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wet sanding question

Posted By: papayamon2

wet sanding question - 12/21/06 11:51 PM

Hi everyone! In my continuing restoration project of an old Trac 14, I'm trying to get the hulls to shine once again. So far I've wet sanded them all w/ 600 grit paper to take out some flaws and clean them up, but I'm wondering how many more iterations of wet sanding are needed? Should I go 1000 then 2000, then buff? Or what? Can I go straight to the 2000 w/out the 1000?

Thanks, and my wife will be glad when this is finally done!
Posted By: Seeker

Re: wet sanding question - 12/22/06 12:03 AM

I go 400/600/1000/1500/"buff magic"(compound)with very good results.

Regards,
Bob
Posted By: catman

Re: wet sanding question - 12/22/06 05:34 AM

600 grit will buff fine. Anymore than 1000 is wasting your time.

Use an aggressive compound first then an Glazing compound to finish.
Posted By: Jalani

Re: wet sanding question - 12/22/06 10:06 AM

When I've repaired GRP in the past I've always gone 400/600/800/1200 and finished off with G6 cutting compound (fine). For dark colours you sometimes need to follow up with G10. Then buffed with a good quality wax. The results are invariably as good as new.

[Linked Image]

Attached picture 93995-yellowhammer.JPG
Posted By: Mark P

Re: wet sanding question - 12/22/06 10:59 AM

Yellow and black striped hulls, must have been bees wax <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
Posted By: scooby_simon

Re: wet sanding question - 12/22/06 11:54 AM

Quote
When I've repaired GRP in the past I've always gone 400/600/800/1200 and finished off with G6 cutting compound (fine). For dark colours you sometimes need to follow up with G10. Then buffed with a good quality wax. The results are invariably as good as new.

[Linked Image]


Hey, John, that looks like an old Condor !
Posted By: Jalani

Re: wet sanding question - 12/22/06 12:56 PM

Quote
Hey, John, that looks like an old Condor !


At the time (1978) it was quite a NEW Condor! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

So what was the giveaway? - The 'Condor 1978' sticker on the transom? <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

I think it was about 2-3 years old, we'd had a bit of an accident with it and ripped a big chunk out of the stbd hull bottom. The reason for the photo was that I was rather chuffed with the finished repair. Using Jake's 8'/ 5'/ 2' repair standard, it was about a 2" standard of repair! <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />
Posted By: Jake

Re: wet sanding question - 12/22/06 01:36 PM

Quote
600 grit will buff fine. Anymore than 1000 is wasting your time.

Use an aggressive compound first then an Glazing compound to finish.


I've had trouble getting a 600 grit finished followed buffing to sustain a shine longer than a month or so with the Team Seacats blue N20. I'm going to go up a level with the sanding and try buffing again.
Posted By: KenReid

Re: wet sanding question - 12/22/06 08:40 PM

Hi group,
I just polished up my new to me 94 Hobie 20 hulls to look like new. On one hull I first used 600,then 3M rubbing compound with a buffer(not orbital) and then I buffed with 3M marine fiberglass cleaner/wax.I used lambs wool pads. On the other hull I just went right to the cleaner/wax. I can not tell them apart.
Happy holidays
Ken
Posted By: papayamon2

Re: wet sanding question - 12/22/06 09:04 PM

I thought all buffers were orbital (my lack of experience!) I do have a buffer, but it's orbital. Does that matter?
Posted By: fin.

Re: wet sanding question - 12/22/06 10:29 PM

If it were not orbital, it would cut like a grinder so you're MUCH better off.

For future reference, the lighter the color the easier to clean and polish. So, if you have a choice. . .
Posted By: papayamon2

Re: wet sanding question - 12/23/06 01:54 AM

Looks like I'm set, then--my hulls are white!
Posted By: catman

Re: wet sanding question - 12/23/06 01:59 AM

Orbital won't do it. You need a polishing buffer. If you go out to buy one be careful you don't wind up with a grinder. They look similar.
Posted By: papayamon2

Re: wet sanding question - 12/23/06 03:05 AM

Hmm, my buffer says on the label: 10" Polisher, but it's definitely orbital. ??? What sort of motion does the one you're talking about have?
Posted By: Jake

Re: wet sanding question - 12/23/06 03:35 AM

to do real polishing, like catman says, it should look like a side angle grinder but with a rubber head, pad, and wool cover. If you were to leave this one running over one place too long, it will do damage. Should look like this (I've never seen one with a random orbit)

[Linked Image]


A random orbiting buffer (the kind that you find in the automotive section at walmart that mostly vibrates) will do a good job applying wax, but it will not work with rubbing compounds very well at all.
Posted By: papayamon2

Re: wet sanding question - 12/23/06 03:52 AM

Hey, who told YOU where I bought my polisher? <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />
Posted By: catman

Re: wet sanding question - 12/23/06 02:12 PM

I have a Dewalt 849 var. speed. Got it from a local auto paint supply, $100. Use a wool bonnet with the aggressive compound and a foam bonnet with the glazing compound.

