removing silicon

cfretz · Post by **cfretz** » Sun Jan 28, 2007 11:22 am

In the past someone placeed a heavy bead of silicon on the rubrail/hull joint. I have removed the rail but the silicon is stuck to the hull. how do i get it off? I'm going to grind and put a layer of glass. will any residue affect the bond?

Post by **Tim** » Sun Jan 28, 2007 12:18 pm

Welcome to one of the funnest parts of boat repair: dealing with old silicone. Unfortunately, it seems that if the silicone doesn't peel right off immediately with no effort, then it sticks more tenaciously than just about anything. That's one of the worst things about silicone: it seems to fail to work properly when you want it to, but it sticks forever when you don't want it to.

Silicone tends to resist almost all efforts to remove it. Mechanical means are your best bet--scrapers, etc--to remove the residue. Even this often tends to leave a fine film behind. The possibility of silicone contamination is very real, so grinding the residue should be looked upon as a last resort, if at all, and should only be undertaken with care to avoid contaminating other areas.

You must remove the silicone completely in order to ensure a good bond with fiberglass or paint. Try putty knives, 5-in-1 tools, and scrapers. Use acetone and other solvents to try and remove any residue that remains.

Silicone is pure evil. Good luck!

Hirilondë · Post by **Hirilondë** » Sun Jan 28, 2007 7:03 pm

Sometimes you can rub it off with a thin rubber gloved hand or even a bare hand. It may roll off in small pieces if you use short firm strokes. I sometimes resort to using a very sharp chisel held flat on the surface like you would finishing off a mortise for hardware. This method can work well on flat surfaces like you may have in your rubrail situation. You need to be very careful doing that as you may cut into the gel coat if you lift the handle at all.

Silicone should be illegal. And the use of 5200 should require a license. (or at least some common sense in knowing where it is needed and where it isn't)

I just finished replacing 10 fixed ports on a Hinckley SW 51. They are laminated safety glass. They were bedded in 5200 and then when they started to leak someone had the bright idea to put a bead of silicone on the outside. Needless to say, removing them and cleaning for the new pieces of glass was tedious to say the least.

CharlieJ · Post by **CharlieJ** » Sun Jan 28, 2007 8:15 pm

Tedious?? I bet *grin*

Looks like we're all in agreement on silicone. Oh man do I hate the stuff.

Get as much of it off as you can before you sand- if there's silicoine left there, the sanding will just force it into the scratches the sander makes and then it's forever. Personally I'd scrape til I started scraping off gel coat. Since you are going to glass anyway, ruining the gel coat doesn't much matter.

Jedediah · Post by **Jedediah** » Thu Feb 01, 2007 12:39 pm

Might try DeBond 2000. Was recommended here at the local Fisheries store as a way to remove just that. And so far I have to say it's worked well with the silicon I've used it on (maybe I just have special old silicon that it likes though...). Spray it on, wait a few minutes and it all wipes right off--depending on thickness. But it's very good at removing that last thin film that seems to stick after scraping off the rest.

Tried it on the old windows trying to get the halves to split. My guess is they were glued with 5200 or such. Only softened the plastic.

catamount · Post by **catamount** » Wed May 02, 2007 9:19 am

I've been using BoatLife Release in combination with a sharpened putty knife or chisel to remove the old silicone from my boat. So far it seems to be working OK.

Hulukupu · Post by **Hulukupu** » Tue Nov 04, 2008 11:50 pm

I am also dealing with the problem of silicone removal prior to putting on an epoxy primer on my deck. The silicone is weathered and often peals up when I rub it with my thumb. Once the stringy snot of old caulk is gone, do I have to worry about germs (=residue)? Is there any test, short of putting on some primer to see if it reacts?

David · Post by **David** » Wed Nov 05, 2008 12:31 am

Silicone sealant is impervious to most everything including heat, cold and enormous stresses. That's why it is used to glue glass panes to the sides of skyscrappers. It is not affected by UV, it does not weather--it is perfect for what it was developed to be. All that makes it damned tough to remove and it seams to always leave a thin residue. Since alcohol is the best solvent to use to clean up uncured silicone, you might try alcohol and a scrub pad. Good luck.

Post by **Tim** » Wed Nov 05, 2008 7:07 am

Hulukupu wrote:I am also dealing with the problem of silicone removal prior to putting on an epoxy primer on my deck. The silicone is weathered and often peals up when I rub it with my thumb. Once the stringy snot of old caulk is gone, do I have to worry about germs (=residue)? Is there any test, short of putting on some primer to see if it reacts?

