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Dear members,

I need advice on putty-application, as it seems that I am causing a lot of mess when dealing with them.  It never dries with a smooth surface,  and when I try to sand it, peels off during sanding off, even when left to dry overnight.   Some brands dry into a very hard material which is very difficult to even out. What is your favorite putty, as there are many of them around with different handling characteristics, and why do you prefer that particular one?

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I use two. These are the one's that work for me.

3M blue glazing putty for larger fills. This is the stuff auto body people use for fine scratches and stuff. Sticks tenaciously, dries harder and sands out very smooth.

The other, my most used for general filling is Perfect Plastic putty by Deluxe Materials. I have tried all of the standard modeling puttys and this is my favorite. Some guys have said it dries out in the tube, but I've not had an issue.  My tube is about 2 years old and is just like when I bought it. The tube is designed to be set on the bench with the cap down. This keeps the putty by the opening and keeps the air at the bottom end of the tube.

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I rarely use putties as fillers these days.  But a few tips:

  1. As you build, test fit.  If something doesn't fit, make it fit.  Minimize the amount of filler you need.
  2. Once the parts are assembled, dress the seams with sandpaper to see exactly what needs to be filled BEFORE you apply filler.  As a kid, I used to glop Squadron Green Putty over every seam as soon as the glue was dry.  In reality, I probably sanded off about 98% of the putty I applied.  Less is truly more...
  3. Apply thin layers of filler.  1/32" is about the thickest I will go, and I prefer to go half that (1/64", about the thickness of an index card).

As to the question at hand, my favorite fillers:

  1. CA, aka ACC, aka Super Glue.  I use it either straight from the bottle or bulked out with Microballoons.  I rarely use an accelerator, by the way, nor do I ever use baking soda.  Applied correctly, you shouldn't need to accelerate the bond.  Gel-type works well on wider gaps, the thick stuff is good for the smaller gaps, and the thin formulas work nicely on hairline seams.  
  2. Apoxie Sculp or Superfine White Milliput.  This is to fill gaps larger than 1/32"
  3. Evergreen sheet, strip, and rod.  Again, this is to "pack out" gaps wider than 1/32".  Fit it to the gap, secure with CA or plastic cement (I use Tamiya Extra Thin), let dry, and sand/trim to shape.
  4. Stretched Sprue.  An alternative to using Evergreen.
  5. Perfect Plastic Putty or Vallejo Putty.  I use this to fill small defects.  Apply it, let it sit a minute, then smooth with a Q-tip that had been dampened with water.  Don't wet sand Perfect Plastic Putty--it dissolves in water.  If you have to go back and add more, let the first layer dry completely, then re-apply more and smooth as before.  Don't let the first layer get too wet!
  6. Squadron White Putty.  My former Go-To.  I haven't tried the new formulation, but the old stuff was, well, our standard for many years, especially the Green Putty.  I only used the white because I was building a lot of airliners at the time, and it was easier to cover with white paint than was the Green putty.

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Bondo has worked for me for many years.  I've found the main factor in getting it to stick is surface prep.  Always wipe the area down with alcohol or paint thinner to make sure you have all the grease & dust removed before applying putty.

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Here's my standard response, which probably needs updating:

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. Of the lacquer-based glazing putties, 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. Squadron's white putty is said to be good, but I've not tried it either. 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 or fingertip. 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, let 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 a 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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I'm the impatient type.  I don't like waiting around until the next day while putty cures!  For that reason I agree with EJS that auto glazing putties are really good for this hobby.  My preference is Evercoat glazing putty in the pouch.  Being a glazing putty it has a very fine texture and is a two part putty.  Thus when hardened it doesn't ghost through paint.  It also sandable and paintable within about 30 minutes depending on how much catalyst you put in it. It is also way cheaper than any hobby putty.  A 16 oz pouch sells for about $25. That is enough to do a half a lifetime of models. The pouch keeps it fresh for ever.  

Evercoat 412 Metal Glaze - 16 fl. oz.

I have been using a variation of what Michael and Ralph do.  I test fit the parts and if I can see that the part will need filling, I do so before I glue it up.  A little bit of putty in the seam before you glue it up will result in the putty squeezing out when you push the parts together.  Once everything is cured it is much easier to sand that little bit off the line. Also you know that the seam if filled all the way down in.  Much more efficient than trying to squish it into the seam and making a mess of the surface. 

