removing bottom paint
- Thread starter Tom M
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When it comes to bottom paint use the following formula:
Easy = Expensive (sodablasting)
Moderate = Moderate (chemical stripping)
Hard = Cheap (carbide scraper, sander)
IOW, the easier you want it to be, the more expensive it will be.
I have done 2 boats the hard way. The third, and present boat, I rented a sand blaster and used walnut shells. I still had to sand though. It cost about $300 and 1 1/2 days.
Easy = Expensive (sodablasting)
Moderate = Moderate (chemical stripping)
Hard = Cheap (carbide scraper, sander)
IOW, the easier you want it to be, the more expensive it will be.
I have done 2 boats the hard way. The third, and present boat, I rented a sand blaster and used walnut shells. I still had to sand though. It cost about $300 and 1 1/2 days.
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How big is your boat?
Answer may depend on size. On our 19' boat, i did this job last year, right down to gelcoat, and I tried several methods including sanding/scraping, but the best results came from using non-toxic soy-based strippers like Boat-Brite or SoyStrip. Least effort, no fumes, no harm to gelcoat, reasonable cost, water cleanup.
i am working on my 30 ft s2 and am useing a carbide scraper to remove to old bottom paint down to the gel coat an it is working just fine actually better than i expected...the key here is to pace your self and dont try to eat the elephant all at once ...obtw ware a filter mask of some sort ...the old paint gets in your mouth and leaves an after taste ugggggggggggggg
regards
woody
regards
woody
Paint Stripper
I had good luck using a marine paint stripper by Sea Hawk. I had several layers that it took off after leaving it on there all day. If you decide to use a paint stripper, the trick is to make sure that it stays wet.
I had good luck using a marine paint stripper by Sea Hawk. I had several layers that it took off after leaving it on there all day. If you decide to use a paint stripper, the trick is to make sure that it stays wet.
The easy way is to have a boat yard do it for you. All you have to do is write out the check or sign the credit card slip. No inhaling of toxic dust, you won't look like a Smurfette when done and you won't have to worry about bad stuff on the ground. Might be more money, but it is easy and easy is what you wanted.
As I have said before...all those "soy" and "orange" products are marketing ploys. Read the MSDS to see what you are really getting yourself into. I couldn't find one for the boat brite stuff and the soy stuff omits the active on the MSDS (not very nice of them). Both probably contain a pyrrolidone, probably NMP, which is a suspected reproductive toxin. Words to the wise...if it isn't high pH it is solvent based and if it is solvent based at least where a cheap disposable cabon filter mask...unless your reproductive years are over...in which case go for it ;-) The "soy" and "orange" cleaner products usually contain mineral spirits.
http://en.wikipedia.org/wiki/Methylpyrrolidone
http://en.wikipedia.org/wiki/Methylpyrrolidone
I feel that the ease of removal depends entirely on the type of paint that was used.
Ablative normally comes off fairly easily with a scraper, hard paints seem to respond better to blasting or chemical strippers.
Sanding seems to work on all types, but I generally limit it to spots that don't respond well to the other methods.
Ken.
Ablative normally comes off fairly easily with a scraper, hard paints seem to respond better to blasting or chemical strippers.
Sanding seems to work on all types, but I generally limit it to spots that don't respond well to the other methods.
Ken.
Link: MSDS for Soy Strip
Yes, the soy strippers have N-Methylpyrrolidone. And yes some jurisdictions have labelled it a suspected reproductive toxicant. I can't yet find information on those studies as to what the tests resolved, or what levels, what concentrations, or what duration/frequency of exposure was considered toxic.
Not all solvents are equal. From your wikipedia link:
... it even mentions that NMP is used in drugs and in implantable medical items!
Let's compare the toxicity of the strippers by themselves. The more mainstream solvent strippers are made of plastic and organic solvents that are all known toxins and carcinogens if inhaled or in skin contact for small amounts of time. They're very volatile and require serious ventilation and breathing protection in regular use. They BURN if they touch your skin. They are toxic waste even before you use them.
