Gelcoat Sanding

Rather than pencil marks I recommend 3M dry guide coat. Even when wet sanding.

Lane

guide coat is good for taking away orange peel or a spar bump, but pencil makes a much smaller mess -AND- if he uses guide coat, he'll have black lines on his wing forever, since it will wick down into any remaining crazing (unless he plans on sanding the crazing away entirely, but that may also mean sanding the gelcoat away entirely, depending on how severe it is).

The technique i am describing is only finish sanding. the pencil is there to show what section to sand in, and the chord-wise pencil line lets you know if you've removed enough material/ not missed spots as you sand spannwise..

-ND

On Saturday, March 26, 2016 at 6:51:18 AM UTC-4, wrote:
Rather than pencil marks I recommend 3M dry guide coat. Even when wet sanding.

Lane

A friend of mine in the auto body business turned me on to 3M Dry Guide Coat, and I'm a huge fan. Used to use leftover rattle can paint and/or pencil, but this stuff is much better. It goes on dry, gets down into the pinholes and crannies, and doesn't clog the paper when you sand (if anything, I think it's a lubricant). Plus, you can get it out with some mild solvent (like Prep Kleen). Note: That's for wet-sanding new paint to get rid of the orange peel or identify low spots etc. What Andy is talking about is different, since it's failed/failing gelcoat. FWIW.

agreed! i love guide coat too. it shows EVERYTHING, even bad sanding technique, or a dinged up block.

On Tuesday, March 29, 2016 at 4:50:16 PM UTC-4, Papa3 wrote:
A friend of mine in the auto body business turned me on to 3M Dry Guide Coat, and I'm a huge fan. Used to use leftover rattle can paint and/or pencil, but this stuff is much better. It goes on dry, gets down into the pinholes and crannies, and doesn't clog the paper when you sand (if anything, I think it's a lubricant). Plus, you can get it out with some mild solvent (like Prep Kleen). Note: That's for wet-sanding new paint to get rid of the orange peel or identify low spots etc. What Andy is talking about is different, since it's failed/failing gelcoat. FWIW.

On Tuesday, March 29, 2016 at 2:07:12 PM UTC-7, ND wrote:
agreed! i love guide coat too. it shows EVERYTHING, even bad sanding technique, or a dinged up block.

On Tuesday, March 29, 2016 at 4:50:16 PM UTC-4, Papa3 wrote:
A friend of mine in the auto body business turned me on to 3M Dry Guide Coat, and I'm a huge fan. Used to use leftover rattle can paint and/or pencil, but this stuff is much better. It goes on dry, gets down into the pinholes and crannies, and doesn't clog the paper when you sand (if anything, I think it's a lubricant). Plus, you can get it out with some mild solvent (like Prep Kleen). Note: That's for wet-sanding new paint to get rid of the orange peel or identify low spots etc. What Andy is talking about is different, since it's failed/failing gelcoat. FWIW.

Check this out (I also posted on the Trizact thread):

https://www.youtube.com/watch?v=ke5kfYz9Ybw

On Thursday, March 31, 2016 at 12:19:48 AM UTC-4, 2G wrote:
On Tuesday, March 29, 2016 at 2:07:12 PM UTC-7, ND wrote:
agreed! i love guide coat too. it shows EVERYTHING, even bad sanding technique, or a dinged up block.

On Tuesday, March 29, 2016 at 4:50:16 PM UTC-4, Papa3 wrote:
A friend of mine in the auto body business turned me on to 3M Dry Guide Coat, and I'm a huge fan. Used to use leftover rattle can paint and/or pencil, but this stuff is much better. It goes on dry, gets down into the pinholes and crannies, and doesn't clog the paper when you sand (if anything, I think it's a lubricant). Plus, you can get it out with some mild solvent (like Prep Kleen). Note: That's for wet-sanding new paint to get rid of the orange peel or identify low spots etc. What Andy is talking about is different, since it's failed/failing gelcoat. FWIW.

Check this out (I also posted on the Trizact thread):

https://www.youtube.com/watch?v=ke5kfYz9Ybw

Note the sanding pattern demonstrated which is like what I was trying to describe above.
We use the 3M compounds and polishes for paint but use edge buffer applied hard wax/rouge for final buff and to impregnate/seal the gelcoat which has a lot of porosity.
UH