Since your local, if you haven't already, you should go down to Fiberglass Coatings in St. Pete. They're on 19 just before 38th ave on left. They have everything you would ever need and are very helpful.
Posted By: Seeker

Re: wet sanding question - 12/23/06 02:59 PM

The best pads for the polishers are one piece...they thread right on to the standard 5/8" shaft of the polisher (which all serious polishers share)...they don't have strap on bonnets or rubber backing pads...they are about $18.00-$20.00

Here is what the manufactures rep for "Buff Magic" wrote me...

Our Buff Magic is used extensively by many boat manufacturers for polishing sanded gelcoat for repairs during the production process. All gelcoat sprayed after the fact of being pulled from the mold is sanded, and orange peel is unavoidable, so if yours is slight, you are to be commended on your application skills. Buffing from 400 is not recommended, nor is it a common grit to start buffing from. Most manufacturers buff at a minimum of P600 or finer. And for large areas such as an entire hull, you will highly benefit from going finer, such as P800 or P1000. The time and effort in sanding to a finer grit will save buffing time tenfold compared to the extra time sanding. Using only 400 grit will leave too coarse of scratches requiring much more buffing time and effort, and also will require multiple applications to remove all of the scratches. Multiple applications in addition to being time consuming will degrade the gelcoat beyond what is necessary, and also generates a lot more "heat" which can shrink the gelcoat, and create irregularities, and can cause a "print through effect" of the fiberglass behind the gelcoat. Additionally it is much easier to produce gloss when buffing finer scratches such as P800 or P1000. Buff Magic will work effectively from P600 and finer, but for your application to large areas, P800 or P1000 is recommended.

Jason Brennan
OEM Account Representative
Posted By: papayamon2

Re: wet sanding question - 12/31/06 11:26 AM

So I finally got around to spending half a day (!!) polishing my hulls. I ended up going 600/1000/1500 on the wet sanding and then polished with a 3M rubbing compound & wax restoration product. I tried polishing from 1000 but wasn't happy with the results, but the 1500 worked great. Very pleased, if I can just keep 'em looking like they do now. Which leads to my next question...

What is a good product to wipe on to keep and protect my hulls so they stay nice and, more importantly, so I don't have to spend another day of my life polishing?
Posted By: Jake

Re: wet sanding question - 12/31/06 01:58 PM

If the polishing job was effective, the shine will hold up well over time. If it wasn't terribly effective, the shine you are seeing is probably more the waxes, oils, and/or fillers that are in the rubbing compound. This is what I'm experiencing with the Team Seacats N20 and why the shine isn't holding up (since I stopped at 600 grit before buffing)

I've had really good results with NuFinish liquid wax - or any of the modern waxes that have UV inhibitors in them. My F18 gets at least two coats a year and it is holding up very well.
Posted By: PTP

Re: wet sanding question - 12/31/06 02:13 PM

Jake,
what happened to the preferred vertglass?
Posted By: tshan

Re: wet sanding question - 12/31/06 04:22 PM

Ditto on the NuFinish. Works like a champ.

A couple other questions:

1. Do you guys stick to the same routine (grades of sanding, buffing, polishing) when preparing daggerboards and rudders?

2. On my new boat, I've hand buffed and polished it - but have not done any sanding/heavy duty buffing. The finish seems to be nice. When should one consider a complete makeover? Depends on the wear and tear, I'd assume.
Posted By: Jake

Re: wet sanding question - 12/31/06 05:20 PM

Quote
Jake,
what happened to the preferred vertglass?


I dunno - I guess I haven't gone that route with the cat simply because I plan on redoing some gelcoat and removing the vertglas can be involved.
Posted By: tback

Re: wet sanding question - 01/05/07 08:43 PM

When one does wet-sanding do you always perform this task by hand sanding? Or use an electric sander until you get to a certain (fine) grade paper?
Posted By: bvining

Re: wet sanding question - 01/05/07 09:01 PM

I wouldnt wet sand with electricity - water plus electricity is bad mojo. I dont know of any waterproof sanders and wouldnt trust them if they did exist. Wet sanding requires you dunking the sandpaper into fresh water to keep the paper fresh, or by running water over the surface you are sanding. Either way, you need more water than would be safe around electricity.

If you asking - Can I dry sand up to a certain grit and then wet sand? Then the answer is yes, that works fine. Keep in mind that wet sanding keeps the paper free from clogging and keeps the paper fresh, so in my experience it actually works quite fast and "feels" like you are removing more material than a comparable grit dry sand.

But whatever you do, dont try to wet sand with an electric sander.

Bill
Posted By: tshan

Re: wet sanding question - 01/05/07 09:09 PM

Hmmmm, sounds like some one is getting ready for Tradewinds. No pulling any of these fancy tricks.....
Posted By: tback

Re: wet sanding question - 01/05/07 09:54 PM

Actually, my question was more geared around the thread of SportMax boxes and got me thinking about building a 'glass box (as descibed on that thread.)

As for Tradewinds, I do have some repair to my daggerboards from sailing last week in shallow waters. Seems like I'm building up my daggerboards about every other month.

...but no Tom ... no tricks from me. I'll be busy keeping my mainsail and spi' dry <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> and watching your sailing tactics from far behind.
Posted By: Jake

Re: wet sanding question - 01/05/07 11:46 PM

Actually pneumatic sanders are often employed for wet sanding. However, it really goes so quickly that you don't need the power and you'll find that you need the extra personal control with a simple foam block.
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