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What is the best putty to use to fill seam lines


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Hey guys i was wandering what was the best putty to use to fill seam lines i am curently using testors model caulk but no matter what i do no matter how much i sand it it is easily seen under the paint and also i apreciate if it was a little on the cheaper side im not a millionare ( wish i was ) any help wouild be appreciated

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Z: Almost everyone has a basic cure for those nasty seam lines. One of the basics from what I've learned (but certainly not the only one) is to properly clean the surface area to be glued after checking the fuselage, wings, or other parts for warps . (That can be rectified by placing the part under hot water (about 160 degrees of temperature) for ten seconds or so (when necessary) to realign the part. Once you've glued the part in place, remove the top residue of glue with an X-Acto blade or medium sandpaper depending on the excessive amount. You should at this point have little need for the putty. If there is residual gaps in the part afterwards, I use Milliput Standard grain epoxy putty. It dries to a hard surface, but after the necessary kneading of the two tubes of the putty, can be messy. So wear some dishwasher gloves if need be, to mesh it. Gradually work the sanding if need be, from 400 up to 1200 grit sandpaper. I usually finish with 2400 to 4000 (sanding pads) before I apply a primer. You should see the seams disappear. Another alternative which I use once in a great while is super glue. These usually are good for the very smallest of tiny gaps but not large ones. I hope this helps you out. Best,

 

Mark

Edited by aAzZ09
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Big, small, narrow, wide, makes no diff to me. I use 3M Acryl Blue. It is a "fine" grade filler for automotive body shops. It's a light blue color by 3M, thus the name, and can be found at various auto parts stores. I've seen it only in 20 oz tubes and the stock # is 05964. I've purchased two in the last 20 years. That 20 oz tube is big. It isn't cheap but then when you compare the volume of putty you get in the 3M tube to other much smaller and cheaper tubes of putty one can buy from a hobby shop it isn't such a bad deal at all.

The putty can be "thinned" with a liquid glue or can be applied straight from the tube. It sands very well and feathers along the edge of the putty plain. Acrylic or Enamel paints both apply well over it and it has yet to crack on any model I've used it on in the last 20 years.

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If all else fails, and you are using a liquid cement that melts styrene (a "hot" glue) then take some spare sprue/sprue nubs/shavings and add it to a container of liquid glue. Once all the plastic melts into a gooey, partially liquid state, apply it like putty; press it into the seams and wait till it solidifies. Sand smooth using the above-mentioned system and you'll have the smoothest seamless joins ever.

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Another tip is to make the gap larger. Sounds counter-intuitive, but it's true. Now, don't go making a big gouge, but maybe dragging an Exacto sideways down the seam a few times. This way accommodates some of those not-so-fine-grained putties.

 

Also, depending on where the seam actually is, don't sand all the putty away. Think drywall. When you mud a drywall joint and then sand it, you don't sand away all the mud. Instead, you feather the edges in and then reduce the "hump" over the joint until it's almost imperceptible. This way, the seam blends in better.

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I'm going to recommend getting used to using superglue and baby powder mixed together! I list the advantages as follows:

1) You can buy the CHEAP super glue (4 tubes/a buck), and use it to glue the kit together. There's no need to buy expensive "super thin" or "gel" types

2) It can be used to glue non-plastic parts to the plastic parts, which plastic cement will NOT do

3) It dries quickly, allowing for faster progress, BUT you do need to allow for proper alignment, so it won't always be the best glue if alignment is fiddly

 

You do NOT want very thin, expensive superglue to make up the superglue/powder "filler". IT will set too fast and you won't have time to put it into the gaps. The CHEAP superglue though gives you a minute or so of working time. Simply put a small pile of powder (size of a quarter) onto an old butter tub lid. Place a drop or two in the middle of the powder. Mix it together with a toothpick until it's a "paste", and then apply it to your gaps. Try to spread it as "smoothly" as you can, but don't worry if it piles up a bit. It'll be dry in a minute or so and can then be sanded. The advantages to this filler are:

1) it's cheap and easy! No need to wear gloves, it mixes faster and easier than epoxies, and dries much faster than model putties (and car bondo), so you can make faster progress

2) it fills larger gaps than straight superglue, and can also be used to build up contours and fill in short shots where plastic is missing, especially if you use it with an accelerator

3) it sands easier than regular superglue, and feathers out nicely if you use 600 and higher grits

4) it can be polished like the surrounding plastic unlike other fillers, which is important for bare metal finishes

5) it scribes better than most other fillers as it's almost the same as the surrounding plastic. Other fillers are softer than the plastic, and straight superglue is often harder than the surrounding plastic!

 

Just another choice to consider! Experiment and see what works best for you!

 

GIL :smiley16:

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  • 10 months later...

I really like the "melted plastic" and the "baby powder" ideas. I'll have to try those next, because I, too, have been looking for an alternative to standard putty.