The soy strippers produce just about no vapour by comparison If inhaled or in contact with skin... they are an irritant, not a poison or a carcinogen. Unused soy strippers do not require handling or treatment as toxic waste. You don't need a respirator to apply in outside conditions.
Let's consider what strippers are used for - removing paint. Bottom paint is a nasty toxin... that's why we use it. Ingesting or inhaling bottom paint dust is quite bad, which is why sanding bottom paint is a poor idea. (also it's very hard to recover and dispose of the dust)
Soy strippers with their longer working time, keep the stripped paint in suspension and remain workable for much longer than solvent-based strippers.
Taken all together, it's clear to me that soy strippers are much less toxic than solvent-based strippers, in actual use.
Finally, let's look at practicality and ease of use by the average boater.
Solvent based strippers
- gloves and ventilation mask essential
- special ventilation essential, even when a mask is used (working outdoors I still got a headache)
- disposable bunny-suit is recommended
- working time is short (sometimes an advantage) but you also have less time to scrape
- often harder to scrape
- more likely to attack gelcoat
- solvent still required for final cleanup (... more toxins)
- all residue, including leftover stripper, is toxic
Soy based stripper
- gloves recommended, especially when scraping
- ventilation mask not always necessary(I worked outdoors and the lightest breeze was sufficient)
- if you aren't getting dripped on, bunny suit not essential
- working time is long (eg overnight) but this also gives you more time to complete the scraping
- less likely to attack gelcoat
- final hull cleanup can be done with soapy water and a scrub-brush, or by pressure-washing
I remain convinced that soy strippers are a safer and easier chemical stripping alternative for the boat owner.
I've researched some of this, but most of this is from my own experience from using both types on our boat.
Bob, thanks for the awesome links. It was a heavy read but I think I got most of it.
Here's my takeaway of those studies:
- NMP can enter the body via inhalation and skin contact. Given NMP's low volatility, and further reduction in volatility when formulated as a paste stripper, skin contact is the most likely route of entry when used as a paint stripper (moral - wear gloves)
- long-term exposure of lab animals to NMP caused reproductive effects. This was at high levels, for several hours a day, for a few weeks. This would be equivalent to the exposure of a very incautious professional, not the weekend hull-stripper
- in both animal and human studies, test subjects were exposed to NMP at levels that would be FATAL if they were any of the other strippers (solvent or caustic). The humans even ingested 100 mg of NMP for the study, for crying out loud...
- NMP does not bio-accumulate; after exposure it's naturally eliminated from the body in a matter of hours or a few days. Other stripper solvents are notorious for bio-accumulation and long term damage to internal organs.
So, honestly, I'm even more convinced that these soy-strippers are very suitable and markedly safer for use by the average boat-owner.
I now suspect that, for the man, having 5 beers the night before is probably more toxic to the reproductive system than a weekend of hull-stripping with a soy stripper... but for the cautious couple who are planning a child, wait a week or two after stripping the hull before getting back to it...? And of course no thinking couple is going to knowingly involve a prospective or expecting mother in any chemical exposure, right?
I agree that potential reproductive toxicity should be spelled out on the label, but other than this... having read your links, I'm more confident now that soy-strippers with NMP are the least toxic of the available products for hull-stripping, and it's not a marketing ploy or deception to advertise this.
(Note - I do not work for a manufacturer or reseller of these strippers, but, honestly, they need to hire me )
Here's my takeaway of those studies:
- NMP can enter the body via inhalation and skin contact. Given NMP's low volatility, and further reduction in volatility when formulated as a paste stripper, skin contact is the most likely route of entry when used as a paint stripper (moral - wear gloves)
- long-term exposure of lab animals to NMP caused reproductive effects. This was at high levels, for several hours a day, for a few weeks. This would be equivalent to the exposure of a very incautious professional, not the weekend hull-stripper
- in both animal and human studies, test subjects were exposed to NMP at levels that would be FATAL if they were any of the other strippers (solvent or caustic). The humans even ingested 100 mg of NMP for the study, for crying out loud...
