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Hi all, I’m still not 100% happy with my gap-filling game. I’ve done @convair990a ‘s method with the thick CA and the packing tape, mostly with positive results, but I find it time-consuming to get right, and the CA takes a long time to cure before sanding. @authenticairliners and @lichtjahre use a 2-piece boat putty that’s sadly not available in the US, so I’m looking for alternatives with the following properties:
- Tackier than Milliput turquoise so that it can fit in 1 mm and smaller gaps without crumbling.
- More viscous than CA so that it doesn’t run into mount holes.
- 2-part putty that won’t shrink (to make measuring it out easier).
- Easy to cut along an edge before it’s fully cured (like Sergey does) to reduce sanding times.
- 5ish minute working time, 30 minutes to partial cure, <24 hours to full cure (less important on this one)
- Available in the US.
What are some things you all recommend?
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I’ve always had good results with this 2 part product…
Alan Aronoff
Where there's a will, there's a relative.Me as well….. 24 hour full cure…. can be drilled, sanded etc…. minimal shrinkage
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Thanks for the recommendation, I’ll go get some of that and play around with it.
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File under Your Mileage May Vary…….I tried using Apoxie Sculpt to redo a 707 nose. I used way too much and things turned into a gummy mess. As I mentioned earlier I’m using 2 part auto Bondo now. It “smells” so I have to mix, apply, and sand it outside. Figuring the proper amount of hardener can be a challenge to have some working time as well
Ken
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I use Liquitex Professional Modeling Paste, or Professional Light Modeling Paste. Michael’s sells store brands of these Pastes that might affect a painting or sculpture, but for filling gaps on a model that is painted, I haven’t seen a difference. These materials are acrylics, and air dry to a near rock hard consistency. Here’s the trick. You sculpt the material into the gap the just like green stuff or some other modeling putty. BUT, you can use wet cotton swabs to fully clean up the surface of the model while the paste/medium remains in the gap. But fully clean up the material on the surface of the model, the paste will both dry rock hard, and attach itself permanently to the styrene. If the first application & clean up has left a shallow trough where you filled, just repeat the application, the paste will attach itself to the previous layer. I’ve been using this technique to fill gaps on annoying kits like the Minicraft 707, and is way less tedious than other methods, since its water clean up.
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Ken and AJ, thanks! I’ll give those a go as well.
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Ken, do you recall the exact name of the Bondo type you use? I’m seeing comments to try the white two-part “Professional Glazing & Spot Putty,” is that what you have? When I search for that, I usually come up with the red single-part stuff that I’d rather not use. Are you using a tub of the “original filler?”
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LH 707.
I’m travelling so can’t check the Bondo stash right now. I know for certain I use/like the 2 part Bondo which comes in a tube with another small tube of hardener. Purchased at AutoZone which is my closest auto parts store. Dries quickly and sands nice without pinholes, shrinkage, or getting rock hard like Super glue.
Ken
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FWIW, I’ve used a number of things to fill gaps, with my current go-to being 3M Acryl White putty. I bought a big tube several years ago, when the Squadron putty I’d relied on for years was no longer available, and it continues to serve me well. There was a slight learning curve but not by much, as every manufacturer’s putty is going to have its own characteristics, and once I figured Acryl White out everything has been fine.
For more intensive mending or construction jobs I use Apoxie Sculpt, although I get the small size with the two flip-top tubs because my modeling time and enthusiasm isn’t what it once was, and it’s less waste if it dries out or goes bad before I can use it all up.
I have been known to use the full-blown Bondo with hardener (or a surplussed can of the Martin Senour equivalent) for really big jobs, although the last time I did that was many, many years ago. It worked, though.
Jodie Peeler
"In any dispute the intensity of feeling is inversely proportional to the value of the issues at stake." - Sayre's Law
Ken and Jodie, thanks for those additions. I’ll check out my local Autozone and see what they have on the Bondo front.
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I have read all these methods with interest because we can all use new ideas. I am a simple kind of guy, I have used Bondo glazing putty with great success. No hardener it dries quickly and is easily sandable. Fills cracks and joints and is not that expensive at all. It doesn’t have shrinking issues at all, and it doesn’t melt the plastic either. It is red in color, I generally empty some of the tube into an old plastic film cannester and to keep it plyable add a few drops of thinner and stir it with a piece of plastic sprue every now and then. I get it at Walmart. Has worked well for me for longer than I care to admit. I have models that were completed with this technique more than 30 years ago. Where I picked up this little tidbit of information was from Someone many of you knew, Helio Belisario from AirJet advance models days and also Clint Groves from ATP models. Helio was a master modelbuilder and made models for the industry. He made mostely 1/200 models in many airlines colors. I learned a lot from Helio, he would tell me that the secret to successful model building was keeping it simple. Not to over complicate the methods in the build. Not to worry about what others will think of the finished model as long as you are enjoying what you accomplished in the build.
I hope everyone had a happy Thanksgiving,
Jaime Diaz
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Quick update on this front: I tried AK Interactive putty for a small gap that I needed to fill. It shrank a bit while drying, but had a good fine grain and was spreadable with a wet finger. I’d say it’s good to fill in low spots on surfaces because it blends in nicely. One downside is that it’s slightly softer than resin, so I used Aaron Skinner’s technique of sanding it down and painting on thin CA to get a smooth finish. Once I got good at that technique, it worked out ok, but is cumbersome.
I recently got some Bondo Original, it’s a 2-part with the blue hardener. Before going straight in on a model, I used two test pieces of resin against a third block with packing tape as a mask to simulate an engine pylon gap. Once the Bondo cured, I broke it free. The edge against the packing tape was smooth, and the thin spots didn’t have any flaking:
I cut one of the goopy side pieces while the Bondo was curing, just to see how well that works. On the other side, I left the goopy excess. 5 minutes of sanding with a 120-grit block, followed by 240, got me to this shape:
Again, note the sharp edge, lack of pinholes, and the thin patches not breaking.
Nice good edge by the “pylon gap.” The hardness of the Bondo is similar to the resin, so it blends in nicely:
Conclusions from the whole saga:
Everything I tried to fill small gaps except Bondo and CA were frustrating, time-consuming processes. Here’s the rundown:
- Tamiya putty crumbles and doesn’t go on thin, then is softer than resin when sanding, leading to low patches.
- Mr Surfacer 500 crumbles in the gaps.
- Thick CA goes in the gaps, allows nice thin bits, and provides a nice hard and sharp edge when sanded with 240 and higher grits. If you use accelerator, it’s easy to hold something in place by hand and then hit the accelerator to set the piece, then give it a few hours to full cure. While time-consuming, CA is probably the best solution for a hard edge where you need a perfectly perpendicular join. Downside is that it’s hard and you’ll need to sand carefully.
- Bondo goes nicely into small gaps, doesn’t shrink, sands without pinholes, and gives you about 3-5 minutes’ working time before you need to be committed. You can cut the excess while it’s curing, but because it’s so quick to sand, I think the risk of cutting too much outweighs the 5-minute sanding time. Downside with Bondo is that it’s smelly and toxic, so you should plan to work outside in the snow (like I did yesterday) with a mask on.
I think Bondo will be my tool of choice moving forward for most of these gap-fill exercises, with thick CA coming in when I need to preserve a sharp edge where a sanding block might blunt it. Happy to answer any questions people have about this journey, it was definitely a frustrating one for me.
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