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Ralph, et al who have used, are using and are no longer using Squadron White Putty.  I have a two pronged experience with the stuff...one good and one bad.  The original putty was an excellent choice for fine to very fine seams due to one trait.  It didn't crack if the joint was slightly stressed.  I used it quite a bit for that purpose.  The new White Putty...or at least what comes in the new package and tube...is a totally different critter.  I've bought, I believe, two tubes and had them replaced by Squadron, so I've had four tubes of the stuff in my hands.  One was returned to a LHS for credit, the others went in the trash.  Here's why.

In every case, no putty came out the nozzle first.  Instead, I got a medium syrupy clear fluid and never did get a solid putty.  Even kneading the tubes didn't help.  Nor did sticking a metal rod down the tube opening and trying to mix it.  Squadron said that they had had problems with a production batch, but that they would send me replacements.  They did.  Same problem.  They went in the trash.  I don't have the time or money to keep trying to find a tube of White Putty that works like it used to.

So what putty do I use?  My old reliable Bondo Spot & Glaze Red Putty.  Available at most auto  parts stores, they've changed the name somewhat and put it in a bubble pack, so you'll have to be persistent when you go looking for it.  Today it's known as Bondo Glazing & Spot Putty.  It's still red, still comes in a 4.5 oz tube.  BUT this change and the fact that Bondo also makes another old reliable, Bondo Auto Body Filler that comes in quart and gallon cans along with a small tube of red creme hardener can lead to confusion at the counter.  Believe it or not, some counter people swear up and down that Creme Hardener and Spot & Glaze Putty are one and the same!  Finally, the Bondo Red Putty is the same stuff that Testors used to market.  Sadly, this is another product that Testors no longer offers.

There is another putty that I bought as a result of the above described counter person confusion when I was out of putty and borderline desperate for some.  I found it at a shop that specializes in professional auto body supplies.  The name?  Nitro-Stan spot and glazing Red Putty 9001.  It comes in a one pound tube, is manufactured by Standard Coating Corporation, is red in color (of course) and contains Barium Sulfate, n-Butylacetate, Kolinite, Talc, TSRN, Stoddard Solvent, Xylenes, n-Butyl Alcohol and Isopropol Alcohol.  According to the back panel, this stuff is Quick Drying, Smooth spreading with no drag, Easy sanding - wet or dry, Excellent adhesion, Minimal shrinkage and Maximum holdout.  Incidentally, if anyone out there is planning a scratchbuilt 1/24th scale B-52, this stuff also comes in quarts and gallons.

As it turned out, I found some Bondo...no thanks to an ignorant counter person...so I haven't used any of the Nitro-Stan yet...or even opened the tube...because I still have half a tube of Bondo that I'm working on.  So I can't report on this stuff from a user's standpoint.  But when I told the counter person what I needed it for, they were not only interested and knowledgeable, they were certain that Nitro-Stan would provide the same results as Bondo and probably better.

Edited by ipmsusa2

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I've only used the "old" formulation of Squadron putties.  I still have most of a tube of White that I bought a few years ago.

The main reason, I think, that I don't use many solvent based putties these days is simply because I do a better job at cleaning up parts and test fitting.  Also, I got tired of having fillers crack, or not scribe, or need repeated applications, so I started using the various combinations of CA, microballoons, Evergreen, Apoxie Sculp, and stretched sprue.  None of those will shrink and fall out of a gap.  Evergreen, used to fill a gap, adds structural stability to the joint.  I can build contours with Apoxie Sculp with no fear of the weeks-long-to-dry issue or shrinkage.  I can use a scribing needle on cured CA.  I can use CA to install and fair clear parts, then polish it glass-smooth.

I still have, as I said, a tube of Squadron White, as well as a tube of Perfect Plastic Putty and Vallejo putty on the bench, and they do come in handy as scratch fillers and (with the latter two) to fill small defects without sanding the surrounding detail away--apply a dab, let sit, wipe with a damp cloth.  

I have tried most of the putties you mentioned.  I stopped using red (I used the Testor/Dr. Microtools stuff--boy, was that a deep red!) and green (Squadron and one of the auto body putties--the auto body stuff was a mint green, while Squadron's was the green we all know) putties because I was building a lot of airliners at the time, and it is difficult to cover red and green putties.  When Squadron's white putty hit the market, that's what I used.

I tried the Tamiya Basic Type, and had a mess on my hands--I filled the wing root seams on a Revell Germany reissue of the Monogram 1/48 F-84F, and the putty generated a bunch of gas bubbles in the plastic that was softened by the putty and in the putty itself.  It must have been a reaction with the plastic, since I only applied a thin skim coat (about 1/64").  I wound up having to remove most of the damaged area and fill it with Evergreen and CA.  It was a royal PITA, and I believe that's when I started using CA as a filler more than I had previously.    

