Sanding help

[Sidney Schwartz]

I find that the hardest part of sanding is to avoid sanding the paint off edges and protruding bits. The solution I've come up with is to mask these areas off. I start with 3600 grit and progress through 4000, 6000,8000 and 12000 grits. I leave the tape on for the 3600 and 4000, then remove it and continue. It seems safe to use the 6000 and above grits without much risk of sanding the paint off. This method works OK, but it's time consuming. Are there better ways to deal with this issue?

[stitchdup]

There might be slightly different teqniques people use but they're pretty much all the same. Whichever you feel gets you the best results is the one to use as everyone is different. I do the same thing as you with tape when foiling, and i never thought to do it for polishing

[JollySipper]

1 hour ago, Sidney Schwartz said:

This method works OK, but it's time consuming.

You get out what you put in......

Actually, that's a really good idea. One of those 'why didn't I think of that' moments!

[Bainford]

My method is similar to yours, though I don’t tape up quite as extensively as that. There are often some edges though, where I may be concerned about accidentally rubbing too much, and I tape those. Depending on the situation, I may not remove the tape until I’m ready for the 8000. I find as the years pass and my feel and control advances, I use tape less often. 

It seems quite a few builders don’t like the colour sanding and hand rubbing part of the finish, and will go to lengths to avoid it, but it’s one of my favourite parts of the build.

Another tip for avoiding burn-through; during the body-prep stage, block sand all of the panel gaps. I do it before primer during the mold-line and flash removal process, but also after the initial primer application to test that I got it flat. There is a very slight raised lip that forms along both sides of panel gaps on many kits, some quite significant. You need to get this flat, or you stand a good chance of burning through. Many of my earlier colour sanding attempts would burn through at the door gaps, which puzzled me as it appears to be a flat surface. But I investigated and discovered the lip there. On some kits the door or trunk lid isn’t even on-plane with its adjacent panel, which seems odd given the nature of a mold, but I’ve seen it a number of times. 

My block sanding is done with a vinyl drafting eraser wrapped with either 1000 or 1500 grit sand paper, or 600 for rough work, always wet. 

[Ace-Garageguy]

Taping edges and high points on models to avoid sanding through works very well.

I've been doing exactly the same thing (on real cars too) for decades.   

Bainford's suggestion about block sanding adjacent panels flat is also dead on target.

Molded plastic bodies very often have imperfections exactly as he notes.

[StevenGuthmiller]

Of course sanding through the paint during the cutting and polishing process, (for those of us that do it) has always been an issue.

 

My method for avoiding this problem is probably a little more unorthodox than many, but instead of the usual taping method, or just trying to avoid the body ridges, I accomplish it by adequate paint, (clear) thickness.

It doesn't surprise me at all that a lot of people have this problem when they are using only a coat or two of clear, or eliminating it altogether and sanding and polishing the paint color itself.

 

I began using as many as 5 coats of clear on my projects some years ago, (good, solid automotive clear lacquer) and I haven't experienced any significant burn through since.

Of course I still try to be careful on the high points, but with adequate clear coat depth, it's really not something that appears on my radar anymore, and as a bonus, it's my opinion that the added layers of clear can only act to add more depth to the paint job as well.

 

Granted, using this much clear is only possible if you're using the right materials and techniques.

Some paints and clears dry much tighter and thinner than others, so multiple coats will not hide any detail.

 

As I'm sure many of you have heard from me before, I use as many as a total of 14 or 15 coats of primer, paint and clear combined, yet I have zero issues with detail hide, and my models are able to be polished rather aggressively with almost no issues whatsoever.

 

 

Steve

 

[StevenGuthmiller]

14 hours ago, Bainford said:

It seems quite a few builders don’t like the colour sanding and hand rubbing part of the finish, and will go to lengths to avoid it, but it’s one of my favourite parts of the build.

I will never go so far as to say that polishing is one of my favorite parts of a build, but it's my opinion that it is a necessary step if you want a flawless finish.

I understand that there are those that can somehow achieve that perfect finish without, (and of course those that are fine with skipping the polishing and telling themselves it looks good) but I'm not one of them on either account, and I think that most of us strive to be able to produce as close to an ideal paint finish as possible.

