guide to wet sanding

[onnfire]

Is there any guide on how to wet sand correctly? What is it used for?

[Magic]

Re: guide to wet sanding

Originally posted by onnfire
Is there any guide on how to wet sand correctly? What is it used for?

Wet-sanding is usually performed to remove Orange Peel, and correcting defects that normal machine polishing won't remove.
I will say that Wet-sanding is to be considered the most extreme way of removing defects, and should not be attempted by novice detailer's. You could easily cause damage the finish, that only a re-paint will fix.

[Mike Phillips]

What are you working on?


There's a lot of confusion also over wet-sanding factory paint and the more common wet-sanding work which is done on fresh paint coming out of your local body shops.

Factory paint is baked as the car goes down the assembly line and by the time you take possession of the car it's fully set-up and this can make it difficult to get your sanding marks out of it.

You can easily sand any paint, that is put scratches into the paint in an effort to remove a defect, it's the removal part that gets tricky and sometimes difficult.


Here's an example of doing intricate sanding to remove the deepest of scratches after the lighter swirls and scratches were removed using a rotary buffer. Most people shouldn't undertake work like this without years of experience and even a few mistakes under their belt. What you're going to see below is a car I prepped one half of for display at the 2002 Bimmerfest to show what can be done with the right products and techniques.




Before

(Kind of hurts your eyes to look at)



Feather Sanding







After Drivers side only






Back for the other side after the show...




Completely Finished










Here it is on display at the 2002 Bimmerfest

[onnfire]

im not actually needing to wet sand anything. Im just trying to learn some about it. Would it be advised to try and learn on like another body panel. Does wet sanding involve the use of like 2000 or 2500 grit sandpaper or do you use a rotary?

[Mike Phillips]

Originally posted by onnfire
im not actually needing to wet sand anything. Im just trying to learn some about it. Would it be advised to try and learn on like another body panel.

Yes, go to the wrecking yard and purchase the hood or deck-lid off a car.

[onnfire]

Would it be best to learn how to use a rotary first?

[Mike Phillips]

Originally posted by onnfire
Would it be best to learn how to use a rotary first?

Yes, it will be neccassary to know how to use a rotery in order to remove sanding marks.

[TLMitchell]

Re: guide to wet sanding

I've been reading so many threads on wet sanding my eyes are about crossed. Still haven't run into the answer to my particular quizzical so I guess I'll stick it in this old thread and hope for the best...

Yes, go to the wrecking yard and purchase the hood or deck-lid off a car.

I did just that. I've got a few sheets of 2000/2500/3000 Unigrit and am going to try all sorts of things.

My thoughts are on the reuseability of Unigrit from one short session to another. Is it reuseable? Should you keep it wet? Howzabout if it would happen to dry? When is it considered 'used up'?

Appreciate any pointers,

TL

[Mike Phillips]

Re: guide to wet sanding

My thoughts are on the reuse-ability of Unigrit from one short session to another. Is it reusable? Should you keep it wet? Howzabout if it would happen to dry? When is it considered 'used up'?

Appreciate any pointers,

TL

You can use a sheet of sanding paper until it's worn down to where it's no longer effective for removing material. The best way to know when you've reached the end of usability for a sheet of paper is from experience as you can feel when the paper is no longer cutting well.

When you start with a new piece of paper note in your mind how it drags across the paint, this drag is the cutting action. As the paper wears out it looses cutting ability and you won't feel this cutting dray any longer.

You can also test by sanding in an un-sanded area or a few strokes and then check the results, if you see the paint is hardly sanded at all then this tells you the paper is spent as it's no longer leaving a pronounced saning mark pattern.

You can also watch for the amount of material, (that's the paint), you see accumulating in the water as your sanding, that is with a fresh piece of sandpaper you'll see a lot of material in the puddles of water on the panel as you're sanding. With a clear coat this will look like milky water. It's most pronounced when you first start out as that's when the paper is cutting best, as the paper wears you'll see less material coming off and accumulating in the water.

This is kind of hard though if you're continually adding fresh water to the sanding process so it's not a great indicator.

Mostly get some hours behind your backing pad by sanding and focus on the task at hand.

Note the higher grits like #2500 and #3000 don't offer dramatic cutting action to start with so it gets harder to tell when they are wearing out.

The paper backing for our Nikken brand papers is a rubber/latex type of paper and it won't break down in water. I lost a plastic container filled with water and Nikken papers for over 2 years and when I finally found it the papers were still perfect and ready to be used. Get a Grit Guard for your wet-sanding bucket to trap paint and grit particles on the bottom of the bucket and this will help to prevent tracers.

Keep your papers in your wet-sanding bucket until they are spent, then throw them away.

[TLMitchell]

Re: guide to wet sanding

(snipped it all)

Thanks for the info, Mike. Especially appreciate you taking the time on the weekend. As usual, excellent info!

TL