Found considerably more blisters this fall haulout and figure it is time to barier coat. The yard guy at our club recomended using an eight inch angle sander to sand the hull to the gelcoat. While I can find big angle grinder I havegot a feeling that they aregoing to be spinning to fast for sanding. My question is how fast should this setup be spinning to sand efficently, while minimizing the chance of burning through? Thanks.
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7" vari-speed
There are power tools (angle grinders) that are vari-speed and have the standard 5/8"-11 thread which a 8" disk fits over a 7" backing plate and works great! The one I use is a Chinese brand, which works fine but I'm sure there are other brands out there. BTW buy your disks in bulk from an industral supplier. They'll be a little less exspensive.
There are power tools (angle grinders) that are vari-speed and have the standard 5/8"-11 thread which a 8" disk fits over a 7" backing plate and works great! The one I use is a Chinese brand, which works fine but I'm sure there are other brands out there. BTW buy your disks in bulk from an industral supplier. They'll be a little less exspensive.
Only a decent orbital!
A circular machine at any speed is okay for digging into blisters but can easily make a mess of sanding a hull. A gelcoat planer would probably be better and faster. An orbital sander, however, is the tool of choice with fiberglass. It can peel an apple and is almost incapable of doing the kind of damage you fear. If you want a smooth, careful job go with a quality 6" or 7" variable-speed, random-orbital sander with vacuum attachment; use 40-60 grit paper. Take safety and eco precautions like a bunny suit, gloves, quality respirator, eyeglasses, and groundcloth. Buy or rent industrial brands like Fein, Porter-Cable or DeWalt, ones you won't find at hardware stores. Rig a water-trap bucket if you want to protect your shopvac bearings. Don't use sandblasting, it pits the surface too much. Give the hull time to dry out before you do the barrier and wait for perfect conditions to avoid eventual bonding failures.
A circular machine at any speed is okay for digging into blisters but can easily make a mess of sanding a hull. A gelcoat planer would probably be better and faster. An orbital sander, however, is the tool of choice with fiberglass. It can peel an apple and is almost incapable of doing the kind of damage you fear. If you want a smooth, careful job go with a quality 6" or 7" variable-speed, random-orbital sander with vacuum attachment; use 40-60 grit paper. Take safety and eco precautions like a bunny suit, gloves, quality respirator, eyeglasses, and groundcloth. Buy or rent industrial brands like Fein, Porter-Cable or DeWalt, ones you won't find at hardware stores. Rig a water-trap bucket if you want to protect your shopvac bearings. Don't use sandblasting, it pits the surface too much. Give the hull time to dry out before you do the barrier and wait for perfect conditions to avoid eventual bonding failures.
something else to consider
I had my bottom sand blasted. The sand blasting removes 99% of the bottom paint and opens up tiny blisters you may not have seen if you just sand the bottom. The sand blasting was not cheap but I think it was well worth it. I also have a steel keel which was sand blasted also. I barrier coated the keel immediately after sand blasting and then touched up the hull cleaned out all the blisters and filled them with westsytem. Jim
I had my bottom sand blasted. The sand blasting removes 99% of the bottom paint and opens up tiny blisters you may not have seen if you just sand the bottom. The sand blasting was not cheap but I think it was well worth it. I also have a steel keel which was sand blasted also. I barrier coated the keel immediately after sand blasting and then touched up the hull cleaned out all the blisters and filled them with westsytem. Jim
Ditto John D.
Morning John: I've got to go along with John D. on this one. Unless you are real professional in the use of an angle grinder, I think you'll be better off with a random orbit, they are almost idiot proof. They are not as fast as a grinder, but that is the point, you'll be less likely to take off too much or create gouges that will require repair before painting. I have a set up similar to John D., and they are not that expensive nor as destructive as a grinder. Luck!
Morning John: I've got to go along with John D. on this one. Unless you are real professional in the use of an angle grinder, I think you'll be better off with a random orbit, they are almost idiot proof. They are not as fast as a grinder, but that is the point, you'll be less likely to take off too much or create gouges that will require repair before painting. I have a set up similar to John D., and they are not that expensive nor as destructive as a grinder. Luck!
I was a stripper
took multiple layers of paint off down to gel on a 37. Did a few hours with rented high quality orbital with 40 grit hooked to shop vac. Was taking about 1/2 hour per square root. Tool was heavy, loud and ineffective. Went to harware store stripper at about $15 -20 a gal, Used a 4" scaper with corners ground down and a 18" handle so I could get both hands on it. Took about 30 hours to strip bottom. I stripped a few dime sized areas out of the gell, but not a concern if you are doing a blister repair and barrier coat. The yard offered to spay on a stripper for about $500 (scraping not included) if I got tired of painting it on.
took multiple layers of paint off down to gel on a 37. Did a few hours with rented high quality orbital with 40 grit hooked to shop vac. Was taking about 1/2 hour per square root. Tool was heavy, loud and ineffective. Went to harware store stripper at about $15 -20 a gal, Used a 4" scaper with corners ground down and a 18" handle so I could get both hands on it. Took about 30 hours to strip bottom. I stripped a few dime sized areas out of the gell, but not a concern if you are doing a blister repair and barrier coat. The yard offered to spay on a stripper for about $500 (scraping not included) if I got tired of painting it on.
