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schooner

Just When Do You SAND ?

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Hi Gang ( Newbie here ) :smiley14:

 

Want to know.

Afer cleaning part in Dawn soap liquid and take part of the stems.

I guess you primer ?

When do you SAND and with what GRIT ?

 

Any and all info on this subject will be greatly appreciated.

Edited by schooner
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A quick primmer on painting. One of my favorite subjects. Statement #1-Paint hides nothing! In point of fact it can highlight defects in the surface. Paint is not a filler, it is a color coating. A paint job is only as good as the preparation work.

 

Sanding is necessary for two reasons.

 

First is to remove anything you don't want to show, such as mold lines, seams, sprue attachment point, and surface defects such as sink marks and flash. The only way to get a perfect paint job is with a perfect surface to start with. It must be smooth and even so the paint will lay down the same way.

 

The second reason to sand, is to give the paint something to hold on to. This is often referred to as "Key". Even the finest abrasive will leave some scratches in the surface. The trick is to have the smallest scratches necessary to give the paint grip. Sanding starts with a relatively course abrasive paper. I notice that you list woodworking as a hobby. Nothing you use for that except the finest finishing papers will work in this one. Everything else is too course. If you do fine woodworking you are probably already familiar with Micromesh brand abrasives. For this end of the hobby, I use a 3200 grit as the coursest abrasive. I generally go through 4000 and stop at 6000 for a working surface for primer. After primer, 8000 and 12000 are my preferred grits for removing defects. This is because a lot of what I do is glossy finishes. Flat finished you may be able to get away without the ultra fine grits but that is something you need to decide yourself.

 

I always spray a primer before going to the color coats. Again, my preferred primer is Tamiya White. It is a very fine grained primer but covers very well. It is a mild etching primer so with proper surface preparation, it will stick very well. It's dull flat surface gives the color coats a good base to grip to. I generally spray on one thin coat and then sand it off. This will give what is often referred to as a guide coat. As you sand it off, it will highlight surface scratches and low and high spots and other defects. Once you have these all gone, then a final coat and you are ready to lay down your color.

 

I hope this helps. :smiley2:

Edited by PeteJ
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A quick primmer on painting. One of my favorite subjects. Statement #1-Paint hides nothing! In point of fact it can highlight defects in the surface. Paint is not a filler, it is a color coating. A paint job is only as good as the preparation work.

 

Sanding is necessary for two reasons.

 

First is to remove anything you don't want to show, such as mold lines, seams, sprue attachment point, and surface defects such as sink marks and flash. The only way to get a perfect paint job is with a perfect surface to start with. It must be smooth and even so the paint will lay down the same way.

 

The second reason to sand, is to give the paint something to hold on to. This is often referred to as "Key". Even the finest abrasive will leave some scratches in the surface. The trick is to have the smallest scratches necessary to give the paint grip. Sanding starts with a relatively course abrasive paper. I notice that you list woodworking as a hobby. Nothing you use for that except the finest finishing papers will work in this one. Everything else is too course. If you do fine woodworking you are probably already familiar with Micromesh brand abrasives. For this end of the hobby, I use a 3200 grit as the coursest abrasive. I generally go through 4000 and stop at 6000 for a working surface for primer. After primer, 8000 and 12000 are my preferred grits for removing defects. This is because a lot of what I do is glossy finishes. Flat finished you may be able to get away without the ultra fine grits but that is something you need to decide yourself.

 

I always spray a primer before going to the color coats. Again, my preferred primer is Tamiya White. It is a very fine grained primer but covers very well. It is a mild etching primer so with proper surface preparation, it will stick very well. It's dull flat surface gives the color coats a good base to grip to. I generally spray on one thin coat and then sand it off. This will give what is often referred to as a guide coat. As you sand it off, it will highlight surface scratches and low and high spots and other defects. Once you have these all gone, then a final coat and you are ready to lay down your color.

 

I hope this helps. :smiley2:

 

A quick primmer on painting. One of my favorite subjects. Statement #1-Paint hides nothing! In point of fact it can highlight defects in the surface. Paint is not a filler, it is a color coating. A paint job is only as good as the preparation work.

 

Sanding is necessary for two reasons.

 

First is to remove anything you don't want to show, such as mold lines, seams, sprue attachment point, and surface defects such as sink marks and flash. The only way to get a perfect paint job is with a perfect surface to start with. It must be smooth and even so the paint will lay down the same way.

 

The second reason to sand, is to give the paint something to hold on to. This is often referred to as "Key". Even the finest abrasive will leave some scratches in the surface. The trick is to have the smallest scratches necessary to give the paint grip. Sanding starts with a relatively course abrasive paper. I notice that you list woodworking as a hobby. Nothing you use for that except the finest finishing papers will work in this one. Everything else is too course. If you do fine woodworking you are probably already familiar with Micromesh brand abrasives. For this end of the hobby, I use a 3200 grit as the coursest abrasive. I generally go through 4000 and stop at 6000 for a working surface for primer. After primer, 8000 and 12000 are my preferred grits for removing defects. This is because a lot of what I do is glossy finishes. Flat finished you may be able to get away without the ultra fine grits but that is something you need to decide yourself.

 

I always spray a primer before going to the color coats. Again, my preferred primer is Tamiya White. It is a very fine grained primer but covers very well. It is a mild etching primer so with proper surface preparation, it will stick very well. It's dull flat surface gives the color coats a good base to grip to. I generally spray on one thin coat and then sand it off. This will give what is often referred to as a guide coat. As you sand it off, it will highlight surface scratches and low and high spots and other defects. Once you have these all gone, then a final coat and you are ready to lay down your color.

