Bottom Paint Prep

[jason3317]

My boat bottom is barrier coated and the anti-fouling is Micron Extra.

Interlux website says 'lightly sand and apply' to renew the anti-fouling. Exactly, what is meant by light sanding?

1. What grit?
2. Can an orbital sander be used, or is hand sanding with a block recommended?

What else do I need to know? The bottom appears to be in good condition (no chips in the paint, etc)....

Btw, I posted the same over to Anything-Sailing, so don't get too mad when you see my question there too.

Jason

[JimsCAL]

If the paint surface is in good shape, I wouldn't sand Micron as you will reduce the paint thickness and thus the anti-fouling life. Only sand to smooth the surface. A wipedown with thinner is all you need to do to prepare for a new coat.

[sailingdog]

Hand sanding with 80-100 grit should work just fine. You're just roughing the surface to give the new paint something to grip.

[sailingfool]

Originally Posted by jason3317

My boat bottom is barrier coated and the anti-fouling is Micron Extra.

Interlux website says 'lightly sand and apply' to renew the anti-fouling. Exactly, what is meant by light sanding?

1. What grit?
2. Can an orbital sander be used, or is hand sanding with a block recommended?

What else do I need to know? The bottom appears to be in good condition (no chips in the paint, etc)....

Btw, I posted the same over to Anything-Sailing, so don't get too mad when you see my question there too.

Jason

I think what you are asking is how to renew the paint prior to launch, without putting a new layer on...? I usually just launch, leave the paint alone, I assume the spray-washing after hauling leaves the bottom ready to go...subject to any necessary touchup, or a periodic additional coat as needed.

[jumaggafanny]

Ablative paint releases the compounds to the water over time. I think what you are asking about is sanding to expose new compounds. A light hand sanding with 100 grit to remove just a little of the oxidized surface and expose new "active" surface. It does remove some of the thickness but anti-fouling is a process that must be maintained. Recoating when you wear thru.
Good Luck Jason, try to keep it only partially submerged!

[sailingfool]

Originally Posted by jumaggafanny

Ablative paint releases the compounds to the water over time. I think what you are asking about is sanding to expose new compounds. A light hand sanding with 100 grit to remove just a little of the oxidized surface and expose new "active" surface. It does remove some of the thickness but anti-fouling is a process that must be maintained. Recoating when you wear thru.
Good Luck Jason, try to keep it only partially submerged!

Ablative paint IS "the compounds", it releases itself, leaving nothing behind. It does not oxidize. Most non-ablative paints have a binder of some type which builds over time. With ablative, if you pressure-wash the old scum off, it's ready to go. All any sanding does, is remove valuable and expensive paint.

[SailChick20]

Just to clarify...are you applying the same paint?
Make sure no compatability issues before applying.

[sailingdog]

Just curious—

Are you just trying to renew the paint and splash the boat or are you actually going to be painting the bottom?

[CalebD]

What SD said.
No paint? Leave it alone.
Painting a new coat? A light sanding followed by an application of a coat of paint.
Now I am really mad.

[jason3317]

Sorry, everyone, I was computerless yesterday. And, I didn't do a good job explaining my question.

I have ablative/self-polishing Micron Extra on the bottom currently. I am painting the bottom with Micron 66 on top of the Extra.

Intexlux compatability chart says 'sand lightly to a tightly adhered surface and paint' - they are compatible paints. So, I don't need to completely remove the old 'Extra' paint..

I'd like to use my random orbital sander to minmize the sanding effort. I am planning to lightly scuff up the paint with the orbital + 80 grit discs by moving quickly across the existing paint surface.

So,I know I need to sand 'lightly'. But, I am not sure what lightly means?