Reply
 
Thread Tools Search this Thread Display Modes
 
Old 06-27-2017, 09:47 AM   #1
Guru
 
Donna's Avatar
 
City: Palm Coast
Country: United States
Vessel Name: Southerly
Vessel Model: 1986 Marine Trader 36' Sundeck
Join Date: Aug 2016
Posts: 1,008
Dry sand or wet sand?

Recently had the gunnel, boot strip and bottom painted. After being forced into a piling and turned sideways at a very sub par marina, I need to sand a couple of small patches on my gunnel and repaint. Long story. My question is, should I dry sand these areas or wet sand them? I will be doing it by hand as it does not require a power sander.
__________________
Advertisement

Donna is offline   Reply With Quote
Old 06-27-2017, 10:36 AM   #2
Guru
 
alormaria's Avatar
 
City: Trenton
Country: USA
Join Date: Apr 2012
Posts: 1,102
I usually dry sand wood and wet sand metal.

Fiberglass I try not to sand - but when I do it's dry sand for the course grits and wet for the finer grits. Fiberglass I always seem to start out with a grinder so the decision is made for me. Wear rubber gloves and breathing protection. When you get fiberglass splinters use duct tape to pull them out. Don't take a hot shower until you do.
__________________

__________________
Al Johnson
34' Marine Trader
"Angelina"
alormaria is offline   Reply With Quote
Old 06-27-2017, 11:13 AM   #3
Guru
 
Donna's Avatar
 
City: Palm Coast
Country: United States
Vessel Name: Southerly
Vessel Model: 1986 Marine Trader 36' Sundeck
Join Date: Aug 2016
Posts: 1,008
Hmm, I'm not thinking the job is that big. My thought process is what would it really matter in the spot the size of my hand if I dry sanded and it happened to rain and I wanted to finish the sanding. Seems it has been raining everyday here and if I want to get some paint on it this would have to be done around 6am. That would give the paint several hours to dry and weather won't bother it at that point.
Donna is offline   Reply With Quote
Old 06-27-2017, 12:12 PM   #4
Guru
 
psneeld's Avatar
 
City: ACIW
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 19,113
Dry sand before fiberglass repair, wet sand after.
psneeld is online now   Reply With Quote
Old 06-27-2017, 12:30 PM   #5
Guru
 
jleonard's Avatar
 
Join Date: Jun 2008
Posts: 3,298
I would dry sand and then give it a quick acetone wipe just before painting.
__________________
Jay Leonard
Attitude Adjustment
40 Albin
Mystic,Ct. /New Port Richey,Fl
jleonard is offline   Reply With Quote
Old 06-27-2017, 12:48 PM   #6
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 15,660
Sorry to say it Jeff but acetone may destroy many finishes.

I'd use a much much less strong degresaer. I have found a solvent-like wash called the ultimate prep or something like that. It's specifically for cleaning while prepping for paint. I had (for decades) a very weak solvent called Doosol (Sp?) (Dupont). Got it to clean my varnished wood propeller on my UL aircraft. Mostly to wipe the bugs off but I didn't want to damage the varnish on the prop and I cleaned it frequently. Used it extensively as I found many uses for it .. including washing my hands.

What you use shouldn't flash off like acetone but should dry faster than automitive solvent. When I get home I'll send you the name of the perp wash.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 06-27-2017, 01:36 PM   #7
Guru
 
City: gulf coast
Country: pinellas
Join Date: Jun 2014
Posts: 2,712
Indeed many solvents will lift the remaining paint.
bayview is offline   Reply With Quote
Old 06-27-2017, 03:36 PM   #8
Guru
 
Seevee's Avatar
 
City: st pete
Country: usa
Vessel Model: 400 Mainship
Join Date: Sep 2016
Posts: 2,054
Quote:
Originally Posted by Donna View Post
Hmm, I'm not thinking the job is that big. My thought process is what would it really matter in the spot the size of my hand if I dry sanded and it happened to rain and I wanted to finish the sanding. Seems it has been raining everyday here and if I want to get some paint on it this would have to be done around 6am. That would give the paint several hours to dry and weather won't bother it at that point.
Al has it right, dry sand the courser stuff and wet sand the finer stuff, perhaps down to 500 grit.

Get yourself a supply of good sandpaper, from 80 or even courser) to 1200 for this stuff.

Assume you do not have gel coat? That's a bit different, but not hard.

And what kind of paint are you using? If you could get a sample color to your paint supplier and have them mix an exact color, you'd have it for all your touch up stuff.

