What to use to fill sink holes

[o-man]

Got MPC 69 Mustang with rather large sink holes in each front fender. What would you guys recommend to fill?

[John Pol]

you can always use plastic rod stretched. What mean by that is put a flame to it and stretch it with a lighter. Drill the sink marks out and install the plastic in the hole.Once dry sand it down to the body prime it and see if it needs spot putty. if so put some spot putty on the area and sand and prime again. I hope this helps you out.

John Pol

[PowerPlant]

Most two-part epoxy compounds will do the job quite well... I prefer Tamiya products.

[Jantrix]

I cut a small piece (but larger than the hole) of sprue and use a liquid cement to glue it into the sink mark. When the plastic gets soft I squeeze the sprue further into the hole. Let it dry and sand smooth. Only a small bit of putty needed for the sake of perfection.

[Ace-Garageguy]

Correctly mixed (imperative) polyester TWO-PART automotive glazing putty is by far the easiest solution, in my opinion. Also imperative is to scuff the bare plastic THOROUGHLY with 180 grit paper to ensure adhesion. I prefer Icing, but I always have it in stock for 1:1 work. One tube would last the average modeler forever, but it tends to dry out over time.

A lot of guys seem to like the Bondo brand TWO-PART polyester filler, which comes in a smaller package.

Both materials have to be mixed with the catalysts that come with them, and they have to be mixed CORRECTLY. Too much or too little catalyst and you WILL have problems.

The ONE-PART glazing putties are simply thick lacquer primer paste, and will shrink badly over time if applied too thick.

.

Edited April 29, 2013 by Ace-Garageguy

[jaymcminn]

+1 on the Bondo 2-part glazing putty. I used to spend a fortune on Evercoat Glaze-coat only to have most of it go bad. The Bondo is very good quality in a smaller size at a great price.

[Longbox55]

+2 on the Bondo.

[High octane]

I just picked up some of that Bondo last week and I'll have to give it a try.

[Miatatom]

To ensure that you get the correct ratio of putty and hardener, use scales that measure in tenths of a gram. Harbor Freight has them on sale now for about $6.

[Edsel-Dan]

I do the drill out, Evergreen/sprue fill.

Materials match

[Guest]

I have used Squadron white putty for around fourteen years. No mixing. No waste. The only time there is noticable shrinkage is when it's applied very thick. Even then, it's minimal. It will not shrink over time after it has dried. I have several models to prove otherwise. Thin applications take 30 minutes at most. Thick applications of a 1/4 of an inch can take a couple of hours or more. You don't have to rough up the surface to ensure that it will stick either. White putty literally melts into the styrene. I've done some crazy stuff with it over the years and have never had a single problem with it. As always, primer is a must before paint.

[Ace-Garageguy]

Roger, I'm not arguing...just that the problem I've had with any of the lacquer putties, like the Squadron green, and the old red body-shop stuff, is that, if put on thick, the surface skins over quickly and inhibits the evaporative drying of the under-layer. Also, because the stuff dries by evaporation of lacquer thinner, when you get your bodywork perfect and then hit it with lacquer PRIMER, it first swells as it absorbs thinner from the primer, and then shrinks back as the primer dries. Again, the surface of the primer skins, inhibiting evaporation of thinner that was absorbed by the filler. I've sanded the primer-over-1-part-filler surface perfectly smooth (1000grit) after a week of drying, painted it, polished it to show-quality, and after a few more weeks, had it shrink enough to be noticeable to a critical eye (and require re-sanding and polishing). I just don't have these issues if I use catalyzed products for heavy filling and mods.

On the other hand, the one-part putties work very well for me if I use them only to fill really small imperfections. No complaints there.

I'll have to try the Squadron white.

Edited April 30, 2013 by Ace-Garageguy

[Art Anderson]

I hit on using "gap filling" CA glue for filling sink marks years ago. I use it with Bob Smith Accelerator which sets the CA quickly, does not damage the styrene; and finish off with needle files and sandpaper. It may well take several applications to do this, but it works quickly, and never shrinks.

