MFC/Seabase/Coatings-:AND:-Sealants/Ceramic-
Do you have similar stuff over there? If so, any idea how it would compare to q-cell? Ideally I am looking for the lightest possible end product to be as close to PU foam in weight as possible. Wondered if this stuff might be lighter than q-cell?
Iāve never heard of them, I wish somebody else would chime in. The word ābubblesā is interesting. Are they hollow inside, like regular bubbles? If so, I would stay away from those. Other than that, the only difference might be that they mix clear instead of white.
Iām of the understanding Qcell is hollow plastic spheres and microballoons are hollow glass spheres, but Iām open to an official technical description of the difference.
Density wise, in bulk, microballons felt heavier to me, and a bit more brittle.
Plastic? Wouldnāt that cause melting if the resin kicks too hot?
Sure doesā¦use wisely.
Hi Guys,
Q-cel (POTTERS BRAND) and Microballons (3M Brand) are competing brands like Coke and Pepsi. Both are glass bubbles that helps increase the sand ability and increases the viscosity of your resin. Any time you add a foreign object into polyester resin chemistry, it will retard the curing time somewhat, but not significantly, it depends on how much is added. A little extra catalyst will help (2% instead of 1%).Also, the instructions I was told was to never go over 50%filler / 50% resin, although I have talked to people that have with no problems.
Good luck!
https://fiberglasssource.com/collections/resin-thickeners-fillers
http://www.pottersbeads.com/LinkClick.aspx?fileticket=a12swB0MN8w%3D&tabid=348&mid=1025