And you can spray or brush most paints... even poly urethan paints, but requires a really high end brush and very light coats. Works well when spray painting is a PITA for small areas.
__________________
Seevee
Seevee is offline   Reply With Quote
Old 06-27-2017, 05:57 PM   #9
Guru
 
alormaria's Avatar
 
City: Trenton
Country: USA
Join Date: Apr 2012
Posts: 1,102
When it rains, just hold your hand over it until it stops.
__________________
Al Johnson
34' Marine Trader
"Angelina"
alormaria is offline   Reply With Quote
Old 06-28-2017, 10:04 AM   #10
Guru
 
City: Fairport
Country: United States
Join Date: Jan 2017
Posts: 1,502
Hard to talk with complete precision here, since we haven't seen the depth of the injury. But some general guidlines are useful.

Since this is a painted surface, avoid strong solvents. Very few paints will withstand direct acetone without softening. Denatured alcohol, mineral spirits, or the custom (wiping prep) work fine.

I'll assume you are dealing with cosmetic scratches. And, these will need filling. First off, get a 3M hand sanding pad; Bend and tear along a straitedge full sheets of sandpaper to fit. Without seeing the damage, I'd guess start with 120-150 grit dry paper to feather the damage into the good areas by an inch or two. So, at this point you are mostly removing good paint, and roughing the area of direct damage. Clean out the residue with alcohol. After a complete dry, you now need to fill the area with something sandable. That would NOT be marine tex or any other structural epoxy. For a fairly large job, I use West epoxy hand filled with sandable additives. For a tiny job, maybe like this, I would consider a surfacer putty or 3m Glazing putty. Interlux makes this, and I wouldn't even have a reservation using an AUTO putty. They dry fast and feather sand out nicely. Body shops use a ton of this stuff. Its fine above the waterline.
Once dry, attack with 180/220 grit until it won't catch a fingernail, then move to 440. It should be ready for touch up paint after that. Wet sanding is fine when using 220 or finer on metal or plastic. Its wood that will have grain rising issues when exposed to water.
Beyond all, remember the RULE: paints only change the color, it doesn't fill, smooth or make the surface non-wavy! It exploits all existing defects and makes its own! pinholes turn into volcanoes...
diver dave is online now   Reply With Quote
Old 06-28-2017, 10:37 AM   #11
Guru
 
Donna's Avatar
 
City: Palm Coast
Country: United States
Vessel Name: Southerly
Vessel Model: 1986 Marine Trader 36' Sundeck
Join Date: Aug 2016
Posts: 1,008
I was hoping for not a huge job. It is a few spots on the gunnell. I would like to feather it in. I have the exact paint already. It is Pettit E-Z Poxy self leveling. I have worked with this paint before. The point of even painting the gunnell was to change it from hidious blue to grand banks beige. I don't know why it was painted in the first place. I would have left it. Originally it was just white gelcoat. I just couldn't stand that blue.

So, I'm going to feather sand it, wipe it down with alcohol, roll a coat of paint on it and call it, "good enough" for now.
Donna is offline   Reply With Quote
Old 06-28-2017, 11:58 AM   #12
Guru
 
psneeld's Avatar
 
City: ACIW
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 19,113
Did you think the white to begin with was OK? Sanding down and re gel coating isnt much harder and better lasting than layers of paint.

But for touch up, a sime dry sanding is all thats needed. The fairing and final sanding to finish quality takes oatience and knowing whether you are leveling or polishing to a high gloss. The polishing is usually done wet.
psneeld is online now   Reply With Quote
Old 06-30-2017, 06:29 AM   #13
Guru
 
Donna's Avatar
 
City: Palm Coast
Country: United States
Vessel Name: Southerly
Vessel Model: 1986 Marine Trader 36' Sundeck
Join Date: Aug 2016
Posts: 1,008
Quote:
Originally Posted by psneeld View Post
Did you think the white to begin with was OK? Sanding down and re gel coating isnt much harder and better lasting than layers of paint.

But for touch up, a sime dry sanding is all thats needed. The fairing and final sanding to finish quality takes oatience and knowing whether you are leveling or polishing to a high gloss. The polishing is usually done wet.
The previous owner SPRAY painted the gunnell blue and didn't do a good job. There was over spray everywhere. Working on it today. It is the first thing I see when I walk up to the boat.
Donna is offline   Reply With Quote
Old 07-01-2017, 05:15 AM   #14
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 19,128
"Seems it has been raining everyday here"

In November it will dry out,
FF is online now   Reply With Quote
Old 07-01-2017, 05:17 AM   #15
Enigma
 
RT Firefly's Avatar
 
City: Slicker?
Country: Bumpkin?
Join Date: Oct 2007
Posts: 12,423
Greetings,
Ms. D. If you're trying to remove overspray, try some rubbing compound.
__________________

__________________
RTF
RT Firefly is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 07:44 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012