How to create an invisible seam?

mawright20

What's a flex-I-file?

Here's the website:  http://www.flex-i-file.com/index.php

As Mongoose mentions, the handle is a tube shaped in a C, or a U.  It has a small pin in each end, and they make little strips of sanding material with loops at each end.  Those fit over the pins and provide tension.  That lets you sand and apply pressure to a specific point, like the seam along the top or bottom of an aircraft's fuselage, for example.

The strips are plastic, and there are three grades of abrasive in the basic kit, each color-coded.  They've got a lot of other products, too, but that's the basic sanding kit.

As I mentioned above, I found it much easier to get consistent and more precise results on subjects like a fuselage, or on a figure, than using a piece of sandpaper held in my fingers.  I wish I had bought the product years before.

mawright20

What's a flex-I-file?

 

I use the "squeeze" technique as much as possible, to get that bead of melted styrene along the seamline, and minimize the chance of a visible seam when the joint has cured.  If there is still a seam, I like using stretched sprue from the kit's sprues and some more liquid cement, or Evergreen/Plastruct scrap, for larger seams or gaps.  Again, I'm trying to use all like material and a solvent designed for the material, if I can, for homogeneity.

I use putty, too, Squadron white, thinned with acetone.  I will either apply the putty to the seam, then dip a cotton swab in acetone and wipe away the excess, which cuts down on the amount of sanding necessary afterwards.  Or I will mix a blob of putty and a couple drops of acetone in a well on my palette, making a home-made Mr Surfacer, and then apply this to the seam with an old paintbrush.  I use Mr Surfacer, too, but I find often that there's shrinkage (Costanza!) and it takes several passes to get the seam to stay hidden, more than I get with either the bead or putty techniques.

The last part of my technique is to use a Flex-i-file.  For years, I sanded by hand, but usually, I didn't get pressure evenly applied, especially on fuselage seams or leading- and trailing-edge seams.  I finally broke down and bought a Flex-i-file and immediately got much better results, pinpointing the pressure right on the spot where it needs to be.

I use either Tenax, Ambroid or Plast I Weld in a Touch N Flow applicator. I put the halves together then run the Touch N Flow tool along the seam, wait a few seconds then squeeze the parts so a ridge of melted plastic oozes out. I clamp it and let it cure overnight. I then use sanding sticks to carafully sand the ridge off then polish with finer grits.

When a partial seam is left, I use the same tool and puddle on some of the thin liquid cement on the area which again melts the plastic and is sanded after being cured.

I use this method and most of the time do not need to use any kind of putty. Even stretched sprue can be used sometimes as a filler depending on the problem. The Liquid glue will melt the sprue and act as a filler.

pilotjohn

Call me crazy, but here is what I recently discovered.  I had some Apple Barrel paint from WalMart as I use the red and blue for small instrument buttons and nobs.  I noticed it can be pretty think.  So I went and got some white which is very thick.  I "dab" it on kind of like you do with Mr. Surfacer.  It is completely odorless, dries in about 15 minutes, and can be lightly sanded with fine grit paper.  It sticks into the small cracks just like Mr. Surfacer.  If does shrink a little, so a couple of coats if needed and then you are good to go. 

A huge bottle for .50 cents too:)

John

 

 

I also use thick paint at times on seams that are not too wide.  I use Testors enamel, which is notorious for settling out and leaving really thick stuff in bottom of bottle.  I use a brush to get some of this thick stuff.  Works well, the flat enamels dry hard enough to sand or file in about twenty minutes.  Doesn't work that well for extreme seams.

Call me crazy, but here is what I recently discovered.  I had some Apple Barrel paint from WalMart as I use the red and blue for small instrument buttons and nobs.  I noticed it can be pretty think.  So I went and got some white which is very thick.  I "dab" it on kind of like you do with Mr. Surfacer.  It is completely odorless, dries in about 15 minutes, and can be lightly sanded with fine grit paper.  It sticks into the small cracks just like Mr. Surfacer.  If does shrink a little, so a couple of coats if needed and then you are good to go. 

A huge bottle for .50 cents too:)

John

Hi;

 Do you really want to create a seam ? LOL.LOL. The truth is , there are many ways to make it go bye-bye . I personally do this ,When dry fitting , I locate the troublesome ones .

 Then I break out my Evergreen strip plastic . Usually .020x.040 . This is used to create better guide blocks for the halves. I will then sand and fit till I can put them together without glue and the seam is almost gone .

 Then as I am gluing , I put tube glue on the parts and push together . I then pull them apart quickly and drizzle Sprue-glue in the seam and re-join the halves . While it's drying I apply Tamiya's green label liquid glue and tape everything nice and tight and in alingment . With the sprue - glue squishing out I let it dry well . At least a week . 

     Then I trim and sand the top and bottom where the seams would be . Hey ! No Seams . Nice plastic and a good surface for re-scribing panels . Note .Never try this after one day . Give it at least a week to let everything gas out and harden . T.B.

You can also use gel super glue or tube glue. I use both and, like Don said, use a small file to smooth out the seam after the glue dries.

I use needle files to smooth the seam after puttying. I find it cuts faster with fewer scratches than most sandpaper.

Real G

I have found that putty tends to shrink when overcoated with solvent type paint.  I have been using stretched sprue sourced from the kit to ensure matching color and hardness.  I heavily paint on liquid cement to the sprue, lay it in the seam, then apply more liquid glue to get everything thoroughly melted in place.  I then walk away for 24 hrs and sand it down the next day.  I don't have long-term data, but all the seams treated thus have yet to show the dreaded "phantom seam".  HTH.

 

I second this one from Real G, sprue filler works perfectly every time. Liberal liquid cement and worked into the seam, sprue does it. Dry overnight, file, sand and prime, hasn't shown up even years after.

Nice save, Goose, oughta be a good build.

Patrick

I have found that putty tends to shrink when overcoated with solvent type paint.  I have been using stretched sprue sourced from the kit to ensure matching color and hardness.  I heavily paint on liquid cement to the sprue, lay it in the seam, then apply more liquid glue to get everything thoroughly melted in place.  I then walk away for 24 hrs and sand it down the next day.  I don't have long-term data, but all the seams treated thus have yet to show the dreaded "phantom seam".  HTH.

Here's how I corrected this. First i used mr surfacer 500 applied with a toothpick. Then after that dried for a day i used the black grit on my flexifile to round it out. Primered with citadel white. The end result is picture one. Still had some seam left. I did a mist coat and then 2 light coats of primer. This built up enough primer that i could sand it off with the brown grit on my flexifile. The end result is the second pic. Much better than my experience with the barrel of the atomic cannon...

Hi,

Thanks for the link and good luck with your build.  I'm interested in seeing how it turns out.

Pat

I found this link which is somewhat helpful. I can see that my initial problem is getting the seam welded together when initially gluing the parts. Good info for the next piece. For now I think I will try the white out method since my final color for the Thunderbirds is gloss white.

http://hawkeyes-squawkbox.com/2008/07/22/encore-perfect-seams/