Always, always assume that you have contamination. The worst type is that which you cannot see, but it likely still lurks behind even if you've peeled off the beads. This near-invisible residue will ruin all future seal jobs, paint jobs, or other.

It takes heroic measures to completely remove all silicone residue. Scraping, solvent, and eventually careful sanding (being very wary of spreading the contamination around or forcing it into the surface through the sanding efforts) are your best bets. Depending on the circumstances, it's often best to simply scrape away entire surfaces of gelcoat and rebuild the surface rather than risk silicone contamination.

Silicone is pure evil because of its tenacity and tendency to linger behind despite one's best removal efforts.

Quetzalsailor · Post by **Quetzalsailor** » Wed Nov 05, 2008 9:55 am

There must be a 'quick and easy' way to know when you're successful? That's a question, not a pontification.

I think lots of water while wetsanding after removing everything you could feel or see might be a useful approach, presuming wholesale destruction of the substrate is not desirable. Perhaps rubbing compounds or even Soft Scrub would do.

I think testing with some substance that you can get back off, maybe like severely thinned oil paint, might do. The paint would ciss (it's possible that I cannot spell) at, pull back from, contamination.

Silicone's pretty wondrous stuff. Taking the cue from architectural 'structural glazing', I've glued broken curved greenhouse glass back together and it's still there after about 30 years. I've also glued the bottom half of a broken glass bottom finial back on to an antique chandelier. That's a 3/8" dia. joint loaded in tension 24/7 for about 10 years.

Hulukupu · Post by **Hulukupu** » Thu Nov 06, 2008 3:10 pm

Thanks, all, for the feedback.

While I marvel at the longevity of silicon (what other products in a tube give you a 20-yr guarantee?), it doesn't seem to have held up very well as a marine deck sealer- most of it peels very easily.

I'll try sanding the gel coat where practical and using rubbing alcohol.

Summersdawn · Post by **Summersdawn** » Thu Nov 06, 2008 3:33 pm

To test for remaining residue, mist it with water from a spray bottle. If the water beads up, silicone remains.I found with silicone residue it takes many solvent wipes to remove. Don't bother misting with water after every wipe on/wipe off, you'll only frustrate yourself. Use the 2 rag method, one with solvent, and a clean one to wipe the solvent off. Don't wipe towards the outside, wipe towards the center to prevent moving the silicone onto adjacent surfaces. Wipe 10-15 times, then test with water. You'll need to do this a number of times to pass the water mist test. I tried several different solvents (acetone, alcohol, turpentine, mineral spirits) trying to find a magic bullet, but didn't. Perhaps one of the silicone removers (such as debond) might be more effective. Patience is what finally removed mine.

Ceto · Post by **Ceto** » Fri Nov 07, 2008 12:47 am

I use a metallic bristle brush on a drill. I use the edge of the brush. You need to keep a steady hand so as not to damage the fiberglass or the gelcoat although some damage is unavoidable.

I figure it's easier to repair small damages rather than spend the time to remove the silicon...

dougcn · Post by **dougcn** » Sun Apr 26, 2009 9:35 pm

I just finished removing 88 ft of caprail, 3/4 of which was bedded with silicone caulk and got pretty good at removing the silicone.

- Scrape bulk of caulk with a 1-1/2" razor sharp chisel. Resharped frequently on a belt sander, as the screw heads will dull it quickly.

- Spray on Boatlife Release. This stuff actually works. I've got no idea what's in it, so I headed the warnings and used a respirator and nitrile gloves.

- Scrub with a scotchbrite pad soaked with more Boatlife Release. Use the chisel to loosed any remaining reside.

- Wide down with rag/ paper towels soaked with Boatlife Release.

Though not fun, this job was much easier than any past attempts to remove silicone caulk. I'm really impressed with the Boatlife Release produce and it's much less "hostile" than many of the solvents I've tried in the past. I must sound like an infomercial, but I'm really amazed at how well this stuff worked.

Doug

Hirilondë · Post by **Hirilondë** » Mon Apr 27, 2009 7:35 am

Doug,

Glad you were so successful at removing the silicone. Have you started replacing the caprail yet? What I am really curious to ask is: Does your new bedding caulk stick to the cleaned surface? Aside from being a real nuisance to remove, what many of us dread is the prospect that the new sealant won't adhere to the site of the previous silicone. It sounds like you did a thorough job. And for all of our's future projects, I hope Boatlife Release turns out to be the product many of us have been looking for.

This post inspired me to do some research on Boatlife Release. I found a lot of mentions and descriptions, but none containing anything about the ingredients. Based on the descriptions it would seem that there are no seriously aggressive solvents in it, at least not in any quantity, but I won't swear to that without seeing a MSDS.

