Graphite paint questions

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fallguy1000
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Graphite paint questions

Post by fallguy1000 » Fri Jan 17, 2020 8:26 am

Thinking about doing some graphite paint.

My boat is beachable. The bottom of the beaching keel has a sacrificial timber. I plan to add an aluminum strip 1.5" wide.

I am a little nervous a high beach will damage the ablative paint forward.

Can I use the graphite paint for a wear layer forward? Will it chalk badly and how often does it need sanding and relayering from chalkout?

Pic coming later.


My boat build is here -------->

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terrulian
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Re: Graphite paint questions

Post by terrulian » Fri Jan 17, 2020 9:20 am

The graphite acts as a UV barrier, so epoxy/graphite will not deteriorate in the sun very much compared to unprotected epoxy. In addition, it is on the bottom and therefore has less UV exposure.
I'm a little confused about your mentioning of "ablative" paint, which I assume is anti-fouling. This is very soft and subject to abrasion, which will expose the graphite/epoxy and leave the abraded area subject to marine growth. However, anti-fouling is only necessary if you are keeping your boat in a slip or on a mooring. On a trailer it is not necessary.
Tony
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fallguy1000
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Re: Graphite paint questions

Post by fallguy1000 » Fri Jan 17, 2020 10:30 am

terrulian wrote:
Fri Jan 17, 2020 9:20 am
The graphite acts as a UV barrier, so epoxy/graphite will not deteriorate in the sun very much compared to unprotected epoxy. In addition, it is on the bottom and therefore has less UV exposure.
I'm a little confused about your mentioning of "ablative" paint, which I assume is anti-fouling. This is very soft and subject to abrasion, which will expose the graphite/epoxy and leave the abraded area subject to marine growth. However, anti-fouling is only necessary if you are keeping your boat in a slip or on a mooring. On a trailer it is not necessary.
This is a slipped boat. Beam is 16' 6".

Here is a picture of the bottom. If you look close; you can see the sacrificial keel timber. I am worried about sand grinding off my ablative up ahead of the keel.
31EADA4F-B04F-4717-AFEB-90A330A239CE.jpeg
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viewtopic.php?f=12&t=62495

terrulian
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Re: Graphite paint questions

Post by terrulian » Fri Jan 17, 2020 12:47 pm

What is the gray paint I'm seeing?
I'm not sure what the concern is about sanding the ablative paint; it's done every couple of years anyway for a bottom job.
As I'm not sure I am understanding the issue correctly, this may not be relevant, but, if I were doing this on a boat that lives in the water and will from time to time be beached, I'd look into a hard bottom paint, not an ablative, and then apply that over the graphite/epoxy. The latter will help protect the glass underneath, and the hard bottom paint will stand up to more abuse.
https://www.bottompaintstore.com/boat-b ... 13528.html
IF you decide to use this kind of paint, you will have to remove the ablative completely, as it will fall apart so that the paint on top of it will not adhere. This type of question is best answered by the actual manufacturer, as not all paints are compatible. I'd give them a call or send an email. They are normally interested in customers having a good experience.
When applying paint on top of epoxy/graphite, sand lightly to produce some tooth.
Tony
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fallguy1000
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Re: Graphite paint questions

Post by fallguy1000 » Fri Jan 17, 2020 3:55 pm

I am using Vivid.

I want to know how to use graphite and where.
My boat build is here -------->

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terrulian
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Re: Graphite paint questions

Post by terrulian » Fri Jan 17, 2020 6:49 pm

Here's what I'd do: fairing>primer>graphite>hard anti-fouling. You don't want graphite as the last coat as it will give you no anti-fouling protection. It's purely for abrasion. With tooth your antifouling will bond to it. I wouldn't see the argument for stopping the anti-fouling up forward and just having graphite.
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Re: Graphite paint questions

Post by fallguy1000 » Fri Jan 17, 2020 7:18 pm

terrulian wrote:
Fri Jan 17, 2020 6:49 pm
Here's what I'd do: fairing>primer>graphite>hard anti-fouling. You don't want graphite as the last coat as it will give you no anti-fouling protection. It's purely for abrasion. With tooth your antifouling will bond to it. I wouldn't see the argument for stopping the anti-fouling up forward and just having graphite.
Where is the graphite recipe and method?
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terrulian
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Re: Graphite paint questions

Post by terrulian » Fri Jan 17, 2020 8:16 pm

Here is Cracker Larry's method--he, rest his soul, was a bit of a guru around these here parts.
app.php/page/cracker-larrys-graphite-application-tips

It depends a bit on what graphite you buy. Some will require sifting with a kitchen flour sifter, but mine was fine as it came. You don't want any lumps. Some folks heated the epoxy a little to aid in the emulsion, but I didn't. I just mixed neat epoxy, stirred it as usual, and then slowly blended in the graphite until it was still viscous but quite black and a little grainy. It's not going to go on smoothly like paint so you may be a little disappointed in the look; however, it's on the bottom for only the fish to judge.
Image

I support your decision to add the sacrificial metal on the bottom of the keel, as that's what takes the worst beating. I used bronze but aluminum will also work.
Tony
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fallguy1000
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Re: Graphite paint questions

Post by fallguy1000 » Fri Jan 17, 2020 8:48 pm

terrulian wrote:
Fri Jan 17, 2020 8:16 pm
Here is Cracker Larry's method--he, rest his soul, was a bit of a guru around these here parts.
app.php/page/cracker-larrys-graphite-application-tips

It depends a bit on what graphite you buy. Some will require sifting with a kitchen flour sifter, but mine was fine as it came. You don't want any lumps. Some folks heated the epoxy a little to aid in the emulsion, but I didn't. I just mixed neat epoxy, stirred it as usual, and then slowly blended in the graphite until it was still viscous but quite black and a little grainy. It's not going to go on smoothly like paint so you may be a little disappointed in the look; however, it's on the bottom for only the fish to judge.
Image

I support your decision to add the sacrificial metal on the bottom of the keel, as that's what takes the worst beating. I used bronze but aluminum will also work.
Thank you!
My boat build is here -------->

viewtopic.php?f=12&t=62495

fallguy1000
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Re: Graphite paint questions

Post by fallguy1000 » Fri Jan 17, 2020 9:09 pm

I have to modify this approach a bit. I am painting basically a section of the keel, so the graphite would flow down or to the outside of the epoxy. Will that be a problem? Then I only have a day or two to finish it, so can I do like 3 coats green on green with fast epoxy?
My boat build is here -------->

viewtopic.php?f=12&t=62495

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