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Dumb question on sealing large areas of putty


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So Im working on the 1:48 B-1B wings at the moment: installing the mechanical flaps set, and some places need some large quantities of putty. After said and done, I need to rescribe some panel lines and paint. What to do here? Rescribing is obviously going to damage the putty, and the putty itself is going to be blatantly obvious when I put primer over this area. So how would I get a decent surface on this large body of putty? Its more porous than plastic, and Id like it to not be so obvious if I can help it.

Edited by utley
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If you go easy with a scribing tool, I’ve found Miliput to hold up and look decent. I really dont use any other filler putty anymore except small amounts of CA and Mr Surfacer for small blemishes.

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Well here's my issue - these flap mechanisms: the leading edge slats and spar in the mechanical flap set doesnt match the panel lines on the wing molds. Cutting them out per the diagram, the leading edge just doesnt mesh up 100% and Im having to fill in some big areas, not to mention some large surface areas with the trailing edge flap and T/E beam where I had to cut into the wing about 1/8" further fwd on the inboard side and now the lines dont match at all. Its a big area. I am using Milliput superfine for the large, deep areas and using Perfect Plastic Putty for the large/shallow areas. I still get an area of paint that looks coarse over these areas whereas over the plastic it looks smooth.

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If it were me, I'd use the red Bondo which can be found in automotive stores. It sands and feathers much better than anything I have used, and can be used to cover large areas (automative putty after all). But if you have already applied something else, and are concerned about the mismatch in surface porosity / reflectivity, yo ucan apply a finer putty on top of what you applied (I'd suggest Bondo again).

 

For rescribing, I'd try to avoid anything that has a pointy tip (like a pin scriber) or that has a v-shaped grooving profile (like UMM's rescriber). Most putties would either chip or resist being scribed cleanly (even depth) or a straight line. Instead I'd use a fine razor saw in many careful passes (first few most critical) to slowly form the panel lines. Micro mark and UMM have them.

Edited by Janissary
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I have a fine razor saw. Ill take a look at some Bondo, thats not a bad idea...just have to be able to justify the cost for the actual amount Im going to be using.

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2 hours ago, utley said:

.just have to be able to justify the cost for the actual amount Im going to be using.

I say this without knowing if finances are like mine got a couple times jobs were lost long-term; there is an overgrown toothpaste size tube of Bondo spot and glazing putty available at places like Walmart for a little over three and a half bucks; it is what I get.

https://www.walmart.com/ip/Bondo-Glazing-and-Spot-Putty-00907ES-4-5-oz-1-Tube/16927984

 

Oh, sometimes after the tube has gone unused for a month or so, some of the solvent can puddle on top, so I take a brass rod and carefully mix it in the tube, just a bit, being real careful to maintain awareness of where end of metal rod is in relation to side of tube!

Putty which sticks to rod can be scraped on to whatever applicator you use, often an old small narrow  X-Acto chisel blade for me.

And that blade fits in tube opening too.

Edited by southwestforests
added usage info
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Rescribe using one of the Tamiya 0.1mm fine blade saws. That will rescribe without ripping the putty.

 

Priming it very much depends on what putty you are using. Some are better than others. Fill the bulk with something like Humbrol, leave it a good few days and then sand it all the way down to a polisher or maybe roll with some Tamiya extra fine white putty. But you will still need to sand down to a polisher pad. then prime only the putt with something that puts a skin on it like one of the Vallejo PU primers.
You shouldnt get any bleed through with that in the way. But your top coat choice will then matter.

 

What paint will you be using?

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Not sure yet...Im used to Mr Hobby Gunze paints and Tamiya, but I might give AMMO Mig a shot this time. Ill be using either Mr Surface 1000 for primer and/or Floquil for the most part.

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Pictures of your issues would help a lot. It's hard to give advice on something without seeing it. You obviously will have to prime the areas and possibly sand and prime again to blend everything in.

Steve

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Well it is kind of a common problem; different surfaces have various porosity and texture is obviously going to change. Ideally, the goal is to get the reworked area as smooth as the surface its on For example: I had this issue where I used CE glue as a filler, and priming showed these areas as incredibly smooth in comparison to the rest and bled through 3 layers of primer and paint. The smaller the paint particulate, the deeper its going to penetrate, the more its going to take to fill up the pores. My goal here is to fill those pores up before priming.

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Then you'll need what we use to call "Nitro Stain" in my body shop days. Once we did the bondo work, we primed the area and them added the Nitro Stain to help fill the tiny pores and sandpaper scratches. This was all wet sanded, dried and, re-primed again to see how the area looked.

Steve

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Here's what I did when I added the resin wings to my S-3B and ES-3A. I put two coats of Mr. Finishing Surfacer 1500 to check my sanding ( 320 grit ) that I did to the seam and carefully re-scribed the areas that need it. Then I added some Tamiya silver putty to the seam. This area was wet sanded ( 600 grit ) and re-primed with another two coats to check things. I always wet sand whenever possible because it gives you a smoother finish and reduces the chance of scratches. I didn't notice nor see any difference between the resin wing area and the plastic of the model at this point,it all blended together just fine.

Again, not being able to see pics of whats happening, I think your issue is the grits of sandpaper your using between priming and painting.

Steve

 

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Edited by A-10 LOADER
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Here you go. I also have their white putty #87095. This tube is probably 5-6 years old.  I really don't use these types of putty / fillers much for two reasons, #1 they shrink and, #2 you have to wait a while ( usually overnight ) for them to dry. I prefer to use Loctite Super Glue Ultragel for filling my gaps/seams. Hit them with some accelerator and start sanding.

I used the Tamiya putty in this case, instead of the CA, because the resin wings were soft and I didn't want to sand any more than necessary. I also put a heavy coat on because I didn't want to have to do this more than once.

Steve

 

(edited)_IMG_7264.JPG

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I've had some good experience with Tamiya basic type putty and Olfa P-cutter. Just go very gentle on the putty. For normal filling work I use something lighter, like the Humbrol putty, which shrinks, but dries quite quickly. And also sands easilly. But for rescribing it's terrible. Putty flakes off. Tamiya doesn't for like 90% of the time.

Other than that, Miliput is good for scribing. But I prefer tube putty.

I find the Tamiya putty to be most similar in scribing to plastic (but absolutelly not the same!!)

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Ok I got some new scribers and Im going to put some of these techniques to work this weekend hopefully. Still got some areas to work on this before I start going crazy, but here you can see where Im going to have the most issues as it runs basically the entire length of the wing. Yep, all those skin panels are going to need rescribing after I get done with that trailing edge beam.

244982477_1677857802575199_1694326332541897524_n.jpg

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Personally, I’d fill the really large gaps with some plastic stock cemented in with you favorite plastic glue (I personally like Tamiya), and use superglue over the top. Putty has its role, but I find it to be limited these days. It also doesn’t have much strength itself and it looks like some of that area on the left (inboard) flap insert doesn’t have a lot of foundation for putty. Superglue will blend in rather well with plastic, although I still find a primer coat helpful to unify the different smoothness/porosity of superglue and plastic. It scribes fairly well too. I find cutting scribers or micro saws to work best in superglue. It dries harder than plastic and I find needles/gouges to jump and be hard to guide in superglue. 

Edited by ESzczesniak
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