While I don't have a tar bottom, I enjoyed this thorough account as there are some good general tips. What is a chip brush?
Thanks -- Shawn Wright shawngwri...@gmail.com S/V Callisto, 1974 C&C 35 https://www.facebook.com/SVCallisto On Mon, Apr 5, 2021 at 8:03 AM Matt Janssen via CnC-List < cnc-list@cnc-list.com> wrote: > Dave, > > Is it possible you are trying to remove VC Tar or similar? > > Coal tar epoxy is the corrosion protection system we typically spec for > steel sheets in a marine environment. Bluewater makes a bottom barrier coat > for boats, but I suspect it's for commercial use on steel hull barges etc. > > If you're dealing with VC Tar as Joe and others have suggested, then > misery loves company. I am the final stretch of the same project. > > For me the tar was softer, it smelled terrible and was still somewhat > tacky in warm temps. After much trial and error I settled on two techniques > that worked for me. > > 1. Chemical stripping - I used Citristrip and a glass cleaner > > <https://www.homedepot.com/p/Anvil-4-in-Glass-and-Tile-Scraper-GTS-ANV/309996591?>(4-inch > wide razor blade) in lieu of a putty knife. With the razor blade (lots of > replacement blades), and a little practice, i was able to peel off two or > three layers of paint at a time and leave a smooth fair surface. On the > tar, i was able to get between the tar and gel coat without gouging the > hull. My boat was raced by the original owner and had a decent bottom, but > had suffered from paint build up. While this sounds tedious, it minimized > the fairing and longboarding. The rub is the stripper needs the temps to be > close to 60-F (15-C) to work and needs to sit for at least an hour or two. > If you're in direct sunlight or windy, you'll want to cover the stripper > with plastic. You want to avoid letting it dry out. (Another boat in the > yard didn't use plastic, but just mist the gel with a water bottle to keep > it from drying out.) With the citristrip, i was able to apply it and leave > it overnight covered with plastic and then come back to scrape it the next > day. It seemed to work up to about 3-layers of paint. > 2. Mechanical Removal - Unfortunately, I counted 12 separate colors of > bottom paint before getting to the tar, i'm located in the NE and with a > hard launch date, i had to use a mix of chemical and mechanical removal. > The only system that worked for me without destroying the hull shape was a > 6-inch random orbital sander using 80-grit Mirka Abranet pads. The Mirka > are a mesh pad and do not clog with the tar as long as your dust collection > system is decent. I used a home depot dust stopper > > <https://www.homedepot.com/p/Dustopper-HD12-High-Efficiency-Dust-Separator-HD12A/315749552> > separator > before the shop vac. It is stupid expensive for what it is... but it really > works and saves your shop vac filters. I could get 10 to 15 minutes out of > the Mirka pads. I've gone through close to 30-pads in the project. > > > I tried using traditional 36-grit pads but they were dulled after about > 5-minutes. Also tried the Bahco carbide scrapers. Those worked well > for level surfaces (e.g the rudder that you drop and put on saw horses) but > it was tough sledding to work on your back under the hull. If you do go > that route, bevel the edges of the blades and you won't gouge the hull. > > If you're still here, a few other lessons I learned the hard way. > > Managing heat on the pads was important. The Mirka pads do not insulate > the hooks from heat. So you'll absolutely need to use pad protectors. If > you don't, you'll melt the hooks on your sander and your disks will be > flying off the sander by lunch on the first day. I lost a few days waiting > for new parts when this happened to me... I also found lighter pressure on > the sander worked better. Letting the pad spin faster allowed it to chew > more of the material away. Easier on the shoulders too. > > Switching back to the stripper, I applied with a chip brush. Someone in > the yard pointed out that i should only be brushing in one direction. Most > have a wax in them that helps prevent drying out. Applying in one direction > certainly helped increase the working time of the gel. Being dutch, i was > able to wash the chip brush in hot water and used one brush for the whole > job. > > Best of luck with the project -- cheers, > > matt > > C&C 27 Mk V > EDUAM > RYC, NJ > > > > On Mon, Apr 5, 2021 at 8:51 AM Della Barba, Joe via CnC-List < > cnc-list@cnc-list.com> wrote: > >> I think this might mean coal tar epoxy barrier coat, which is nice until >> it starts coming off ☹ >> >> >> >> Joe >> >> Coquina >> Thanks to all of the subscribers that contributed to the list to help >> with the costs involved. If you want to show your support to the list - >> use PayPal to send contribution -- https://www.paypal.me/stumurray >> Thanks - Stu > > Thanks to all of the subscribers that contributed to the list to help with > the costs involved. If you want to show your support to the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray Thanks > - Stu
Thanks to all of the subscribers that contributed to the list to help with the costs involved. If you want to show your support to the list - use PayPal to send contribution -- https://www.paypal.me/stumurray Thanks - Stu
