Filler for a resin kit

[lock4244]

So work is progressing on my M420 build, however I've run into a little problem... while drilling a hole for a grab iron at the rear of the shell, I hit an air pocket and now have a larger hole. Anyone recommend a filler for a resin shell? There are a few other little gaps that could use some attention, too. TIA.

[cv_acr]

Bondo?

[craigolio1]

I use three kinds.  Bondo Glazing Spot Putty.  I use it for filling tiny holes or cracks.  It sands easily but is easily damaged so not great for big repairs.  An example where I used a lot of it was on a resin CPR passenger car shell which had a finger print or tool mark or something, on the master that showed up in all of the casts.  I scraped some of this over it and then sanded it  down, eventually to 1000 grit which provided a nice shiny surface.  The repair didn't need any strength.

http://bondo.com/products/automotive/body-filler/bondo-glazing-spot-putty-937.html

For large holes or cracks I often used to use Squadron, but haven't in a long time.  It works well though.  I always found I had the best result if I went over the finished product with some of the Bondo after though.

http://www.micromark.com/squadron-green-putty-46-oz,6412.html

The one I use now, instead of Squardron, is Tamiya Basic.  I goes on so smooth, like the Bondo, but is rock hard like the Squadron.  Sands very easily as well.  It's Laquer based so use ventilation.  You can thin it with laquer thinner as well and paint it on if you want.

http://www.tamiyausa.com/product/item.php?product-id=87053

I have used all of them on resin with good results.

Craig

[Puddington]

I also use the Tamiya and have had good results.

[up1950s]

Or you can use the resin dust and particles that you have saved from sanding ( you did save that stuff ) , fill the hole with it and soak with ACC , and let dry overnite , repeat as needed . then sand , and yes , save that stuff also .

[randgust]

I'll make two recommendations - and trust me, when you make resin parts you'll try everything at least once...

1)  Squadron green.  Doesn't shrink.  But that green color has a nasty habit of showing through paint so think about that.  I also tend to 'seal' it with watery ACC if it is any position to either pop out or needs reinforced.  It's mildly porous.  Sands incredibly smooth.

2)  Tamiya white.  Love the stuff, sticks like crazy.  But it does shrink.  It's not as hard as Squadron though.   I like it because is nearly invisible in white resin requiring no special paint repairs.

Testors white - too soft, garbage.
Squadron white - similar, what were they thinking?  Not even close to green in effectiveness.
2-part Epoxy - unsandable.
Solvent cement mixes - don't stick
Automobile body putties:  OK if you already have them, most shrink, most need priming due to the red or gray colorations.

[haasmarc]

My recommendation is Devcon white 2-ton epoxy.  I emphasized the white since they have a clear 2-ton epoxy that does not work the same.  It is designed for repairing ceramic items.  You can get it from Ace Hardware stores.  At least that is where I got the last batch I bought.  It takes 8 hours to cure, but it has very nice properties.  First, it is sandable/carvable when cured.  Second, since it has a long cure time, you can wait a few hours and then come back and work with it when it has the consistency of clay.  I use this when say fixing a grill or rain gutter on an F-unit.  Third, if you are filling a hole in a shell, you can put some scotch tape on the outside and fill the hole from the inside and pull the tape when cured.  This leaves a nice smooth surface.  Fourth, it shrinks very little as it cures.  Virtually not at all.  Fifth, when heated it will get flexible allowing warps to be removed. 

When I used to make loco shells to sell, I used it for the whole shell.  Since it is relatively thick, it hangs nicely on the sides of one part molds.  It will run some.  I have used it to make a casting of a solid automobile but turn the mold with the open cavity down so any excess would run toward the bottom.  This gives me a nice thin cross section so I can easily open up the windows and add an interior if desired.


Update:  I haven't bought any in a while.  I still have several packages myself, but I looked for some online and it looks like Devcon might have discontinued the white 2-ton epoxy.  If true I will be very upset as I use this for a lot of applications.

[mmagliaro]

I'll toss in my perennial suggestion of JB Weld 2-part epoxy.  Hardens to a tough rock-like gray.  Can be sanded.  Great stuff.

[lock4244]

Wow, thanks for the great ideas, guys! A lot of options to consider. I did not save and filing shavings, however I've many more to build so I can save them.

Anyone have a suggestion on what to use to clean release agent off resin?

[peteski]

CA glue and accelerator. I use the BSI brand as the accelerator doesn't bubble the CA like other brands. No shrinkage either. Just sand it down within few hours of application because after about a day the CA will be harder than the resin making it difficult to sand.  I absolutely hate and try to steer clear of any kinds of putties. Yuck! 

[briggsmodels]

I didn't see your post until now. If you have a serious void, I will gladly replace the shell. If its a small issue and you think you can work with it, I use baking soda and thin CA. The baking soda is applied to fill the void, then a tiny drop of CA is applied. It will cure instantly and provide a sandable, paintable surface.

[pnolan48]

Since I'm now in the casting business, I've tried everything. Thanks, Peteski, for pointing out that the baking soda/ACC combo has to be sanded early. I'll try it again. I have a small cup of soda on my table, and shock my visitors by calling it my cocaine stash--that much cocaine would probably be worth millions!

I prefer Bondo glazing putty for small surface imperfections. Since my ships hulls are rather large, they will have small air bubbles, and Bondo has a longer working time than Squadron green. I use small scrap pieces of sheet styrene as spreaders, since I can contour them for the surface (i.e., concave or convex), and then just throw them away. The Testors, because it comes out of a very small opening, isn't bad for small imperfections in places where I can't get a spreader or finger in to smooth it out.

[peteski]

Actually, I recommended CA glue and a proper accelerator for it.  I'm not a big fan of using baking soda as accelerator and filler.  Actually, I'm totally against it.

While I don't know the beginnings of the baking soda thing, I suspect it was an accidental discovery by some modeler. It was all the rage in the 90s but I also heard and read about horror stories.   After all baking soda is water soluble.  If the CA doesn't fully seal the baking soda (some remains dry) and there is a pinhole in the glue, there is a good chance that some moisture from the air will get in and the baking soda will start oozing from the filled area.  The chances of that are very small but I have heard of examples where even after few years after a model was finished, stuff from the filled areas started oozing onto the surface.

Why take a chance on a model which took you a long time to build by using a questionable accelerator/filler material?
Why not use something that will not even leave a possibility of oozing out later?  Things like plastic or even wood shavings can be used, talcum powder, microballons or many other non water-soluble materials can be used as a  filler.  Those fillers will not accelerate the hardening of CA glue but that is what accelerators are made for.  On many small imperfections I don't even use any filler. Just CA glue and accelerator. Sometimes I need to apply in couple of layers.  The BSI brand accelerator is relatively mild (and almost odorless) so it does not bubble up the CA glue (like other brands or baking soda do).

I'll leave baking soda for baking and deodorizing my fridge. 

[DKS]

For tiny pinholes, I use multiple applications of thick AC. For larger voids, Squadron green, followed by thin CA to seal it.

On the recommendations of some diorama modelers, I've recently acquired some Tamiya UV putty, but have not yet tried it.