Cutting and polishing is going to almost certainly be the most successful alternative for a good majority of us to being able to lay down perfect paint straight away.

It's been my opinion for a long time that even a great paint job will benefit from polishing.

I feel that it creates a more realistic looking finish, and serves to eliminate that super shiny "hard candy" look that you can often see with raw, unpolished paint.

 

 

Steve

[Ace-Garageguy]

4 hours ago, StevenGuthmiller said:

I will never go so far as to say that polishing is one of my favorite parts of a build, but it's my opinion that it is a necessary step if you want a flawless finish...

It's been my opinion for a long time that even a great paint job will benefit from polishing.

I feel that it creates a more realistic looking finish, and serves to eliminate that super shiny "hard candy" look that you can often see with raw, unpolished paint.

Agreed 100%, though I have very few scale examples to show.

I don't find the dipped-in-syrup look to be at all attractive, or scale-appearing.

But a lot of tiresome sanding and polishing CAN be avoided by learning to lay down a slick paint job.

This is just exactly as-shot, no sanding or polishing. 3 color coats of duplicolor "mica" green and three coats of the old Testors "wet look" clear...but similar results are possible with most lacquer clears. (And a scale appearance would be better achieved if this was sanded and polished too, but of course, with very little orange peel to knock down, it goes a lot faster))

[StevenGuthmiller]

1 hour ago, Ace-Garageguy said:

Agreed 100%, though I have very few scale examples to show.

I don't find the dipped-in-syrup look to be at all attractive, or scale-appearing.

But a lot of tiresome sanding and polishing CAN be avoided by learning to lay down a slick paint job.

This is just exactly as-shot, no sanding or polishing. 3 color coats of duplicolor "mica" green and three coats of the old Testors "wet look" clear...but similar results are possible with most lacquer clears. (And a scale appearance would be better achieved if this was sanded and polished too, but of course, with very little orange peel to knock down, it goes a lot faster))

My observation Bill is that the "dipped in syrup" and "hard candy" look are entirely different things.

When the clear has been applied so heavily that it literally looks as if it was dipped in the paint rather than being sprayed on, that is what I would consider "dipped in syrup".

The "hard candy" phenomenon is a little harder to explain, but to my eye, it's when a finish has a generally "toy like" appearance.

I very often see models with plenty of orange peel that also have that hard candy appearance.

It just looks unfinished in my opinion.

 

I agree with you that laying down a good smooth base is absolutely far more desirable than otherwise, but it's not always possible, and very often unobtainable for some, so rather than just accepting what you get, polishing is an avenue to advancing an average paint job into an exceptional one.

Granted, the smoother you get the paint initially, the easier the polishing process will be, and it might just be my individual expectation, but my sentiment is that ANY orange peel whatsoever is unacceptable. (for me anyway)

I know, I've heard the argument, as I'm sure that you have as well, that orange peel, especially on a factory stock paint job, is more typical than not.

My opinion on that has always been that it's nothing more than a justification for taking short cuts.

I believe that we should all be aware, and there is no confusion in my mind at all, that any amount of "normal" orange peel present on a 1:1 vehicle would be completely and entirely imperceptible when reduced to 1/25th scale.

You would never be able to see it.

I'm fairly confident that it would be exceedingly more difficult to produce an in scale orange peeled finish, than it would be to produce a perfectly smooth, shiny and blemish free one.

 

 

 

Steve

 

 

 

Edited April 20, 2023 by StevenGuthmiller

[Ace-Garageguy]

1 hour ago, StevenGuthmiller said:

...I know, I've heard the argument, as I'm sure that you have as well, that orange peel, especially on a factory stock paint job, is more typical than not.

My opinion on that has always been that it's nothing more than a justification for taking short cuts.

I believe that we should all be aware, and there is no confusion in my mind at all, that any amount of "normal" orange peel present on a 1:1 vehicle would be completely and entirely imperceptible when reduced to 1/25th scale.

You would never be able to see it.

I agree entirely.

All anyone needs to do to prove it to themselves is to look at an approximately 1/25 scale photo of a real car on a high-res computer screen.

No visible orange peel.