Gel stripper is the way to go
You avoid the dust problem, tents, gas masks, heat, etc. Roll it on, let it sit, scrape it off, wipe the scraper into a bucket. I made a big heavy plexiglass scraper with slightly rounded corners. Wood works too. I put an old carpet under the boat and roll it up when I am done and throw it away when it dries out. Carpet stores will gladly give them to you.
You avoid the dust problem, tents, gas masks, heat, etc. Roll it on, let it sit, scrape it off, wipe the scraper into a bucket. I made a big heavy plexiglass scraper with slightly rounded corners. Wood works too. I put an old carpet under the boat and roll it up when I am done and throw it away when it dries out. Carpet stores will gladly give them to you.
Striiper??
Scott, were you really a stripper? Gross! So, how does a stripper chemical help with a boat with blisters? A boat with blisters is tough to scrape since the blisters get in the way. Also a stripper will not get rid of the blisters. I guess I don't see how anything other than a mechanical process (sanding or grinding) can do the job being discussed. What am I missing here? Randy
Scott, were you really a stripper? Gross! So, how does a stripper chemical help with a boat with blisters? A boat with blisters is tough to scrape since the blisters get in the way. Also a stripper will not get rid of the blisters. I guess I don't see how anything other than a mechanical process (sanding or grinding) can do the job being discussed. What am I missing here? Randy
Scot, Randy is right
I just did not want to say it first. I will not hesitate to pile on now. Randy, to get the blisters, you have to remove the bottom paint. Gel stripper is my preferred method for that part of the operation. You are right that you eventually need to grind out, dry out, and fill in the blisters.
I just did not want to say it first. I will not hesitate to pile on now. Randy, to get the blisters, you have to remove the bottom paint. Gel stripper is my preferred method for that part of the operation. You are right that you eventually need to grind out, dry out, and fill in the blisters.
A good stripper
Any particular brands of stripper out there that seem to work better than others?
Any particular brands of stripper out there that seem to work better than others?
A good stripper is a cheap stripper
just get the paste type by the gallon at Home Depot type stores. Randy makes a good point. Probably hard to scrape when bumping over blisters. I used chem strip w/o blisters present. Probably need to grind/sand out blisters before taking all the paint off. I have no blister experience. But a barrier coat requires removal of all paint. Chem strip with a acetone washdown got all the paint off for me.
just get the paste type by the gallon at Home Depot type stores. Randy makes a good point. Probably hard to scrape when bumping over blisters. I used chem strip w/o blisters present. Probably need to grind/sand out blisters before taking all the paint off. I have no blister experience. But a barrier coat requires removal of all paint. Chem strip with a acetone washdown got all the paint off for me.
Bottom Strip
An unbelievable product that I used to strip all the bottom pain at once with no scraping/no hard sanding was PEEL AWAY. Get it at Home Depot, not the boat store, its half the cost. Put down plastic on the ground, put it on following the directions and go home for the night. When you get back the next morning, be prepared to see some of the stripped paint on the plastic. For the rest take a three or four inch putty knife to release the paint and paper from the bottom to the plastic. Roll up plastic and put it in the trash. Rinse bottom off, let it dry and then sand with 80 grit. Wash with simple green. Afterwards, finish the bottom any way you want. Including grinding out blisters, barrier coat and/or bottom paint. I've used this twice, worked great for me. Good luck. Paul
An unbelievable product that I used to strip all the bottom pain at once with no scraping/no hard sanding was PEEL AWAY. Get it at Home Depot, not the boat store, its half the cost. Put down plastic on the ground, put it on following the directions and go home for the night. When you get back the next morning, be prepared to see some of the stripped paint on the plastic. For the rest take a three or four inch putty knife to release the paint and paper from the bottom to the plastic. Roll up plastic and put it in the trash. Rinse bottom off, let it dry and then sand with 80 grit. Wash with simple green. Afterwards, finish the bottom any way you want. Including grinding out blisters, barrier coat and/or bottom paint. I've used this twice, worked great for me. Good luck. Paul
Oh great.
So I'm supposed to walk into the Home Depot and when the girl at the paint desk asks what I am looking for I say "I'm looking for a cheap stripper." Then she decks me. I think I'll go the orbital sander route.
Randy
So I'm supposed to walk into the Home Depot and when the girl at the paint desk asks what I am looking for I say "I'm looking for a cheap stripper." Then she decks me. I think I'll go the orbital sander route.
Randymy mistake, John J
I had thought you were talking about a severe case of blisters, and taking the gelcoat off. Grinders, strippers and sandblasting are all unsuitable for this; you however were just talking about removing the paint, fixing blisters and applying barrier. Orbitals, strippers and VERY careful blasting are all good here. But change the sandpaper grit to 60-80 in my post.
I had thought you were talking about a severe case of blisters, and taking the gelcoat off. Grinders, strippers and sandblasting are all unsuitable for this; you however were just talking about removing the paint, fixing blisters and applying barrier. Orbitals, strippers and VERY careful blasting are all good here. But change the sandpaper grit to 60-80 in my post.
