THANK YOU ROSS!/ Peel away advice

[rgranger]

Ross: your peel away advice was dead on the money. I put some KOH and a bag of garden lime (hydrated lime) into a 5 gal PVC bucket along with a smidge of glycerin to keep it moist and rolled it onto my boat's bottom with a standard paint roller. I left it for a few days and hit it with the pressure washer. The paint just flaked right off (see pics). I'll suck up the chips with my shop vac once they have dried out. Damn I wish I new this trick two boats ago. The next time I do this I think I'll use plaster of Paris as the binding matrix since I'm almost certain the active ingredient is the KOH and I'll add a 5lb bag of sugar. The sugar should help keep it moist and "syrup like". It cost me less than $5 since I already had the KOH but I think anyone could just use a few cans of drain-o if they don't have access to KOH or NaOH and any binding agent (like powdered lime or plaster) and something to keep it moist (like paper or maybe my sugar idea?). I have a few tough spots to rework and I'll let the list know if the sugar idea worked or not.

Thanks again!

r

 

[caguy]

Thanks for sharing, this is good information for all of us.

 

[Ross]

The only advantage i see to the hydrated lime is that it is also alkaline. You don't want the gypsum to harden.

 

[Ross]

rgranger, doesn't calcium sulfate have an acid reaction?

 

[rgranger]

rgranger, doesn't calcium sulfate have an acid reaction?

Ah... no. Actually, calcium sulfate (the sulfate part), is the conjugate base of sulfuric acid. Sulfuric acid is H2SO4 and it is diprotic (It can donate two protons). The first proton donation is considered "strong" and leaves without producing an equilibrium situation...

H2SO4 --> H+ + (HSO4)-

however, the second proton is in equilibrium with the associated form

(HSO4)- <--> H+ + (SO4)-2

So when you put calcium sulfate in water... and the sulfate participates in the above equilibrium, you get....

(SO4)-2 + H20 <--> (HSO4)- + OH-

... so the net result is a base (the hydroxide part).

But the lime worked and is probably cheaper. I'm just thinking about the consistency of it all and wondered if the plaster would make a better compound.

Honestly, I was shocked at how well it worked and lamented on the hours of time I've spent with citrus strippers and a scrapper.

Thanks again for the tip.

r

 

[Ross]

Thanks. and you're welcome.

 

[CalebD]

So, one pound of potassium hydroxide (perhaps a lawn fertilizer or such) and hydrated lime mixed with water and some thickener would work for stripping a hull?
I wonder if the chemicals would mess with natural gelatin?
Almost too good to be true.

 

[rgranger]

So, one pound of potassium hydroxide (perhaps a lawn fertilizer or such).

Caleb

I don't think you want lawn fertilizer. That is mostly potassium nitrates, phosphates and ammonium nitrates and phosphates. HOWEVER the active ingredient in Drain-o is sodium and potassium hydroxide. Go to the plumbing section at Lowes or Home Depot and read the ingredients on the drain cleaners. You might be able to get an off brand for even less than Drain-o.

So I'm thinking, two cans of drain-o, a bag of lime and a 5lb bag of sugar mixed in a 5 gal PVC bucket and you are good to go. The sugar is just to make it sticky and it is hygroscopic so it should keep the paste moist for a longer period of time. I used glycerin but I think regular sucrose would serve the same purpose. Poor it into a paint pan and roll it on. Come back in a few days and pressure wash it off.

 

[Ross]

The brand name "Red Devel lye" is pure sodium hydroxide most grocery stores sell it in the cleaning supplies section.

 

[Ross]

Be sure that you use hydrated lime and not ground limestone.

 

[rgranger]

Be sure that you use hydrated lime and not ground limestone.

And wear EYE PROTECTION! You get this stuff in you eyes and you will have problems.

 

[Allan12210]

And wear EYE PROTECTION! You get this stuff in you eyes and you will have problems.

And big gloves otherwise you'll saponify all your esters.

 

[CalebD]

Thanks for clarifying the 'ingredients' gentlemen.
I have been using an ablative paint on our hull for a number of years but I am thinking it is time to strip down some of the excess buildup.
I suppose the ambient temperature may have an effect on the chemical reactions.
Warmer temps might work faster? Not that I'm in a rush.

 

[Richard Bryer]

This is a keeper, thank you very much everyone
Do you think it will work on VC17? Also what kind of temperature did you use it in?

 

[rgranger]

Caleb & Richard:

With respect to temperature...I'm guessing the bigger issue is keeping it moist. Once it hardens up and crystallizes on the hull, the active ingredient (free hydroxide ions) is no longer mobile and able to do its job so well. That is why I added glycerin to my batch... just to keep it moist. So, the cooler temperatures (it was mid 60's during the daytime) might have been a plus since it would obviously dry out faster in the hot sun. The commercial peel away uses a paper applied to the paste to keep it from drying out. I don't like to think about how you would go about doing that. I don't want to get that close to this stuff. I used a 6' pole on a paint roller and didn't get a drop on me.

I'd just use it as is, and if it hardens up too fast, mist it with a garden hose to moisten it up some...that should get it working again... or blast it off with the pressure washer and if you still need to get more paint off of your hull, do it again. This is so cheap compared to the $75/gal commercial stuff. At $3/bag for the hydrated lime, $5 for the lye or drain cleaner and $3/bag for some sugar and you are still under $15 for a three gallon batch of this stuff.

And I have no idea if it would work on CV17 ... try it and let us know.

 

[Bad Obsession]

This is a very cool solution. I want to pull my boat next year and have it soda blasted. That would cost me about $900 for my hull. It would be cool if I could strip the paint this way.

Maybe the powers that be could post this somewhere with a link, like Mainesail's page.

 

[Don Crowther]

This sounds almost to good to be true!! I'm about half way done on the bottom just the worst bit left down by the strut and rudder.
Thanks for posting this

 

[rgranger]

Update on Homemade Peel Away

Hey All: Just wanted to let you know a bit more that I've learned about this stuff. My neighbor is restoring a Bruce Roberts and asked me if this homemade stuff would work on his top side paint.... and I said

I had about a half gallon left over from my job so I suggested he test it on a spot. It worked great. I don't know what kind of paint it was but it came up just fine and left the original gel coat exposed. :dance:

You got to love list serves...

 

[Ross]

Re: Update on Homemade Peel Away

Just remember skin doesn't bother it at all.