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Author Topic:   Be careful with acetone and gelcoat.
T Party posted 03-03-2003 04:25 PM ET (US)   Profile for T Party  
Last week I was using some acetone on a cleaning rag to clean off some goo and dirt on my console. Just as I was finishing, it started raining, so I put the cover on the boat and left. The rag was left in the stern area on the non-skid (where I carelessly dropped it). Five days later, I uncovered the boat and started working on it again. I picked up the rag, and noticed that the non-skid under the rag didn't look right - it was all cracked and an area about the size of a silver dollar flaked right off down to the glass. Needless to say, I am disappointed (though my stern interior was already dinged up and had some worn spaces) and will be reading the threads about repair of non-skid.

I'm posting this so others might learn from my mistake. Ouch.

triblet posted 03-03-2003 04:31 PM ET (US)     Profile for triblet  Send Email to triblet     
I think I read somewhere in the BW owners manual
not to use acetone on gelcoat. But the gel
coat repair stuff I use (not Spectrum) says to
clean the surface with acetone.


Montauk posted 03-03-2003 04:42 PM ET (US)     Profile for Montauk  Send Email to Montauk     
There are two items that are highly over used and promoted on the internet. First is Acetone, it is too "hot" to be used on gelcoat and as you can see causes damage that is unwarranted. An adhesive remover should be tried first, if it doesn't work try the next step up in solvents. Acetone should only be used sparingly and as a last resort.
The second is 3M 5200. 5200 is an adhesive/caulking that is over used in place of caulking. This is a professional grade of caulk mainly to be used for its adhesive properties. I just shake my head when I see people reccomend it for installing transducers, outboard motor mount bolts and other items that sooner or later must come off.
T Party, sorry for the rant and I do feel your pain. Good luck with the repair
AC posted 03-03-2003 04:56 PM ET (US)     Profile for AC  Send Email to AC     
So what do you recommend instead of Acetone and 3M 5200? Lacquer thinner and 3M 4200?
Tom W Clark posted 03-03-2003 05:10 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
T Party,

I'm sorry to hear about your non-skid. Acetone is a powerful solvent. I do, however, take issue with Montauk's statement that it is too "hot" for use on fiberglass. This is simply not true.

I have used acetone extensively for over twenty years. It is especially good for cleaning dirt off of fiberglass. The best thing about acetone is it is so volatile (it evaporates very quickly) This means you can wipe something down and work it to the point you want it and then remove the excess and it will be dry in just seconds.

Many plastics will be attacked by acetone so you do need to careful about what you use it on. But you may feel free to wipe down your Whaler's hull without worrying about it melting the gel coat. It won't unless left in contact with the gel coat for an extended period of time as happened with T Party's cleaning rag and his non-skid.

Lacquer thinner, toluene, turpentine, alcohol, WD-40 gasoline, ect. all have their places as solvents. Acetone is for me the least offensive in terms of smell and the easiest to clean up afterward because it dries so fast. Always dry your rags in a outdoor open space after you are done using them, and do not use it to clean your hands.

hooter posted 03-03-2003 05:59 PM ET (US)     Profile for hooter    
And remember this, acetone may as well be dynamite if it encounters spark or flame. MUCH worse than gasoline due to its volatile personality. Ah do use it for reason's Mr. Clark recommends, but Ah'm friggin’ careful.
Montauk posted 03-03-2003 06:53 PM ET (US)     Profile for Montauk  Send Email to Montauk     
Acetone to clean dirt off gelcoat? Sorry but that is over use of a solvent, along with it being a carcigen. Do you use Chemical proof gloves when handling Acetone? It penetrates your skin and enters your blood stream without proper protection.
Yes, I use it to remove amine blush from fiberglass, I use it for removing stubborn grease or oil based spots from well cured gelcoat, but I never use it on boats that are less then 60 days old.
Perhaps I was not clear enough in my first post, but when someone says on the internet, "use acetone" they do not follow up with what the inherent dangers are and how to use it sensibly and that is exactly why this post started. I have been using Acetone for abut 30 years and some of these things I had to learn the hard way.

AC, When you are caulking your are not glueing something on, the mchanical fasteners hold it on. 5200 is a very strong adhesive if applied on properly cleaned surfaces, so strong that only heat will release it. You will need enough heat that it will damage the fiberglass under it.
I have seen gelcoat ripped right off the boat by 5200 used to mount towers. 4200 is one half the strength of 5200, a better choice in most circumstances. However, polysulfide caulks are oil and grease resistant and are reccomended for engine mounting bolts and similar applications, 4200 is not reccomended for use around oil and gasoline.
I am not against the use of the aforementioned products if they are used properly and for what they are intended.
Tom, I respect your opinion, but go back and read your third paragraph. Acetone will melt gelcoat when misused.