Thanks for the info everyone.

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The best way to avoid large gaps is to carefully test fit parts before assembly. But if you have a very large gap in spite of your best efforts, it's best to try to fill it with styrene plastic rod/strip and liquid cement, allowing it to dry thoroughly before applying any putty. This technique is handy for wing-to-fuselage gaps.

For filling large gaps, I'd suggest Milliput, which is an epoxy filler that comes in two parts that have to be mixed thoroughly before applying, and can be smoothed with a wet finger/cotton swab/sculpting tool, or Aves Apoxie, a similar product which comes in a variety of colors. Some of the auto body glazing putties, such as 3M Acryl Spot Putty, make good model putties; these are lacquer based and can be applied (sparingly) with a brush dampened in lacquer thinner. I'd recommend Spies Hecker Permacron Fine Putty.

Another useful filler from the auto body repair sector is Evercoat/Eurosoft, also a two-part putty which requires the addition of a catalyst to harden it. A nice thing about it is that before it sets, it gets rubbery, which makes it easy to carve away any excess with your modeling knife, but once cured, it sands and takes paint like styrene plastic. It's available at auto body repair supply outlets.

Tamiya makes some body putties which are said to be quite good as well, although I've not tried them. A relatively new product is Perfect Plastic Putty, a one-part putty which can be smoothed with water, but it is water soluble after it dries so cannot be wet sanded. However, it can be smoothed after application with a damp cotton swab. Many modelers like to use CA glue as a gap-filler and have had success. But it must be sanded immediately after it initially sets up. I've never had much success with it myself.

You can also make your own putty by dissolving sprue in liquid cement or MEK. What's nice about this is that you can control how thin or thick you want your "plastic plastic" to be, you have a variety of colors of sprue to choose from, and once it's set and sanded it takes paint just like styrene plastic, because it is styrene plastic!

 

Mr. Surfacer comes in three "flavors": 500, 1000, and 1200, in order from coarse to fine. They are intended more as primers/surfacers for filling small imperfections prior to painting, not as a general gap filler. See here for a good primer (pun intended) on Mr. Surfacer:

http://www.swannysmodels.com/Surfacer.html

There's also Mr. Dissolved Putty, which is an even thicker liquid putty, but again, it's not intended for filling large gaps. It can be brushed on, however, which makes it really useful.

 

Typewriter correction fluid ("white-out") can also be used to fill fine cracks. Brush it on, liet it dry, sand, and paint.

Putty, regardless of type or brand, should be used sparingly. The lacquer-based putties can melt through plastic components if applied too generously. You can place masking tape on either side of the gap before applying putty. Once the putty is cured, sand it until you can remove the tape, then sand it flush with the surface. Lacquer-based putties should also be given plenty of time to allow the solvents to evaporate. My rule of thumb is: If I can no longer smell the putty, then it's safe to begin sanding.

I'd suggest getting an old kit and a supply of different model putties and body fillers and experiment. Keep notes. You'll soon find a combination of putty and technique that works well for you. Good luck!

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To shanonen I have tried the baby powder and super glue and it works well but indries in like thirty seconds so you need to work fast with it . I recently ran into a older modeler in hobby lobby who swore by tamiya model putty he had been building for 30 years so I thought I would give a try it is only 2 bucks and come with quite a bit in the tube and I will never switch back goes on easy reasonable working time and dries in 2 hours and when sanded becomes basically part of the model you never see it when the model is painted .

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I know some of you will laugh, but I got mine at Home Depot. It's Elmer's Wood Filler in a 3.25 oz tube. It comes in white and golden oak. You can sand it and buff it.

 

Ed

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  • 6 months later...

I've had good results with the various viscountcies of super glue or the Tamiya putty. The Tamiya putty can be smoothed with Mr Color Thinner.

 

For big gaps or seams I've used Apoxie Scuplt. It's a two part putty that can be kneaded into shape and smoothed with a wet finger for contouring then sanded when dry. I used it in the oil cooler intakes on the P-40 in my avatar picture to fill and contour the seams. Also have used it for making seat cushions and head rests.

 

-Ken

Edited by kpatterson
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I still find Gunze Sangyo dissolved putty to be the best. It probably does not work well with wide cracks but has been great for everything that I have used it on so far. I like the control the best. nothing more than a paint brush.

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  • 5 weeks later...

I use the 3m white tube of Acryl-white Glazing Putty. Can be thinned with nail polish remover or lacquer thinner, dries fast, sands well, and no shrinkage.

 

 

 

Joe

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  • 3 weeks later...

For the wide canyons I also use the Aves Apoxy Sculpt. For the medium ones I too have my bottle of chopped up sprue in a bottle of Tamiya Extra Thin. For hairline cracks I use Vallejo plastic putty. Once you get used to the Vallejo stuff, it's great to work with.

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