I did however find another wonderful, insightful, highly technical, detailed video on caulking. Boatlife tips is another amazing example of how little some of us, myself in particular, know about doing a thorough caulking repair.

Post by **Tim** » Mon Apr 27, 2009 8:23 am

Hirilondë wrote:I did however find another wonderful, insightful, highly technical, detailed video on caulking. Boatlife tips is another amazing example of how little some of us, myself in particular, know about doing a thorough caulking repair.

Keep watching these videos, Dave, and someday I'm sure you'll get the hang of it. ;<)

s/v Faith · Post by **s/v Faith** » Mon Apr 27, 2009 10:34 am

dougcn wrote:........I'm really impressed with the Boatlife Release produce and it's much less "hostile" than many of the solvents I've tried in the past. I must sound like an infomercial, but I'm really amazed at how well this stuff worked.

Doug

Like the others, I wonder if it really did work. I am sure that as you write, the apparent silicone did come off. The 'debond' products are marketed as a 'release agent' and not as a solvent. They break the bond, which is not necessarily the same thing as removing the product.

3M 5200 will bond so well that you can destroy not just the gelcoat, but the underlying fiberglass when you try to force something away from it's grasp. I am glad we have a product (even if so expensive) that helps with this. Silicone however has (among it's other bad habits) a relatively low adhesive bond.

I have seen some instances where it would be handy to be able to 'release' silicone, like the wench blocks that had been bedded in the nasty stuff. I was able to pry them loose, but it was a destructive process.

The issue, and the reason I started typing has to do with the real problem with silicone, why it should (IMHO) never be used on fiberglass or on wood, and should require a license to purchase. The silicone you see is only part of the problem, the bigger issue is the oil from the silicone that seeps into the paint, gel coat, and even into the very fiberglass its self.

You can THINK you removed it, but once you paint over it, the paint fails. It causes fish eye in maddeningly small concentrations. I had a real problem with this that I actually ended up having to gouge out perfectly good (contaminated) fiberglass to get rid of.

My cleaning standard was the 'water break free' state. This is the point where water no longer beads, but sheets when sponged. It turns out this was not good enough in some areas, and I have some areas on my deck where the paint has failed. I know it was silicone contamination because one area is where someone had bedded the jib tracks....

Good luck to you with your project. If your calk is compressed, it probably does not rely on the adheasive bond like paint does anyway.

I am sorry for the long post, but I have been told I have a problem with this issue... I find no treatment for it that helps other then an occasional rant on the subject. ;)

boatsnh · Post by **boatsnh** » Mon Apr 27, 2009 4:37 pm

I have found "Prep-Sol" or something like it to be very helpful prior to painting. It's sold at autobody paint suppliers. The painters use this as a "wipe down" product to pick up oil, grease & silicone - It states on the can "silicone" as something it removes. I've found a couple/3 wipe downs with the solvent followed with dry cloth wipe down has worked for me - I have used it as a wipe down on areas the prior owned used silicone, but I still had to remove the stuff with razor blades & scrapers. I use the prep sol a couple times prior to sanding so I don't gringd the silicone in.....But I also tend not to use much Silicone adhesive - except the stuff I used to hold down the acrylic hatch tops when I rebuilt them 3 years ago. Same stuff they use on skyscrapers. It's held up great so far, and very color stable.

Rachel · Post by **Rachel** » Mon Apr 27, 2009 5:23 pm

I, too, would love to know if the silicone remover has worked to the point of removing the invisible oil contamination that seems to hang on permanently. I loathe silicone. And for some reason, people seem particularly attracted to it as a caulking product; I'm not sure why. Is it the "Knox Blocks" jiggly "friendliness" of it? The fact that it's clear? Whatever it is, it certainly seems to call to people.

Rachel

Post by **Tim** » Mon Apr 27, 2009 5:35 pm

Rachel wrote: And for some reason, people seem particularly attracted to it as a caulking product; I'm not sure why.

I have some ideas why:

1. It's cheap compared to other sealants

2. It's available absolutely everywhere

3. It's cheap

4. Lots of books and online experts suggest it as a viable substance

5. It's cheap

6. It's frequently used around the household, hence it's likely to be on hand

7. It's cheap

Silicone is pure evil. I usually physically scrape off the top layer of gelcoat to which the silicone was affixed to help ensure contaminant removal. Setting the boat afire might be easier and more effective.

Rachel · Post by **Rachel** » Mon Apr 27, 2009 6:36 pm

I like the fire idea - that would probably get most of it off.

