Hello everyone,
I’m looking for a low budget alternative to “micro glass baloons” because buying them online plus the shipping cost is not so cheap. Have you got any suggestion for a “wallmart” alternative?
I need to fill a polyester resin to make a modelling putty, no mechanical properties required, I only need to easy sanding it to a regular surface, black coating and polishing.
I was thinking to low quality gypsum, will I have “chemical” issues?
Thank you
Talcum powder will work and is dirt cheap. Look for baby powder or just talcum powder in the baby or cosmetic area of a store.
What about just trying regular polyester car body filler.
It’s already exactly what you are trying to make, in can and ready to go.
Automotive body filler is precisely that, polyester resin loaded with talc.
You mention polishing though, so it’s probably worth mentioning that any fillers that reduce the density of the resin (making it easier to sand), will also increase the porosity of the resin which means it won’t polish up nicely.
Thanks everyone for the answers, I was looking for something extremely cheap, I just need to sand it easily, than black coating and polishing.
I don’t have to polish the filled resin.
Yes I know talcum powder is cheap, but not so cheap 
I have to totally cut down costs of this step.
I made some Google search and I found that the cheapest filler used for resins is the used coffee powder, it’s not very professional but it seems to work when completely dried.
I’m making some experiments and will tell you tomorrow the results.
For the moment plaster/gypsum filled resin results in a lot of minibubbles inside the hardened compound.
My plug is out of styropor. Can I add talcum to epoxy and achieve a similar compound as polyester fillers? What is the mix proportion? Thanks
You won’t quite achieve something that is exactly the same as your regular off the shelf polyester body filler. Epoxy is harder to begin with, so it’s not as easily sanded. But mainly polyester body filler also has a few other ingredients, such as zinc and Hattonite. Hattonite especially is noticeable because it makes the compound easy to sand, whilst also reducing its tendency to clog sandpaper.
That said, if you’re only doing it for a small job then go for it, you can still make a fairly easy to work with filler. I just wouldn’t be slathering it on a boat hull and expecting to do the same amount of work as a polyester would take.
For what it’s worth, talc is cheap but microballoons (glass bubbles, whatever you want to call them) do make a better filler.
Thanks for the info. The problem is that Epoxy with microballons is a pain to sand and is pretty hard to apply evenly, as it is not creamy. I have worked with alexit blade repair that was great, however was very expensive considering that i need dozens of kg.
You need to test the compatibility of the materials. For Styrofoam polyester resin (in body filler) will dissolve the foam. For something this large you are going to need a specialty filler.
One option is drywall compound. Another option is theatrical prop making surface coats. These are used to cover Styrofoam and other foams routinely without dissolving the substrate.
You can seal drywall compound with orange shellac to create a surface for a splash mold if your going that route.
One other option is styling clay which can be shaved/scraped, polished and molded very easily.
Ok if you are using a Styrofoam or similar then you must use an epoxy based resin otherwise your foam will dissolve.
Yes micro-balloons kinda drys out and does not screed very well although it is easy to sand.
You can buy pre mixed epoxy filling/fairing compounds.
If you want to make your own material with epoxy resin then I would try West System 410 Microlight fairing filler. Much more cream like and screeds nice, easy to sand.