# wetsanding guide?



## tdimpreza (Apr 17, 2007)

Ive come across a few items of my own and some friends who have asked me to wetsand along with detailing but i always say no. 

I have no experience with wetsanding and to be honest on some request im plain scared to do even think about doing it.

So ive decided its now time to ask houw and find some practice panels and learn the art.

So can anyone lend themselves to provide a good guide or source of information on technique, materials, tips? 

(i searched "wetsand" but didnt come up with anything other than people have vandals and keyings)


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## haxbyscoobs (Dec 1, 2006)

scrap yard buy some front wings / bonnets etc


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## rubbishboy (May 6, 2006)

How about this one? http://www.detailingworld.co.uk/forum/showthread.php?t=49643


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## tdimpreza (Apr 17, 2007)

Thanks ! just like what i was looking for. its a good start.


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## Clark @ PB (Mar 1, 2006)

number one rule - make sure you soak the paper in a shampoo solution for a good few hours (i do mine over night if possible) to avoid leaving sanding marks, not only do these look crap but are a pain in the **** to remove!


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## L200 Steve (Oct 25, 2005)

Most of the traders on this forum sell Meguiar's Unigrit wet and dry papers in 2000, 2500 and 3000 grit grades. You should get away with only needing a couple of sheets of each to sand a full car.

Get yourself a decent high lubricated shampoo, something like Meguiar's #00 is my favourite for this purpose.

Mix yourself a small batch of the #00 mix up in a tupperware box 24hrs before doing any wet sanding. Mix the #00 64 parts water to 1 part shampoo. Put your sanding sheets into the solution and leave to soak and soften overnight. Mix up some more #00 and fill an old QD spray bottle with the solution.

Get yourself a backing pad for the hand sanding, Meguiar's do a nice foam strip for this purpose. This stops you from applying too much pressure in a confined area (not good)

Take a set of PTG readings on the area that you want to sand. You really need to be able to get a consistent reading every reading. Take note of this reading.

Starting with the finest paper first (3000 grit) wrap the soaked for 24hrs paper around the foam block and make five light passes in one direction over the area that you want to sand. I spray the area to be sanded with a couple of good sprays of the #00 solution from the spray bottle. Try and keep the paper as tight as possible to the block and try and keep the passes uniform. Keep the paper clean by spraying the sanding face with the spray bottle of soap solution often, and by spraying the work area often too (this removes the particles of clear that you are sanding off)

Dry the area (this is important as you'll blow most PTG's taking readings on wet surfaces) then take another couple of readings with the PTG. You should only have dulled the surface with the 3000 grit, but you will see how much paint you have removed. This will be very marginal, if any thickness at all.

Now polish out the 3000 grit marks with your rotary / PC / by hand using a polish like Menz IP 3.02.

Take another set of readings and record.

You will at this stage not have removed any real defects, but you will have a good idea of how much paint 3000 grit and IP 3.02 will remove.

I normally practice a 10% rule when working on defects. If the paint measures 100 microns consistent, then I'll remove 10 microns. If the area measures 150 microns in original paint, then I'll remove 15 microns. If the paint has been resprayed at any time, then I'll only remove 5 or 6 microns, regardless of how much is on there. (There might be a lot of paint in total thickness after a respray, but I have no way of telling how thick the clear coat is. OEM spray shops are a bit better at getting a consistent layer or two of clearcoat on than most aftermarket spray shops)

You should now be ready to do 5 passes with the 2500 grit. Same again, take 5 good slow passes over the area with the wet paper . Same as before, dry and take some PTG readings to see how much the 2500 grit has removed. If you are still well within the 10% rule, it should be safe to go over the area with the 2000 grit papers. Remember though, you'll need to go over the area you've 2000 gritted with the 2500 grit paper for a further 5 passes, then go over the 2500 gritted area with 3000 grit and then finally polish out the 3000 grit with the IP 3.02. By knowing how much paint is being removed at each stage by making 5 passes with the sanding paper will allow you to either fully remove the defect with the minimum of total paint thickness, or remove as much of the defect as you can within safe tolerance.

After getting comfortable with knowing exactly how much 5 passes of each grade of paper removes from your paintwork, you'll soon be able to start at the coarse 2000 grit papers and know exactly how many passes you can make safely.

FWIW I find that I often do 15 to 20 passes over a single area with the 2000 grit to remove a defect. 5 or 10 passes with the 2500 grit to remove the 2000 grit marks and then 5 or 10 passes over the area with 3000 grit to refine the finish before finally polishing out with 3.02 and still staying within my set 10% margin.

Try and stay an inch away from the edge of any panel. This is more to do with how difficult it can be to polish right to the very edge of some panels, than with the paint being thinner on edges. You'll soon learn how much harder it is to polish out sanding marks close to a shut line.

If you are going to sand a 6" square section on a panel to remove a defect using the 2000 grit, you need to sand a slightly larger area when going over it with the 2500 grit and slightly larger again when going over with the 3000 grit. This ensures that even the edges of your sanding repair are polishable. 

Most of all though, while learning the ropes, take your time and take many PTG readings. You'll soon learn that wet sanding isn't as hard or as daunting as it first looks, but it's made a lot safer using the many PTG readings recommended above.

That's how I do it:thumb:


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## rapidseven (Apr 26, 2007)

nice write up Steve, although soaking the paper in liquid for 24hrs makes no difference in performance than one soaked for 2 minutes, but thats with shop bought paper, not meguiars as ive never used it.


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## tdimpreza (Apr 17, 2007)

awesome write up, im looking around at different supplies and stuff (debating on what to try out first but i think i might give those megs a shot)


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## dubsport (Aug 25, 2007)

Good write up, always reassuring when u read these!

Think i will be taking a trip to the nearest scrap yard soon


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## Bigpikle (May 21, 2007)

Steve - can i just clarify what 5 passes in one direction means?

Do you mean one pass = back AND forth in one direction, or just one SINGLE swipe eg left to right and back again, OR just left to right?

thanks


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## Epoch (Jul 30, 2006)

One direction otherwise you can create deeper marks as you change direction

So push away (or pull towards) lift and reposition


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