 

I hope this helps. :smiley2:

Hi Pete

WOW! Thank you so much 4 your reply 2 my post.

GREAT info. I sure will save it, so my ol' brain (whatever is left of it ) . . . will remember your suggestions.

I'm so glad I join this great forum IPMS because of guys like YOU !

Thanks Again Pete

GOD BLES

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Nothing to add the Pete's post, but I must say that I love the Senator Bedfellow avatar, Pete!

 

Surprised anybody knows the good Senator besides me! Thanks for noticing.

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I'm a BIG Bloom County fan, though I personally lean towards Bill the Cat (ACK!)! :smiley2:

 

Pete's advice is spot on, and I'm guessing is geared (pun intended) towards painting automotive subjects. The extra fine sanding grits and steps he mentions are absolutely needed to get the high gloss shine finishes car models need. His advice on getting the painting surface prepared properly is dead-on for ANYTHING you're going to build. The only difference between automotive models and military models is that military models generally do not need a glass smooth surface for painting camouflaged colors, so you don't need the super fine grits. However, models with natural metal finishes (aluminum, etc.) DO need a smoother finish than camouflaged models, and require more sanding and surface prep like Peter mentioned.

 

Sanding?

 

For most modeling purposes you'll need 3 basic grits: 100-250 rough grit; 400 medium grit; and 600 grit for fine sanding. Peter is correct in that you start with the rough stuff for tough work and work your way with finer grits to remove the scratches left by the rougher grits. Always start with the finest grit that will get the job done, as it saves on the work needed since you're leaving fewer scratches in the surface. Using a circular motion is best whenever you can, until you get to tight areas that make you sand in only one direction.

 

In my experience, the easiest sand paper to find is the 3M brand wet/dry grits at Home Depot, Ace Hardware, Lowes, and in many hardware departments. You can buy packs of each grit or a variety pack.

 

Many people, myself included, prefer using sanding sticks. Hobby companies like Testors and Squadron make these, and they work well. However, if you have a Sally's Beauty Supply near you (or check any beauty product supply department), you can find "nail filing sticks" that give you the grits you need, and those sanding sticks are usually bigger and cheaper than hobby brand sticks. Sanding sticks are easier to handle. Most of them are foam backed, allowing you to cut them and create a tapered point that allows you to get into tight areas easier.

 

You'll also need a "triple grit" sanding stick that has 3 very fine grits on the one stick. This is (essentially) the equal to the extra fine grits Peter mentioned. You'll need it to fine sand and then polish scratches and mold lines on clear parts.

 

When and where to sand?

 

Models have seams where the parts are joined. You want those joins to either be invisible or to resemble the other panel lines around them on the model. The goal is to make the model look "seamless" in appearance. These seams may be good or bad fitting depending on the quality of the kit you've chosen to build. "Tamiya" quality type models have the reputation of very good fitting parts, meaning less sanding to get a good looking model. Other models, especially older molds, may not fit as well. If you're going to build your Mustang, Google it on-line (ex.- "1/48 Monogram P-51D Mustang") and read the reviews of it. Those will tell you where builders had problems and help you avoid them, or tell you how to solve them. You can also ask about your model here.

 

TEST FIT ALL PARTS BEFORE CEMENTING! See how the seams look. Look for raised areas on the inside surfaces that cause gaps. Make sure the alignment pins don't prevent proper alignment! Sand, carve, and cut as needed to get the best fit BEFORE you glue! This will save you sanding work later on!

 

Make sure your glue has had time to completely set before sanding. If you use old fashioned tube cement, that will require at least a day. Liquid cements and weld cements require at least 1-5hrs, depending on type, brand, and how much you apply. Many of us use superglue, which is almost instant; BUT also allows almost no time for aligning the parts! Balance your choices with your needs and how easy it is to get proper alignment.

 

You may need putty to fill gaps and depressions to even out the seams. Most of these require at least an hour to a day to completely dry before you sand. If you start sanding a puttied surface before it's dry, it will gum up your stick. If it simply sands off as a powder, it's completely dry.

 

You can wet sand, adding water to the surface. This helps lessen the scratches made during sanding. Wet sanding is also a way to make the grit you're using "finer" than it is because of the reduced friction (as using a "used" sanding stick also does compared to a new one). Wet sanding also produces a "slush" that can gum up indented panel lines and clog your sanding stick faster (though both wash off easily). Dry sanding produces a fine dust that gets into open areas of the model and that you might also breathe in. Slush or dust, it's your choice; and both of them may be used when and where it's convenient to you.

 

When you sand round parts (landing gear struts, gun barrels on tanks, missiles, etc.), you need to be careful not to overdo it and create a flat spot on a side. There's a product called the "FlexiFIle" (a U shaped handle with a strip of sandpaper) that's made for sanding round parts. The sanding strip flexes across the surface lessening the chances of overdoing it. I recommend getting one of these if you have the chance; or just be careful!

 

General surface sanding for "tooth", as Peter mentioned, may be needed depending on your paint of choice, especially if it's an acrylic. Enamels and lacquers grip the surface better because their solvents etch it into the surface, providing its own tooth. Acrylics need a rougher surface to grip onto, since they don't etch into the plastic.

 

Hope this helps!

 

GIL :smiley16:

Edited by ghodges

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