How long will a half sheet of wet/dry sandpaper last?

How long will a half sheet of wet/dry sandpaper last before it stops cutting and you need to replace it?


As for how long a single sheet of paper will last there is no hard answer, different brands will vary in how long they will last due to their physical make-up of both backing material, adhesive and grit dispersion.

Most of my experience is of course with the Nikken Finishing papers because it just makes so much sense to use them when the goal is to leave as much paint on the car during the process.

Keep in mind, as shown in the pictures in the above thread, there are two common ways to wrap your paper around a backing pad for hand sanding, neither allow you to use 100% of the sheet of paper but instead you're folding the paper in such a way that the usable area matches the surface area of the actual face of the backing pad. (Click the link and look at the pictures and the last sentence will make perfect sense).


Wet-Sanding by Hand
So with all of the above said, and assuming you're asking specifically about wet-sanding by hand, then here's what I do, I rely on my sense of touch and vision to gauge when the paper has reached the end of it's working life. This requires a few things, one is a person has to do a lot of sanding so they can get experience. Sanding down something like a Suburban is a good start and that's the first vehicle I did a complete sand and buff job on back in about 1990, were talking about a lot of real-estate and luckily most of the panels are fairly flat and basic so that makes it a lot easier to work on.


Monitor paper drag as affected by cutting effectiveness
Then as you're sanding, and this is key, focus on the task at hand. I know that sounds so basic but it's vitally important especially if it's not your car you're sanding. By focusing on the task at hand this means you're using your sense of touch to gauge the drag of the sandpaper against the paint. When using a brand new sheet of sandpaper you will feel the most drag as the abrasive particles cut into the paint. The more you sand the more the particles will wear down and even come off the paper and the level of drag or cut will decrease. It's your job to sense the change as you sand.


Monitor paint residue coming off the panel.
As you sand, you need to look at the water/paint solution on the surface. You can see the paint particles you've removed suspended in water on the surface of the section you're sanding and when a paper is new you will see more paint suspended in the water than you will as the paper wears out.

If you're working on a clear coat the water will have an opaque, milky look to it. If you're working on a single stage paint you'll see the color of the paint in your water solution only it will be harder to see because it will match the panel you're working on.

Using both your sense of touch and your eyesight, that's how you gauge when you're paper is cutting good or when it's cutting ability starts to fall off. As it falls off you'll need to decide when it's cost effective to either re-fold your paper to expose a fresh section, or if you used up the paper to the best of your ability to wrap it around your backing pad then switch to a new sheet of paper.

Trying to use a piece of paper for too long will result in the sanding process to take longer as the paper will remove less paint with each stroke. Tracer problems tend to increase as the paper wears out also.

That's how I've always gauged my papers, (sense of touch and visually looking at the paint suspended in water). It's not a perfect system but when it comes to hand sanding there's not a lot of great methods to gauge the fall off of your paper's efficiently.

Keep in mind you're sense of touch and looking at the section your sanding is real-time monitoring assuming your focusing on the task at hand and for big jobs that requires you focus on the task at hand because it's easy to get distracted and sand with your hand while looking somewhere else or thinking about something else.

If you want you could try to count strokes but that's not a very good system on a large project.

Another thing you can do is test your paper as you move to a new section, again you have be focusing on the task at hand and take a little time to squeegee the water off the panel and then inspect your progress and/or results. Testing works well if what you're doing is removing orange peel because you can sand for a few strokes and then squeegee the water off the section and then inspect and it will be real easy to see where any orange peel remains in the section you've sanded.

By this I mean, start out sanding a section about a foot squared or so and squeegee off the water and inspect the paint and remember or lock into your brain how long you sanded that area or approximately how many strokes you used to sand that section along with your downward pressure before stopping to squeegee off the water.