Be advised!
One thing about strippers is if you have any epoxy under the paint, the stripper will desolve the surface of any epoxy, as well it'll ruin the finish on a gelcoat. But if your going to grinding out blisters, your going to be doing some fareing anyway. But, thought it was worth mentioning. Fair Winds~~~~
One thing about strippers is if you have any epoxy under the paint, the stripper will desolve the surface of any epoxy, as well it'll ruin the finish on a gelcoat. But if your going to grinding out blisters, your going to be doing some fareing anyway. But, thought it was worth mentioning. Fair Winds~~~~
and still more advice
You will have to sand all the gelcoat on the bottom anyway to provide tooth for the barrier coat. And if you are 'sandblasting' to remove paint, use one of the alternatives like the baking soda thing thats less aggressive.
You will have to sand all the gelcoat on the bottom anyway to provide tooth for the barrier coat. And if you are 'sandblasting' to remove paint, use one of the alternatives like the baking soda thing thats less aggressive.
Not
PEEL AWAY does not remove existing epoxy barrier coat. I know this because both the boats I used it on had Interlux 2000/2001 epoxy barrier coat. Good luck
PEEL AWAY does not remove existing epoxy barrier coat. I know this because both the boats I used it on had Interlux 2000/2001 epoxy barrier coat. Good luck
Confused, Paul
I didn't follow what you meant, Paul. You said stripping worked on both boats, yet you said both boats had an epoxy barrier coat and stripping doesn't work with epoxy. How did it work for you then? BR says it dissolves the surface of the epoxy and can ruin gel coat. How does this relate to what you said? Also, how do you know if the barrier coat is epoxy? My boat was used in salt water for 20 years up till now (fresh water). It appears to have years of paint build-up that I want to remove before putting her back in the water in April. Should I assume it has an epoxy barrier coat that can't be removed with a stripper and I have to use an orbital sander? Or can I get the stripper? *666
I didn't follow what you meant, Paul. You said stripping worked on both boats, yet you said both boats had an epoxy barrier coat and stripping doesn't work with epoxy. How did it work for you then? BR says it dissolves the surface of the epoxy and can ruin gel coat. How does this relate to what you said? Also, how do you know if the barrier coat is epoxy? My boat was used in salt water for 20 years up till now (fresh water). It appears to have years of paint build-up that I want to remove before putting her back in the water in April. Should I assume it has an epoxy barrier coat that can't be removed with a stripper and I have to use an orbital sander? Or can I get the stripper? *666
re: confused
Scott, I had an O'Day 35 that we had barrier coat put on when it was new (I have since learned how to do that myself). After ten years of Petit bottom paint I decided to strip the paint but wanted to leave the barrier coat in tact. So, I hunted around asked questions and finally the owner of the marina said he had used the Peel Away and liked the result. So, off to Home Depot I went, got five gallons and extra paper (a special paper that must be put on the stripper after it is spread on the bottom). I used a trowel with 1/8th of a tooth, spread the stripper evenly, put the paper on as I went and then I went home. Came back the next day and much of the paint, with the paper, had fallen off leaving that portion still moist. I scrubbed the bottom off, sanded and refreshed the barrier coat with two more coats. Put my bottom paint on and then went sailing. This was (on a 35') about a five day process overall, long days. The barrier coat was not harmed as far as I could tell. On red paint came off, not gray barrier coat. If you want to test it on gel coat, then test it, but I don't believe it hurts it, just my opinion. I don't know if you have barrier coat or not. If you have a really old boat probably not, if you do it is probably black. Some barrier coats are black, white and some gray. I also believe the label on the Peel Away says it will not harm epoxy. Regardless, you have to sand the bottom with #80 after removing the paint. Hope this helps. I stripped the paint, not the barrier coat. Good luck. Paul
Scott, I had an O'Day 35 that we had barrier coat put on when it was new (I have since learned how to do that myself). After ten years of Petit bottom paint I decided to strip the paint but wanted to leave the barrier coat in tact. So, I hunted around asked questions and finally the owner of the marina said he had used the Peel Away and liked the result. So, off to Home Depot I went, got five gallons and extra paper (a special paper that must be put on the stripper after it is spread on the bottom). I used a trowel with 1/8th of a tooth, spread the stripper evenly, put the paper on as I went and then I went home. Came back the next day and much of the paint, with the paper, had fallen off leaving that portion still moist. I scrubbed the bottom off, sanded and refreshed the barrier coat with two more coats. Put my bottom paint on and then went sailing. This was (on a 35') about a five day process overall, long days. The barrier coat was not harmed as far as I could tell. On red paint came off, not gray barrier coat. If you want to test it on gel coat, then test it, but I don't believe it hurts it, just my opinion. I don't know if you have barrier coat or not. If you have a really old boat probably not, if you do it is probably black. Some barrier coats are black, white and some gray. I also believe the label on the Peel Away says it will not harm epoxy. Regardless, you have to sand the bottom with #80 after removing the paint. Hope this helps. I stripped the paint, not the barrier coat. Good luck. Paul
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