TOPIC: Fillers and surface corrections.

[TER-OR]

It's about time we made some sticky topics here.


My thoughts.
Always remember, lots of good info here:
http://www.starshipmodeler.com/tech/techmain.htm

There are a few ways to deal with gaps. If the fit is good, and you can tell this through dryfitting, the best way is to try to avoid any filling. I like to use a “hotâ€￾ cement like Tenax and a capillary applicator for precise application. If you slightly overapply the cement, and squeeze the parts together, a bit of semi-liquid plastic will ooze out of the gap. Then you can buff the area smooth. It works really well with a slightly slower cement like Testors liquid cement, too.

To get a good fit, you may find it useful to sand the mating edges flat on a smooth surface with fine sandpaper. 400-600 grit black wetsanding paper works best. Then I usually tape the parts together at a few places to ensure good fit, then start cementing. This is my preferred method for fuselage and wings.

If there is still a bit of gap, you have a few choices. For a fine line, you can use liquid paper. When it’s dry, you can wetsand it easily. Another product for fine lines is Gunze Sangyo’s Mr. Surfacer 1000. Both of these should coat the area, not just the scratch. The best way I’ve found is to try to coat an entire panel or close to it, if details don’t allow. Then wetsanding can make a nice mirror surface. The idea isn’t to just fill the line, but cover the entire area with a smooth surface.

Another product called Gunze Sangyo Mr. Surfacer 500 has a larger grit than the 1000. It’s for larger fills, depressions, and gaps. This will have more structure than the 1000, but may not give as fine a surface. The nice thing about the Surfacer products is that you don’t need to sand them away. If there are critical details you want to protect or if the gap is in a difficult spot, like a wingroot, you can erode the surfacer with 99% isopropyl alcohol and cotton swabs. It takes a while, but you can really control the process well.

For more difficult gaps there are other options. First, you should try to shim the bigger areas with sheet styrene – if you’re working on a styrene kit. Just glue strips of thin styrene stock in the area, allow it to dry and remove the excess. You will usually need to address a fine gap later, but this will be strong and fills a large area quickly.

Other ways to fill deep or wide gaps are with superglue and epoxy putty. Superglue – cyanoacrlyate adhesive (CA) comes in many types. Gap Filling is useful for larger gaps. You can allow it to cure naturally, or hit it with accelerator. CA should be sanded within a couple of hours, or it becomes much harder than the surrounding plastic. Another option is to fill the gap with baking soda and apply drops of a very thin CA adhesive. This provides structure and accelerates the cure. Resin dust can provide a filling media for superglue, too. If you save resin dust when you sand this is usable. I don’t like doing it, because I prefer to wetsand resin.

Epoxy putty is a 2-part media which cures in a few hours and provides a very strong material which holds its shape and is very durable. It can be thinned with water, proprietary thinners or alcohol, and it can be shaped with brushes or tools. It gives a couple of hours for shaping, and until it’s cured, it can be removed with a wet paper towel. Using a brush and alcohol, excess can be removed before it’s cured, and many times you can completely eliminate the need for sanding. I like to use water as a final step to smooth the putty. A finger or brush can make a very smooth surface.

There are many types of epoxy putty. Plumber’s Friend is a 2-part tape, it’s cheap, but the region where the halves meet should be removed, as it will be partially cured. In the hobby shops you’ll find Milliput, A&B and Aves. I like Aves Apoxiesculpt myself, it cures about the same hardness as styrene, and has a nice fine particle size. I’ll use it extensively in limited-run kits, and in vacuformed and resin kits. Epoxy putty can add substantial weight to a kit, so do be mindful.

There are other materials like Squadron or Testors putties – these are solvent based putties and can shrink away from gap sides. They do tend to be gritty as well. I don’t like them. Bondo (in the tube) is also used by a lot of guys. It doesn’t shrink, but it is solvent based. It dries quickly and has a fine grit, and is pretty strong. Again, I don’t like it as much but it is fast.

[Jonas Calhoun]

Matt Swan has two good articles with good pictures:

Seam filling:
http://www.swannysmodels.com/Seams.html

And one on Mr. Surfacer:
http://www.swannysmodels.com/Surfacer.html

Dan

[Neb]

Another great seam filler is Liquitex modeling paste. It's relatively thin out of the jar, which makes it great for filling finer seams without getting it everywhere except where you want it. ( a good example is a fine seam on the refit E between the base of the neck and the secondary hull) You simply force the paste into the seam and any excess stays thin enough, long enough, that you can wipe off the excess. When I did my refit, the seam literally disappeared and I sanded nothing.
Another big advantage is that it doesn't shrink, dries hard as rock so it can be sanded and even carved, and it doesn't yellow. It's primary use is by artists who wish to add heavy texture, or 3D forms to a canvas painting. (for example) My wife has done some acrylic on canvas using this stuff, and after 15 years it still looks like the day she painted it. In some cases she slathered the paste on over an inch thick!

It's cheap too---I paid $10 for an 8 oz jar at Hobby Lobby. Enough to last me through a hundred models.