Dave, I just watched that video. I'm stunned. I sure HOPE the Boatlife Release isn't toxic, since the guy practically used it as salad dressing ("Let's just spray it on our bare hand....")

And the wiping to decontaminate? Why have a whole rag if you are only going to use the same two square inches the whole time?

Did you watch the part about the "lifesaving" kit afterward? Amazing.

I hope I don't sound too snobby or anything here, but geez, that was terrible.

Rachel
(still reeling slightly and wondering if it was serious...)

dougcn · Post by **dougcn** » Mon Apr 27, 2009 10:58 pm

Okay, so I've given this Boatlife Release stuff a lot of thought an concluded that it must be salt water. After all, I know of nothing that makes silicone fail faster.

Seriously, I'm not sure what the ingredients are, but it does seem to work well. It doesn't seem to attack the fiberglass or gelcoat at all.

I haven't gotten to the rebedding part yet, but I have tested the surfaces where I removed the silicone. I sprinked water on - no beading. So I poured water on. Still no beading. Then I smeared the water around. Still no beading. So I'm inclined to think I got the residue off. Still, I'm a bit paranoid and really don't want to do this caprail project again, so I'm going to wipe down everything with Interlux 202 solvent. I'm thinking that should help.

I found another great tool in this process too -a nylon "wire" wheel which is impregated with abrasive called a NYALOX. Using the medium grit Orange colored wheel on a drill I was able to thoroughly brush out the raw glass part of the hull deck joint, without the usual problems of wire wheels shedding metal bits.

So hopefully I won't be writing again this summer explaining how I had to re-do the caprail again!

Doug

Hirilondë · Post by **Hirilondë** » Tue Apr 28, 2009 1:12 am

Rachel,

There was nothing the guy in the movie did that was a good technique and he certainly was not thorough. Using a paint can opener did nothing to remove old caulk from inside the space behind the trim. That means all he did was smear the new stuff into the corner. He didn't do anything to force the rag into the space he didn't create with the opener so the Release did nothing but maybe clean the gel coat below the eyebrow trim. His idea to push the cartridge instead of cutting a proper angle on the tip and pulling it is the stupidest idea I have ever seen. I only linked the video because I know how much Tim likes them :>)

Doug,

I sincerely doubt that Boatlife Release is any better than plain solvents like acetone for cleaning silicone. If you have good results it will probably be because you were thorough in your procedures. I am convinced the marketing for it was handled by the same people that developed the marketing for Interprotect.

Oscar · Post by **Oscar** » Tue Apr 28, 2009 11:07 pm

Dave, here's your MSDS:

http://www.jamestowndistributors.com/us ... 1_MSDS.pdf

Hirilondë · Post by **Hirilondë** » Wed Apr 29, 2009 12:28 am

Oscar wrote:Dave, here's your MSDS:

http://www.jamestowndistributors.com/us ... 1_MSDS.pdf

Ah, thanks. Primary ingredients are petroleum distillates. So it is a relatively safe material. Flammable and an irritant. Most people will probably find they can get it on their hands with little or no problem. But as the MSDS describes it as an irritant I think if I were making a video for the amateur public I would at least wear nitrile gloves and pretend I was being careful.

Oscar · Post by **Oscar** » Wed Apr 29, 2009 8:57 am

I would at least wear nitrile gloves and pretend I was being careful.

After years of exposing myself to all kinds of scary stuff I now have a box of 100 in the shop at all times. Basically I do like the doctor and grab a pair as I walk in the door and ask the project: "How are you feeling today?" Once you get used to it you forget you have them on.

Rachel · Post by **Rachel** » Wed Apr 29, 2009 12:22 pm

Agreed, Oscar. I wish they'd been around when I worked at a gas station when I was a teenager. I thought my "fingerprints" were never going to be clean again!

My favorite trick is to put two or three gloves on each hand (especially when epoxying), so that I can just peel of a gunky one and not fiddle with getting another one one (which is when I found myself getting epoxy on my hands).

It is pretty pathetic to have the fellow in the video just spraying the stuff on his bare hand. Set an example! Sheesh.

R.

Oscar · Post by **Oscar** » Wed Apr 29, 2009 1:26 pm

My favorite trick is to put two or three gloves on each hand (especially when epoxying), so that I can just peel of a gunky one and not fiddle with getting another one

Hmmm, I have to try that. Wonder how many I can get on one hand.......

Rachel · Post by **Rachel** » Wed Apr 29, 2009 5:58 pm

Box of 100. Now I can't get rid of this image of you with 50 on each hand. Hee!

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