Sandable Filler... how to mix/make your own

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#1

wanting to mix my own filler to use for repairs on molds using the resin system currently in place. also to be used on parts as they come out. since we use an epoxy resin, i’d rather make a filler out of epoxy than poly for the final repairs.

was wondering what talc was used for since i saw it on the FG website as a common filler of any bodyfiller. I’m using a 1:1:2 mix of resin (w/hardener):phenolic bubbles:cabosil. It sands not bad and has a good thickness, but I want to make my own mix and any guidelines or how to that you guys have come across would be great.

I did a quick search but didn’t find exactly what i wanted.

#2

I have always used the glass bubbles and the cabosil. I am not sure of anything else. and I am not as worried about ease of sanding as I am about how it holds up. In some instances you can minimize sanding by waxing and polishing two times around the patch areas before grinding out the repair areas. this assures wax to the edge of the repair area and when you wipe in your filler, you can also apply tape over it. I do this to minimize filling and sanding. sometimes I have to refill, but it is easier than a lot of sanding.

#3

does nobody else dothis, or have any interest. Seems to me that mixing up your own filler with the same resin/hardener would make a much stronger part.

#4

I use a couple of different fillers depending on the application.

  1. Collodial Silical/Phenolic Microballons

  2. West System 410 Microlight & Collodial Silica - extremely light and easy to sand. Not recommended for structural applications.

The ratios are completely on the fly and I add to get the desired consistency for the job.

I also make an epoxy surface coat for certain molds that are going to either be masters, or will have alot of parts pulled. It consists of collodial silica, talc and aluminum powder. I mix the fillers together in an electric coffee grinder to blend them all together and get rid of lumps that would be too tedious to work out when added to epoxy. I do this ahead of time and store the mixture for future use. The collodial silica makes this filler very fluffy after it’s been mixed. I add the filler to the epoxy and measure on the fly to get the consistency for the job, which is usually slightly less viscous than commercially prepared surface coats.

Bob

#5

i’d be very interested in your recipe for that fluffy mix, it sounds like something i could most likely use.

#6

…mix the additives into the resin to the paste thickness before you add cataylst too…

#7

does that aid proper wet out of the slurry before catalizing?

#8

No, but it gives you time to get the right thickness before it starts to gel…