Of course, it helps that I finally learned over the years that less is indeed more...

Cheers!

Ralph

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2 hours ago, Ralph Nardone said:

I've only used the "old" formulation of Squadron putties.  I still have most of a tube of White that I bought a few years ago.

The main reason, I think, that I don't use many solvent based putties these days is simply because I do a better job at cleaning up parts and test fitting.  Also, I got tired of having fillers crack, or not scribe, or need repeated applications, so I started using the various combinations of CA, microballoons, Evergreen, Apoxie Sculp, and stretched sprue.  None of those will shrink and fall out of a gap.  Evergreen, used to fill a gap, adds structural stability to the joint.  I can build contours with Apoxie Sculp with no fear of the weeks-long-to-dry issue or shrinkage.  I can use a scribing needle on cured CA.  I can use CA to install and fair clear parts, then polish it glass-smooth.

I still have, as I said, a tube of Squadron White, as well as a tube of Perfect Plastic Putty and Vallejo putty on the bench, and they do come in handy as scratch fillers and (with the latter two) to fill small defects without sanding the surrounding detail away--apply a dab, let sit, wipe with a damp cloth.  

I have tried most of the putties you mentioned.  I stopped using red (I used the Testor/Dr. Microtools stuff--boy, was that a deep red!) and green (Squadron and one of the auto body putties--the auto body stuff was a mint green, while Squadron's was the green we all know) putties because I was building a lot of airliners at the time, and it is difficult to cover red and green putties.  When Squadron's white putty hit the market, that's what I used.

I tried the Tamiya Basic Type, and had a mess on my hands--I filled the wing root seams on a Revell Germany reissue of the Monogram 1/48 F-84F, and the putty generated a bunch of gas bubbles in the plastic that was softened by the putty and in the putty itself.  It must have been a reaction with the plastic, since I only applied a thin skim coat (about 1/64").  I wound up having to remove most of the damaged area and fill it with Evergreen and CA.  It was a royal PITA, and I believe that's when I started using CA as a filler more than I had previously.    

Of course, it helps that I finally learned over the years that less is indeed more...

Cheers!

Ralph

Ralph, Spot On!  Nothing fills a gap like a good fit.  Having said that, sometimes you need a good surface filler that doesn't ghost through paint.  I use a lot of lacquer automotive paints(I use to be able to get pints and my local auto paint shop so I have a good supply) and ghosting is a real problem because of the harsher thinners.  That is why I went to automotive fillers and eventually migrated to the two part ones.  I also like the economy of them.  At $15 to $25 for a quart of the stuff, you just can't beat the cost per ounce.

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For very fine gap filling I use Artists Acrylic Paint...……...Agree with Ralph and Pete, fitting is better than fiddling!

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I use two puttys - well one putty, one epoxy..  For small gaps I use the Vallejo plastic putty.  I still have it with the needle nose applicator, and with it I can lay down a very thin bead. But the best part is that you can come along and with a wet finger, or cotton bud take off the excess. Or, once it's cured, you can use sandpaper on it.

For larger gaps, and some of these older resin kits have gaps like the Grand Canyon, I use Aves Apoxy Sculpt. A two part epoxy that once mixed can be put in the gap. There's no shrinkage, and the best thing is that you can shape it with a wet finger or tool. Starts drying in 2hrs, and can be sanded drilled into and all that good stuff. Best part - no stink.

Sorry for the commercial. 😉 Just love these products.

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Thank you all for the useful pieces of advice.

What do you recommend for the scratches left behind after filing and sanding the putty-applied part of the plastic?  As sanding with gradually finer sandpapers seems an endless (and in my instance futile) work, is there any practical and effective way for avoiding these ugly scratches from being disturbingly visible even after painting? The primers just fail to cover them sufficiently, at least in my hands. Can a transparent ladies nail polish do? 

Thank you

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Try Dupli-Color 2-in-1 Filler and Sandable Primer, High Build Formula.  It's an acrylic lacquer in a 16 oz rattlecan that will do exactly what you need.  If necessary, follow up with 600 grit or so sandpaper, either wet or dry.  You can find this stuff at many auto supply stores, including NAPA, Auto Zone, O'Reilly's and I think even Advance Auto Parts.  This stuff is my go to primer.  Hope this info helps.

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