- NMP does not bio-accumulate; after exposure it's naturally eliminated from the body in a matter of hours or a few days. Other stripper solvents are notorious for bio-accumulation and long term damage to internal organs.
So, honestly, I'm even more convinced that these soy-strippers are very suitable and markedly safer for use by the average boat-owner.
I now suspect that, for the man, having 5 beers the night before is probably more toxic to the reproductive system than a weekend of hull-stripping with a soy stripper... but for the cautious couple who are planning a child, wait a week or two after stripping the hull before getting back to it...? And of course no thinking couple is going to knowingly involve a prospective or expecting mother in any chemical exposure, right?
I agree that potential reproductive toxicity should be spelled out on the label, but other than this... having read your links, I'm more confident now that soy-strippers with NMP are the least toxic of the available products for hull-stripping, and it's not a marketing ploy or deception to advertise this.
(Note - I do not work for a manufacturer or reseller of these strippers, but, honestly, they need to hire me
)Stripping??? my 2c
Depends on 1. How big the boat is 2. How much cash you have available 3. Whats on the bottom. If you have a boat over 30 ft with layers of old epoxy paint I would take Barnicle Bills advice and let the yard do it. If you have ablative paint all you have to do is sand off any build up and put a fresh coat on. Even with epoxy paint you dont really have to get it all off unless your going to race. You can sand or scrape the heavy stuff off smooth it out and leave any residue as a barrier coat for ablative paint. Dont do any work! scraping, sanding etc without a bunny suit, gloves and a good mask
Depends on 1. How big the boat is 2. How much cash you have available 3. Whats on the bottom. If you have a boat over 30 ft with layers of old epoxy paint I would take Barnicle Bills advice and let the yard do it. If you have ablative paint all you have to do is sand off any build up and put a fresh coat on. Even with epoxy paint you dont really have to get it all off unless your going to race. You can sand or scrape the heavy stuff off smooth it out and leave any residue as a barrier coat for ablative paint. Dont do any work! scraping, sanding etc without a bunny suit, gloves and a good mask
Best... use ablative paint.
But you still have something to deal with now. Good luck. I have had boats for 25 years and have always avoided stripping.
I'ld get a yard quote, I think. I don't mind painting an some power sanding, but that sounds terrible. Yu need to decide if it really NEEDS to come off.
Every 2 years give it a good power washing and a light sandiing with a vacuum sander. You should have no build-up.
But you still have something to deal with now. Good luck. I have had boats for 25 years and have always avoided stripping.
I'ld get a yard quote, I think. I don't mind painting an some power sanding, but that sounds terrible. Yu need to decide if it really NEEDS to come off.
i used a seven inch disc grinder with a soft back and sanding discs..took two full days..sanded complete boat less deck and washed down with acetone and then painted with interlux two part epoxy white ....with stripes..one just above water line with interlux brightsiide blue..if i was going to use just bottom paint reapplyed my job would have been much less but i decided to get away from that chalky blue stuff and i am only in fresh water so i am taking my chances with the two part epoxy...so far so good..pics of boat in my profile..
Hi All
We chemically stipped a CS36 Merlin, then sanded, took 2 full days with 2 people at it to get to the gelcoat. It just a nasty job and no easy way to do it if you are a do it yourselfer. Extra cost of 2 large bottles of rum, seems the more rum consumed the easier the job got. Moral of the story is start with the rum early, a happy stripper is a good thing. On the third day hold the rum until after appling the masking tape and VC tar, follow up with VC17. Lauch and sail. Note the increase in hull speed !
LOL Sonya
We chemically stipped a CS36 Merlin, then sanded, took 2 full days with 2 people at it to get to the gelcoat. It just a nasty job and no easy way to do it if you are a do it yourselfer. Extra cost of 2 large bottles of rum, seems the more rum consumed the easier the job got. Moral of the story is start with the rum early, a happy stripper is a good thing. On the third day hold the rum until after appling the masking tape and VC tar, follow up with VC17. Lauch and sail. Note the increase in hull speed !
LOL Sonya
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