[Lt. Z0mBe]

Another great seam filler is Liquitex modeling paste. It's relatively thin out of the jar, which makes it great for filling finer seams without getting it everywhere except where you want it. ( a good example is a fine seam on the refit E between the base of the neck and the secondary hull) You simply force the paste into the seam and any excess stays thin enough, long enough, that you can wipe off the excess. When I did my refit, the seam literally disappeared and I sanded nothing.
Another big advantage is that it doesn't shrink, dries hard as rock so it can be sanded and even carved, and it doesn't yellow. It's primary use is by artists who wish to add heavy texture, or 3D forms to a canvas painting. (for example) My wife has done some acrylic on canvas using this stuff, and after 15 years it still looks like the day she painted it. In some cases she slathered the paste on over an inch thick!

It's cheap too---I paid $10 for an 8 oz jar at Hobby Lobby. Enough to last me through a hundred models.

Judging by the name, is it some kind of latex? Also, you mention it dries "rock hard." Is it harder than styrene? Meaning, I would need to do any sanding before it cures to the point where it's harder than the surrounding media.

Thanks in advance.

Kenny

[TER-OR]

I think it's an acrylic product.

[Neb]

Kenny,

Ter's right---I don't have the product with me right now (at work), but the two ingredients listed on the back said "Marble dust, and, I believe, acrylic polymers". I'll double check when I get home.

There's no hurry to sand, unlike speed-cured CA, it doesn't get "hard as diamond" if you don't go after it right away.

When I filled the small seam between the neck base and secondary hull on my PL Refit, I spent about 10 sec on each side of the neck with 400 grit, then hit it with primer. It literally looks like the neck and hull are one piece. I'm very happy with the results.

[Neb]

Ok, here it is, right from the can's mouth---err---label:

Marble dust, and Acrylic Polymer Emulsion.

Dang, that was a mouthful----how do you chemists remember all them fancy names? (Ter)

[TER-OR]

The same way lawyers remember case names, mechanics remember torque pressures for valve cover bolts etc. It's what we do.

Not that I have much call for using acrylic polymer emulsions...or marble dust.

[Neb]

[Beacher]

Have any of you guys had any luck with clear Woody Goop, or sprue goo? I'd like to fill some depressions in some clear parts, but even using clear sprue from the same kit, it comes out cloudy.

(I'm using styrene in testors liquid cement)

Future is an option,but I'd like something thicker, harder and sandable/shapeable.

Thanks!

[macfrank]

Have any of you guys had any luck with clear Woody Goop, or sprue goo? I'd like to fill some depressions in some clear parts, but even using clear sprue from the same kit, it comes out cloudy.

(I'm using styrene in testors liquid cement)

Future is an option,but I'd like something thicker, harder and sandable/shapeable.

Thanks!

Clear acrylic would work well. It has about the same hardness and clarity as clear styrene, so it'll sand and polish quite well. The stuff is expensive (you can buy it in the cosmetics section of any drug store as an "acrylic nail repair kit". It comes as a white powder and an incredibly stinky liquid solvent (really, it's an amazingly potent odor). You mix a small amount of each, slap the resulting paste on the plastic and wait for it to harden (about 5 minutes). Then sand and polish to get it to turn clear. It works best for small, thin sections. Try it on a scrap peice of clear styrene first. The solvent will glue the acrylic to the styrene.

Clear styrene goo (in MEK or whatever) might work, but it has to be very thin; you don't want the MEK softening the underlying styrene or taking too long to dry.


Frank

[Beacher]

Thanks, Frank. I'll try the clear acrylic.

[MrNobudy]

Another great seam filler is Liquitex modeling paste. It's relatively thin out of the jar, which makes it great for filling finer seams without getting it everywhere except where you want it. ( a good example is a fine seam on the refit E between the base of the neck and the secondary hull) You simply force the paste into the seam and any excess stays thin enough, long enough, that you can wipe off the excess. When I did my refit, the seam literally disappeared and I sanded nothing.
Another big advantage is that it doesn't shrink, dries hard as rock so it can be sanded and even carved, and it doesn't yellow. It's primary use is by artists who wish to add heavy texture, or 3D forms to a canvas painting. (for example) My wife has done some acrylic on canvas using this stuff, and after 15 years it still looks like the day she painted it. In some cases she slathered the paste on over an inch thick!

It's cheap too---I paid $10 for an 8 oz jar at Hobby Lobby. Enough to last me through a hundred models.

http://www.dickblick.com/zz006/18e/

is this the stuff your talking about? looks like it would be located in the painting section. Just wanted to make sure it was what you were talking about before i head to HL to look for it.

would be nice if i knew how to post outside the quotes!

[Lt. Z0mBe]

Have any of you guys had any luck with clear Woody Goop, or sprue goo? I'd like to fill some depressions in some clear parts, but even using clear sprue from the same kit, it comes out cloudy.

(I'm using styrene in testors liquid cement)

Future is an option,but I'd like something thicker, harder and sandable/shapeable.

Thanks!

A trick I try is thickened Future. Set some out for a couple of hours until it gets "syrupy." Apply it to the offending depression. It's okay if you apply too much, or if it "crinkles" as it dries. Repeat as necessary. Once you've applied as much as you think you'll need, let it cure thoroughly, and smooth out with a cotton swab soaked in Future. <--Edit: I meant "Windex" there.