Art

[Guest]

Roger, I'm not arguing...just that the problem I've had with any of the lacquer putties, like the Squadron green, and the old red body-shop stuff, is that, if put on thick, the surface skins over quickly and inhibits the evaporative drying of the under-layer. Also, because the stuff dries by evaporation of lacquer thinner, when you get your bodywork perfect and then hit it with lacquer PRIMER, it first swells as it absorbs thinner from the primer, and then shrinks back as the primer dries. Again, the surface of the primer skins, inhibiting evaporation of thinner that was absorbed by the filler. I've sanded the primer-over-1-part-filler surface perfectly smooth (1000grit) after a week of drying, painted it, polished it to show-quality, and after a few more weeks, had it shrink enough to be noticeable to a critical eye (and require re-sanding and polishing). I just don't have these issues if I use catalyzed products for heavy filling and mods.

On the other hand, the one-part putties work very well for me if I use them only to fill really small imperfections. No complaints there.

I'll have to try the Squadron white.

I've never had that problem with Squadron white putty. Now, the red body shop stuff, yes! I only used that junk once! If I have a model that has had a lot of putty applied to it and thick in areas, I spray a couple of very light coats of primer first (allowing about ten minutes between coats), let it dry for a couple of hours, barely sand it, then begin spraying the wetter coats. It keeps the putty from absorbing the primer and becoming soft again. If I'm in a hurry, I'll simply brush a coat of future over the areas with putty and start layin' the primer on.

[Tom Geiger]

I'm with Roger, I use the Squadron green putty for most everything. The key is not to apply it too thick. I will do a thin coat and let it sit over night. Some of the work I've done, like blending panels together on a custom, will take a couple nights to get the putty on in thin coats and sanded.

Now does anyone know if there's a difference between the green and white?

[Skip]

The sink holes you showed on the Mustang, probably Bondo 801 glaziing putty or CA glue and baking soda and lots of block sanding with what ever fills the holes.

[Blown03SVT]

The sink holes you showed on the Mustang, probably Bondo 801 glaziing putty or CA glue and baking soda and lots of block sanding with what ever fills the holes.

In regards to the baking soda and the CA glue... does the soda react with the glue somehow or is the fine powder a binder for the glue to thicken it and fill? Could you substitute and use something like talcum powder with the same results?

[Ace-Garageguy]

.......Could you substitute and use something like talcum powder with the same results?

Ground, powdered 'talc' is in fact the inert material in many 'bondo' style catalyzed fillers. Commercial 'talcum powder' may have other ingredients in it that COULD cause a problem. I don't know. Microballoon is another excellent thickener (used by RC airplane folks), which I use to make an epoxy-based paste where extra strength and light weight are required.

Edited May 1, 2013 by Ace-Garageguy

[Blown03SVT]

Microballoons sounds pretty promising. For years I have done all my seam and sink mark filling with green putty. I need to check Tower Hobbies to see if the have MicroBalloons.

[Guest]

Now does anyone know if there's a difference between the green and white?

One is green and the other is white. Seriously though, I don't know the difference. I've heard there was a difference in setup time in that the green takes longer and seems softer than the white. But, I can't confirm that. I chose the white because I thought there may be a problem covering the green with primer and that it could possibly bleed through on a light color.

[Tom Geiger]

One is green and the other is white. Seriously though, I don't know the difference. I've heard there was a difference in setup time in that the green takes longer and seems softer than the white. But, I can't confirm that. I chose the white because I thought there may be a problem covering the green with primer and that it could possibly bleed through on a light color.

Ah, one of the mysteries in life. I've held the tubes next to each other at the hobby shop and the text is exactly the same. I wouldn't be surprised if it's the very same stuff, with the green being for military modelers and the white for lighter color models, just for the reason you state... easier to paint.