Bottom paint removal

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dmairspotter
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Bottom paint removal

Post by dmairspotter »

I recall a thread recommending a particular type of scraper for bottom paiint removal, but I can't find it.

I want to start getting the crud off the Dufour this winter, get a jump on next year.

Any recommendations?
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Tim
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Post by Tim »

Get this Bahco Carbide Scraper, or any similar scraper that uses carbide blades. Carbide makes all the difference.

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Mark.Wilme
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Post by Mark.Wilme »

I am using a similar scraper on Impeckable (actually picked mine up at the Ace Hardware store for $8.00). It probably doesn't have a carbide scraper (it may ..) - It works fine provided I keep it sharp witha flat file.

That and a rubbermaid 3" putty knife (Rubbermaid have nice handles and non flexy blades).

We also find the paint comes off easier if wetted first.
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Peter
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Post by Peter »

Go for the carbide. I used three double-blades for the whole job, and stripped the bottom, including sanding, in 12 hours (2 hour stints to spare the muscles).

It's a dirty dusty job anyway you do it, but the scrapped pieces are a lot easier to deal with than sanding dust.

I found that if you very slightly round the corners of the blade ... just a bit ... you'll avoid a lot of gouges in the gel coat. I rounded mine on a sanding disk.
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Rachel
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Re: Bottom paint removal

Post by Rachel »

I've got a carbide scraper question:

A friend with a 32-footer is going to take the bottom down to gelcoat before re-painting, and he was talking about sanding. I asked him if he'd tried a scraper, as I'd heard good things about them (specifically the carbide ones) here. He hadn't, but proceeded to borrow one from a yard mate and found that it worked pretty well.

So he bought one at a local hardware store today. They didn't have Bahco, but instead had a different brand. It's similar in style, with the long handle and the ball grip near the blade end.

It was only after getting it home that he noticed the blade was curved. At first it seemed like it might be a matter of sloppy cutting at the factory, but actually the part of the handle that's just above the blade is similarly curved. It did mention, in small print, something about being.... erm I can't remember, but something like convex ground.

Pardon the poor photo quality - all that was available was a cell phone camera.

Image

Here's the blade alone, next to a straight paper edge:

Image

Couple of questions then:

1) I assume he'd be better off exchanging for a straight one.... ? (I can see that the blade on the previously shown Bahco is straight.)

2) We're curious where someone would want to use a curved scraper? I mean, this wasn't a specialty woodworking kind of place, where they have blades with multiple specialty profiles; it was just the one carbide scraper model at a hardware store.

Thanks,
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Re: Bottom paint removal

Post by Hirilondë »

When using a hand surface plane the blade is very slightly convex. This is so that one doesn't dig the corners into the wood. If the scraper blade is just slightly convex as well, it might actually work quite well.
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Tim
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Re: Bottom paint removal

Post by Tim »

I've never used a scraper like that, so I don't know how it will work. It seems that it's pretty significantly curved, and therefore will reduce the effective bearing/scraping surface with each pass on the flat-ish surfaces that make up a boat bottom (yeah, boat bottoms are all curved, I know, but in a 2" wide strip each pass is pretty flat to a scraper blade).

However, the curved blade may help avoid the problem of digging into the material with a straight, square-cornered scraper, which does take a little care and practice/experience to efficiently avoid. So if I were him, I'd give it a try. Of course, even though the blade itself is convex, the corners are still sharp and severe, just like the straight blades, so I imagine digging in will still be a problem to be watched.

The curved blade would be most effective in severely curved portions of the bottom, like the turn of the bilge or any areas where the boat pinches together, say at the aft end or near a skeg, but probably less effective over 95% of the surface.

He might be able to find normal straight replacement blades that will fit that scraper too. It looks like it uses the same sort of blade clamp as scrapers like the Bahco and others (from what little I can tell in the photos).
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Rachel
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Re: Bottom paint removal

Post by Rachel »

Thanks for the input. My guess is that a straight scraper with the ends ground to a slight round (as Peter did) would probably work best, but since he's got this one (he's on an island so no easy access to stores) I guess he might as well try it.

I'm not sure if a straight blade would work in this handle because - although you can hardly see it - the "clamps" for the blade are cast in a curve too. So I'm thinking that perhaps the ends of a straight blade would not get enough support? One way to find out, I guess, but if it were me I'd probably just mail order the "right" one and keep them both. As you say, this one may work well at the turn of the bilge.

Thanks again. Having never seen one like this I thought I'd ask about it.

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Re: Bottom paint removal

Post by Mario G »

It might have to do with the fact I paint alot of cars but I scraped the bottom paint off my C-22 with a single edge razorblade and a cheap $1 holder in less then 5 hours. I'm also sure it was the original bottom paint and just powdered away. No heavy pushing so no gouging of the gel coat.

Image

the picture after is the bottom baby smooth
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Re: Bottom paint removal

Post by preserved_killick »

I used a curved blade scraper just like the one shown to remove the bottom paint on my A30 and found that it worked great. I quickly noticed that the scraper worked best when used up and down (toe rail to keel) rather than side to side. Also the angle of the handle was key. By keeping the handle parallel to the surface, the blade lay flatter and cut using nearly all the width of the blade.
Edge digs were rare, easy to avoid.
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Rachel
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Re: Bottom paint removal

Post by Rachel »

I passed that info along (he hasn't started the project yet).

Thanks!

Rachel
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Re: Bottom paint removal

Post by Zach »

Makita 9227CY - http://www.amazon.com/Makita-9227CY-Var ... 457&sr=1-1

A soft pad for sticky paper...

Norton Blue Mag sandpaper. Or reasonably sticky equivalent.

The Makita is a variable speed... constant speed... sander. Meaning that when you set it to whatever RPM, it doesn't drag down as much as a normal grinder. Speed is set so the bottom paint isn't melting, and the adhesive isn't being cooked off. (Denatured alcohol takes the goo off, without melting the foam... like acetone does. Oops.)


You... are... so... beautiful. Grin. Just buy one. They are real light weight but will do the same work as a full size 7 inch grinder.

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