I've actually rebuilt entire canopy sections this way. It takes forever, but it does work.

I hope this helps.

Kenny

[kallen-bortas]

As per some of the "tips" section here, I have used the liquid Super-Glue and baby powder. I used it on my K'Tinga and the process worked really well. I saw at least 3 or 4 articles in the "tips" section on Super-glue and powders.

[sbaxter]

Clear styrene goo (in MEK or whatever) might work, but it has to be very thin; you don't want the MEK softening the underlying styrene or taking too long to dry.

That is the truth; a few years ago I was working on my Hasbro A-wing and got the bright idea to fill a hole left by a removed screw with "styrene goo." Not such a bright idea, I discovered. It took at least three or four months to harden to the point I could sand it smooth -- I had begun to fear it would never harden completely. On the plus side, after it did finally harden, it sanded perfectly smooth -- but I'll never use it in such a large blob again!

Qapla'

SSB

[nicholjm]

I discovered a good way to fill hard-to-reach seams this weekend when working on a non-sci-fi kit (blasphemy!). I had a seam on the inside corner of a 90 degree joint that was impossible to reach by file or sandpaper or fingers. So I took my small spatula and crammed a bunch of Squadron Green putty in the gap. Nothing pretty, just got the gap filled. I waited about five minutes, then I took an old ratty brush, and dipped it in Testor's Liquid Cement, and brushed the cement across the putty. The cement slowly softened the putty, and I was able to "paint it" smooth. The results were not a perfectly smooth finish, but close enough to work (it was a tank hull, OK. Tanks are easy like that). You smart, experienced modelers probably already know this trick, though.

[Lt. Z0mBe]

I discovered a good way to fill hard-to-reach seams this weekend when working on a non-sci-fi kit (blasphemy!). I had a seam on the inside corner of a 90 degree joint that was impossible to reach by file or sandpaper or fingers. So I took my small spatula and crammed a bunch of Squadron Green putty in the gap. Nothing pretty, just got the gap filled. I waited about five minutes, then I took an old ratty brush, and dipped it in Testor's Liquid Cement, and brushed the cement across the putty. The cement slowly softened the putty, and I was able to "paint it" smooth. The results were not a perfectly smooth finish, but close enough to work (it was a tank hull, OK. Tanks are easy like that). You smart, experienced modelers probably already know this trick, though.

You can embark on a similar exercise with Acetone-containing fingernail polish remover. DO NOT USE PURE ACETONE.

I hope this helps.

Kenny

[Pandaphil]

Lately I've been using a mixture of Future, and an old bottle of K&B Micro-Balloons. Works pretty well. Of course, I'm not sure if K&B even makes the stuff anymore.

[Kylwell]

Found a new trick with Aves.

Cheap food handling gloves. You know, those cheapo poly gloves that the lunch lady wears. You can get a very smooth surface by wearing them when smoothing out Aves. No safety solution, just pressure.

And, you don't get Aves goobers all over your hands.

[TER-OR]

That's a good idea. I've been using corn starch to lubricate while I smooth - and apply rolled-out strips of epoxy. The slick gloves would help, too. Interesting idea.

[modelnutz]

A question for you Aves users....
Can you speed the cure ?
Can it be thinned? ( I know that alcohol will thin epoxy...would it work with Aves? )

Modelnutz

[Kylwell]

The only way to speed the cure is heat. Problem with heat is that too much makes other things melty.

I've thinned it down to a kind of slip with their 'safety fluid' and filled engraved detail. Kind of soft when cured but it worked.

[modelnutz]

Dang Kylwell...that was a quick reply.....don't you sleep?

I had heard that you could speed the cure some by using a little extra of one part ( not sure...A or B )

I'm going to give the alcohol a try tomorrow.....I'll report back when the results are in.

[Kylwell]

No.

Well, sometimes.

Maybe.

[DeltaVee]

Does anyone know a thinner for Mr Resin Primer Surfacer? and paint thinner and isopropyl alcohol, Tamiya thinner, and Model Master acrylic thinner and Floquil airbrush thinner don't work.

Bonus question: If it goes on too thick, can it be sanded down, and with what so that it sands down around resin detail? I'm pondering steel wool.

[Lt. Z0mBe]

Does anyone know a thinner for Mr Resin Primer Surfacer? and paint thinner and isopropyl alcohol, Tamiya thinner, and Model Master acrylic thinner and Floquil airbrush thinner don't work.

Bonus question: If it goes on too thick, can it be sanded down, and with what so that it sands down around resin detail? I'm pondering steel wool.

I would give denatured alcohol, turpatine (not turpentine), and lacquer thinner a shot.

I hope this helps.

Kenny

[Kylwell]

It's lacquer based, only thing that'll touch it is lacquer thinner.

Please only post a question in one place.

[DeltaVee]

Thanks. Sorry for the double post. I was trying to save a brush.

[TER-OR]

Thanks. Sorry for the double post. I was trying to save a brush.

Try regular old lacquer thinner, that should do.
Also, it can be sanded - but always wet-sand this stuff.