Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?

[jim aridas via CnC-List]

Just an aside on the true coal tar epoxy, like what rustolem co sells. My 82' 
C 34 had a cast iron centerboard. wire wheeled the board, painted 2 coats of 
coal tar and after 12 yrs of owning the boat there was no sign of rust bleeding 
thru. Awesome stuff for protecting steel in salt water !
Jim Aridas
Previously Galaxy 34' 1982 K/CB


From: Dave via CnC-List 
Sent: Monday, April 5, 2021 2:08 PM
To: Matt Janssen ; Stus-List 
Cc: Della Barba, Joe ; Dave 
Subject: Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?


Matt – thanks for the detail, very very much appreciated. Yes likely VC tar.   
My Dutch/Scottish heart also warms to the reuse of a disposable brush, gripped 
in a very tight fist.   



Dave



Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10



From: Matt Janssen<mailto:matt.s.jans...@gmail.com>
Sent: April 5, 2021 11:03 AM
To: Stus-List<mailto:cnc-list@cnc-list.com>; Dave S<mailto:syerd...@gmail.com>
Cc: Della Barba, Joe<mailto:joe.della.ba...@ssa.gov>
Subject: Re: Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?



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 t

Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?

[Matthew via CnC-List]

FWIW, I don’t like that type of bristle for most epoxy work (I use West System) 
as hairs come out and get stuck in the epoxy.  I use plastic bristle 
throw-aways instead.  However, if you cut the bristles short on the hair 
brushes, they are very good for pushing West System/colloidal silica mixture 
into tight places.

 

From: CHARLES SCHEAFFER via CnC-List  
Sent: Tuesday, April 06, 2021 12:20 PM
To: Stus-List 
Cc: CHARLES SCHEAFFER 
Subject: Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?

 

A box of chip brushes lasts me a few years and if you do a lot of boat projects 
and stuff around the house, it saves a ton of money to buy in bulk.  I use them 
for epoxy, painting, varnishing and throw away after use.   

  

https://www.amazon.com/Single-Brushes-Stains-Varnishes-Acrylics/dp/B078XJ2DCJ/ref=sr_1_1_sspa?crid=V18C3HO3BGC2
 
<https://www.amazon.com/Single-Brushes-Stains-Varnishes-Acrylics/dp/B078XJ2DCJ/ref=sr_1_1_sspa?crid=V18C3HO3BGC2=1=chip+brushes+2+inch+bulk=1617725693=chip+brush%2Caps%2C216=8-1-spons=1=A1HD84JZ5JR3NU=ZW5jcnlwdGVkUXVhbGlmaWVyPUExQTlNNlhOUlNMS1kxJmVuY3J5cHRlZElkPUEwNjQ1NDc0MUVNR01XTEs3SlhLNSZlbmNyeXB0ZWRBZElkPUEwOTYzODM3RFgwWjJCNjNKVjAwJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==>
 
=1=chip+brushes+2+inch+bulk=1617725693=chip+brush%2Caps%2C216=8-1-spons=1=A1HD84JZ5JR3NU=ZW5jcnlwdGVkUXVhbGlmaWVyPUExQTlNNlhOUlNMS1kxJmVuY3J5cHRlZElkPUEwNjQ1NDc0MUVNR01XTEs3SlhLNSZlbmNyeXB0ZWRBZElkPUEwOTYzODM3RFgwWjJCNjNKVjAwJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==
 

  

Chuck S 

  

  

On 04/05/2021 11:30 AM Shawn Wright via CnC-List mailto:cnc-list@cnc-list.com> > wrote: 

  

  

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 <mailto:shawngwri...@gmail.com>  

S/V Callisto, 1974 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 <mailto: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 dr

Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?

[CHARLES SCHEAFFER via CnC-List]

A box of chip brushes lasts me a few years and if you do a lot of boat projects 
and stuff around the house, it saves a ton of money to buy in bulk.  I use them 
for epoxy, painting, varnishing and throw away after use.  

https://www.amazon.com/Single-Brushes-Stains-Varnishes-Acrylics/dp/B078XJ2DCJ/ref=sr_1_1_sspa?crid=V18C3HO3BGC2=1=chip+brushes+2+inch+bulk=1617725693=chip+brush%2Caps%2C216=8-1-spons=1=A1HD84JZ5JR3NU=ZW5jcnlwdGVkUXVhbGlmaWVyPUExQTlNNlhOUlNMS1kxJmVuY3J5cHRlZElkPUEwNjQ1NDc0MUVNR01XTEs3SlhLNSZlbmNyeXB0ZWRBZElkPUEwOTYzODM3RFgwWjJCNjNKVjAwJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

Chuck S



> On 04/05/2021 11:30 AM Shawn Wright via CnC-List  
> wrote:
>  
>  
> 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 mailto:shawngwri...@gmail.com
> S/V Callisto, 1974 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 mailto: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 

Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?

[John and Maryann Read via CnC-List]

I did this project when first purchased our 34 22 years ago.  What you describe 
sure sounds like VC tar to me.  PO used VC 17 paint (fresh water) with VC Tar 
as barrier coat that had eroded in many areas.  Used chemical stripper very 
sensitive to heat and humidity and very toxic.  Apply stripper, put on paper 
plastic sheeting so does not dry, let stand for X time and strip off.  Found a 
heavy plastic scraper worked well to remove.  Must wear protective clothing or 
will get chemical burns on skin and respirator for toxic fumes.  Bear of a job 
but got to clean gel coat with minimal sanding / fairing required.  6 coats 
epoxy barrier coat and still going strong.

 

John and Maryann

Legacy III

1982 C 34

Noank, CT

 

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

Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?

[Dave via CnC-List]

Matt – thanks for the detail, very very much appreciated. Yes likely VC tar.   My Dutch/Scottish heart also warms to the reuse of a disposable brush, gripped in a very tight fist.        Dave Sent from Mail for Windows 10 From: Matt JanssenSent: April 5, 2021 11:03 AMTo: Stus-List; Dave SCc: Della Barba, JoeSubject: Re: Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal? 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. Chemical stripping - I used Citristrip and a glass cleaner (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.   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  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 27 Mk VEDUAMRYC, 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 ☹ JoeCoquinaThanks 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

Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?

[Bill Coleman via CnC-List]

I found this very interesting as well. I had a sander start spinning disks off 
last year, melted hooks must have been the problem, thanks for that tip!

Also, I have tried to buy the dust cyclone from Rockler for $89 on sale, both 
times I got a cancellation notice from them a few days after purchasing, so I 
gave up.  Good to hear that they work as advertised.



And the chip brush is just a coarse brush that you wouldn’t use for painting, 
but for brushing metal chips away from your drill or cutter as you were 
machining. 

 

 

Bill Coleman

Entrada, Erie, PA

 

 

 

From: Shawn Wright via CnC-List [mailto:cnc-list@cnc-list.com] 
Sent: Monday, April 05, 2021 11:30 AM
To: Stus-List
Cc: Shawn Wright
Subject: Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?

 

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 35

https://www.facebook.com/SVCallisto

 

 

On Mon, Apr 5, 2021 at 8:03 AM Matt Janssen via CnC-List 
 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

Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?

[Shawn Wright via CnC-List]

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 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
>
> (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
>
> 
>  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 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 

Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?

[Matt Janssen via CnC-List]

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
   
(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
   

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 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

Stus-List Re: [EXTERNAL] Re: Coal tar bottom paint removal?

[Della Barba, Joe via CnC-List]

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