1/96 Thor Sturgeon Build

[thor]

Re: 1/96 Thor Sturgeon Build

Micro ballons are more of a screeding agent: Here is the text right off a technical site that sells the material:

These hollow glass spheres(microballons) make a lightweight sandable filler when blended with resin. Use to fill fabric weave, shallow blisters and surfaces of core materials. The average bubble is less than 70 microns, about a quarter of a grain of salt. It is this small particle size which makes the paste so easy to spread evenly.

#23 Fumed Silica(Cabosil) is a fine grade fumed silica thickening agent similar to Cab-O-Sil and is added to resin systems to prevent run-off and sags on vertical surfaces. Mix in the ratio of 1 part by volume #23 to 2 parts resin for general use. Cab-O-Sil is a registered trademark of Cabot Corporation.

Micro ballons are intended to be used in small, very thin layers. It does not sand nearly as well as cabosil(fumed silica), which is made to be a thickener for use in larger applications such as fillets, fairings, etc. Cabosil has a hardness that is very close to most long cure epoxys, therefore it will sand without leaving high spots on the surface. Micro ballons are much harder than fumed silica. They should be used with long cure epoxy(2 hr cure or longer) to get best results. Short pot life epoxies have a tendency to be gummy when sanded. Cabosil provides a much stronger fillet than microballons as the epoxy actually penetrates the cabosil chrystal, not so with a micro balloon.

[greenman407]

Re: 1/96 Thor Sturgeon Build

Cool. Where can I buy it?

[thor]

Re: 1/96 Thor Sturgeon Build

Here you go...

http://www.fibreglast.com/product/Thixo ... 23/Fillers

[greenman407]

Re: 1/96 Thor Sturgeon Build

Thanks, What I am looking for is a filler thats easy to sand but doesnt shrink or crack over time as does spot putty. There is nothing that I hate worse than doing a nice filler job and sanding it down just perfect and putting a good paint job on it only to have the filler shrink over time and the joint look terrible and you have to redo it. Bondo body filler seems to get so hard so fast and is sticky, hard to sand. Perhaps the body filler Caswell sells is better? I think they call it Evercoat metal glaze? Or would this stuff you sugest mixed with 2 part epoxy be my answer? I hope we are not getting to far off the subject of this build.

[thor]

Re: 1/96 Thor Sturgeon Build

evercoat everglaze is a glazing compound for body work on automobile panels. It is meant to be spread in extremely thin layers to cover small imperfections. It is also a polyester product...just another version of bondo...

[greenman407]

Re: 1/96 Thor Sturgeon Build

Ok so If I have a deep joint between two sections of fiberglass say 3/16" to 1/4" deep, what it the best stuff to use?

[thor]

Re: 1/96 Thor Sturgeon Build

If the base material is epoxy glass, use epoxy thickened with cabosil to fill the gaps. You will need to use some body putty in VERY thin coats with spot putty over this to finish it out before final priming for paint.

[greenman407]

Re: 1/96 Thor Sturgeon Build

thanks a million

[tommydeen]

Re: 1/96 Thor Sturgeon Build

Matt.. We have been using this stuff called "rosathix" to thicken our epoxy resin, have you ever herd of it?
we also use "mild fibres" for added strength on joints as well. we got this stuff from plasic-care in town here.
It seems to work well we havent had delaminations. we always use like materials for bulkheads and the like.
we also use the good resins ie; west systems or the top shelf stuff that Matt uses from Fibreglast.
Tom

[thor]

Re: 1/96 Thor Sturgeon Build

Tom,

I have never heard of that particular thickener.

Matt

[Guest]

Re: 1/96 Thor Sturgeon Build

All fillers will shrink unfortunately. Epoxy has the lowest shrinkage (so low in fact you can generally ignore it). I've only used epoxy putties from Milliput, and these tend to be rather stiff, and hard to sand, and thus ill suited to covering large areas and parts of a job that require feathering etc. They are totally waterproof however and tough as old boots once set.

Polyester filler shrinkage is much higher, how much this affects your job depends on how thick you plaster it on. My own experience with this stuff, is that works well for most jobs, but you need to let it sit for a few days before giving a final skim, to allow it to fully cure. Even then, don't be surprised if you find that you get a bit of shrinkage over the following months.

One part stoppers are really only designed for pin holes and scratches. I use acrylic putty (3M Acryl red) which is great, and low in shrinkage, but I wouldn't use it to cover anything thick.