Which reminds me of the old saw that "body proportions have to be artistically adjusted to look right in scale"...which is also absolute bollocks, and entirely too subjective and in-the-eye-of-the-beholder to have any basis in repeatable reality.

Again, all anyone need do to see the fallacy of that idea is, again, look at an approximately 1/25 scale photo of a real car on a computer screen. 

Correctly-scaled models appear correct when viewed or photographed from similar angles as photos of their full-scale counterparts, and I've investigated this thoroughly from a variety of perspectives (pardon the pun).  

 

 

Edited April 21, 2023 by Ace-Garageguy
TYPO

[Rocking Rodney Rat]

I avoid all of those problems. I never do any polishing... -RRR

[Sidney Schwartz]

8 hours ago, StevenGuthmiller said:

I began using as many as 5 coats of clear on my projects some years ago, (good, solid automotive clear lacquer) and I haven't experienced any significant burn through since.

 

I've been using 3 coats of clear. I'll try 4 or 5 on my next build.

This is a good discussion. My thinking on the color coat is that more than enough to cover the primer completely is wasted. Is there a benefit to putting on additional coats beyond that? Does it make for a better finish after polishing?

[StevenGuthmiller]

12 minutes ago, Sidney Schwartz said:

I've been using 3 coats of clear. I'll try 4 or 5 on my next build.

This is a good discussion. My thinking on the color coat is that more than enough to cover the primer completely is wasted. Is there a benefit to putting on additional coats beyond that? Does it make for a better finish after polishing?

Before you commit to adding more clear coats, be sure that the clear that you are using is capable of being applied that heavily without covering all of the detail.

All clears are not created equal, and the manor in which you are applying them generally makes a big difference as well. (Rattle can or airbrush)

As an example, If I were using 2K clear or Testors clear lacquer, I probably wouldn’t use any more than 3 coats, especially if sprayed from a can.

The Duplicolor clear that I use shrinks up very tight once it’s completely cured, so even though I spray it from a can, you can use multiple coats.

As far as color coats go, Just enough coats to get a good uniform color is all that I worry about, but depending on the color, and what you’re spraying it over, that can take anywhere from 3 to 5 coats.

And of course, as with most of these things, a lot depends on the type of paint you’re using, and how you’re applying it.

 

 

Steve

Edited April 21, 2023 by StevenGuthmiller

[Bills72sj]

If you want to have really good control of where you sand, try this.

 

[Pierre Rivard]

This is a very interesting discussion about surface preparation migrating to what the paint should look like. I don't think there is only one answer here but there is one key question we should ask ourselves. What is the topic and what should the paint look like to reflect that. Period correct off the factory paint job, meticulously restored car, new race car with vinyl wrap look?

Answer that question first, then strive to achieve the paint to reflect that. Measurement of the paint finish has two key elements : gloss and DOI (distinctness of image). Gloss is the measurement of the amount of light reflected, DOI measures the sharpness of the reflected image. 

Good surface preparation and expertise in paint spraying of Ace's green hood have netted him the high DOI combined with semi gloss look reflecting a great period paint job he wants to replicate. The extensive and meticulous steps used by Steven are key for him to achieve the high gloss and high DOI he would want to replicate a high level paint restoration.

Personally I like a period look of well prepared race cars from the sixties, typically polished lacquer jobs with relative high DOI but medium gloss and I adjust the preparation and material choices to reflect that as best as I am capable of. Not one answer for all, it's about what look you want to replicate.

 

[StevenGuthmiller]

On 4/20/2023 at 4:16 PM, Ace-Garageguy said:

Agreed 100%, though I have very few scale examples to show.

I don't find the dipped-in-syrup look to be at all attractive, or scale-appearing.

But a lot of tiresome sanding and polishing CAN be avoided by learning to lay down a slick paint job.

This is just exactly as-shot, no sanding or polishing. 3 color coats of duplicolor "mica" green and three coats of the old Testors "wet look" clear...but similar results are possible with most lacquer clears. (And a scale appearance would be better achieved if this was sanded and polished too, but of course, with very little orange peel to knock down, it goes a lot faster))

 

 

By the way Bill, I came across this photo on the forum today from a recent show, and it's a classic example of what I mean by the "hard candy look".

 

 

 

 

Steve