Once you've removed the orange peel and the section is flat to your expectations, move to a new section. Repeat the process and inspect the results by squeegeeing off the water. As your paper wears down, you'll notice that it's taking longer to remove the peel to get a flat looking uniform appearance. Again you'll have to make the decision to either keep sanding with the same sheet of paper or fold to a new side or replace the paper.


Doing a GREAT job of sanding a paint job flat is a lot of work and some would consider it an art form, I know I do.

Don't know if that helps you at all but that's about all I can share with how to gauge when your paper's cutting ability is falling off.

Nikken Finishing papers are a tad on the spendy side as compared to any basic wet/dry paper as they are a fairly high-tech paper. But keep in mind that whenever you're sanding paint you only have so much film-build you can safely remove and if you make a mistake because of lesser quality papers the cost of repainting a panel more than justifies the higher quality Nikken papers, not to mention the time involved in fixing a mistake and the fun of telling the owner of the car what happened. :)

Nikken Finishing papers were introduced to North America by Bill Stuart, the guy that owns and sells the Absorber. Bill was an Meguiar's RDC owner until Meguiar's bought all the RDC's and then he went his own way. At some point in the 1980's Bill sold his rights to sell the paper in North America to Meguiar's, that's how Meguiar's obtained distribution rights. Bill told me that the Nikken paper is actually an electronics grade paper and the quality control as such was much higher than an automotive grade paper. The Nikken papers used a latex impregnated paper for a backing so they won't and don't break down like lesser quality papers and instead of having grit particles dropped onto the paper during the manufacturing process, somehow an electrostatic charge is used to draw the particles up to the paper so the paper travels down the manufacturing process upside down.

Nikken Finishing papers offer Unigrit Particle Size and just as important, Uniform Particle Placement over the entire sheet of the paper whereas a traditional wet/dry paper is about a 60/40 fill with much less control over particle size of the grit.

Because of this, Nikken finishing papers offer sanding marks with a uniform depth and uniform sanding mark pattern over the paint being sanded. Note I didn't use the word scratches, as in a uniform depth and uniform sanding scratches because the quality of the paper tends to leave the paint just looking dull, not filled with sanding scratches.

The goal is enabling a person to remove the least amount of paint to get the job done, (that means more paint on the car for the customer over the service like of the car), while leaving a sanding mark pattern that will buff out faster and with more control on the side of the technician. If you use papers that have little or no control over the particle size or placement of particles on the face of the paper you lose control over the sanding marks and thus the technician looses control over the process.

Of course, given the chance I prefer to machine sand with an air powered DA Sander first and save hand sanding for areas that don't lend themselves well to machine sanding.


What's really cool is Autogeek offers people the ability to get a collection of different grits instead of having to purchase entire sleeves of a single grit.

Meguiar's Unigrit Sand Papers 8 Sheets - Your Choice!


For those of you on the East Coast that want to learn how to hand sand and wet-sand this will be one of the classes we will be offering.


Further Resources
Basic Hand Sanding Techniques
Wet-sanding - Fresh Paint vs Factory Paint
RIDS and Feathersanding - A Highly Specialized Technique by Mike Phillips
Removing Orange Peel & Sanding Marks with the Griot's ROP and the Wolfgang Twins


http://www.autogeekonline.net/forum/...lies/smile.gif

Need to print this. right now. everytime it's a new adventure, a new challenge.

thanks for sharing Mike.

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Originally Posted by zckid

Need to print this. right now. everytime it's a new adventure, a new challenge.

thanks for sharing Mike.

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No problemo... hope it helps...


:xyxthumbs:

Hey Mike, Im planning on repairing a key scratch this weekend. All I have for leveling the touch up paint is 3000 grit nikken sheets. Will that be sufficient?

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Originally Posted by BrianJM

Hey Mike, Im planning on repairing a key scratch this weekend.

All I have for leveling the touch up paint is 3000 grit nikken sheets.

Will that be sufficient?

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Yes. My tip for this type of work is to let the touch-up paint fully dry and harden before starting.


:)