AC posted 03-03-2003 07:38 PM ET (US)     Profile for AC  Send Email to AC     
Do you like 3M 4200 for sealing thru-hull fittings, or something else (considering one may replace the seal once every 5-10 years due to deterioration of the O-ring and sealant)?
Tom W Clark posted 03-03-2003 09:19 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

I respect your opinion too. I also think reasonable minds can disagree and that’s OK. This may be one of those times.

I have reread the third paragraph of my post above and I have reread your posts. In fact, I have reread this whole thread quite carefully and I have chosen my words very carefully. I qualified my statement about acetone not hurting gel coat very clearly and deliberately (even using bold so it couldn’t be missed). I stand by what I have said.

There seems to be this old wives tale that if you wipe an acetone soaked rag on your Whaler the gel coat will be dissolved. This is not true. You can scrub the hell out of your Whaler with an acetone soaked rag and the gel coat will not be harmed.

T Party apparently left an acetone soaked rag in his boat for five days and the gel coat was attacked. I believe him and I think it is good that he has pointed out the danger of allowing such a thing to happen.

I do not think T Party’s boat is less than 60 days old. Do you? While I have owned two Whalers that were bought new (and presumably were less than 60 days old because they were special ordered by me) I don’t recall ever using acetone on them. So I cannot speak to the experience of using acetone on “green” gel coat.

I have never left an acetone soaked rag in contact for any period of time with any of my Whalers or the hull of any other boat I have ever owned. My experience with acetone would make me think that something bad might happen if I were to do so. T Party’s experience seems to reinforce this

If I have a smear of road tar on my hull or if I had just removed the decals from the side of the hull and needed to clean up the adhesive residue, I guarantee you acetone will be the first thing I grab. Dab some on a rag or paper towel and have at it. Cuts that stuff like crazy and evaporates away in no time. It does no harm to the gel coat.

Yes, I often do wear chemical resistant gloves (acetone will melt most conventional disposable gloves) and I certainly do not recommend breathing the fumes, drinking it, snorting it or bathing in it. The stuff stinks. It is NOT, however, a known human carcinogen.

And I'm with you on the 3M 5200. But please don't make the silly statement that I have heard so often that if you seal a little screw with 5200 you will not be able to remove it. That's not true either. It's the bedding a surface that will result in the permanent adhesion of a fixture to fiberglass.


3M 4200, 3M 101 and Sika 231 are all good, lower adhesion sealants. Run-of-the-mill silicone is good for motor mounting bolts.

T Party posted 03-03-2003 10:35 PM ET (US)     Profile for T Party    
Glad I could get a good discussion gonig around here. Just to clarify, I was using the acetone in small amounts, with gloves on, to remove some grease and stick-on adhesive after removing the Morse control and the Teleflex helm from my 1977 Montauk. They looked like original equipment and original installation - in other words, I was trying to remove 25 year old goo and preparing the surface for adhesion of a new black plastic sheet. The console looks great now with a new helm, new black plastic and a new Morse control.

I basically forgot that I had tossed the rag into the stern when the cloudburst started and I quickly covered the boat. I was surprised by the damage because I thought the acetone would have evaporated (we've had a couple warm days here and my boat cover is dark blue and gets warm), and it's not like it was soaked in the stuff in the first place (just a small area for wiping). I certainly learned my lesson, and hope others will learn from my mistake.

Clearly, acetone is not to be trifled with, and I considered myself a relatively careful user of the stuff even before this happened. I would not hesitate to use it again - but I will pay greater attention to what I do with the rag (I probably won't use it on a rag again - paper towel) and will clean up any spills quickly and thoroughly.

Montauk posted 03-03-2003 10:42 PM ET (US)     Profile for Montauk  Send Email to Montauk     
AC, I agree with Tom on his choice of sealants, and also agree that little screws sealed with 5200 are easy to remove. If you are bedding something you would like to remove down the line use a sealant, if it is a piece that will be permanent use an adhesive/caulk like 5200.
Montauk posted 03-04-2003 10:28 AM ET (US)     Profile for Montauk  Send Email to Montauk     
T Party, are you sure your boat has not been painted in the area where the damage occurred? After reading your second post it does not sound like you misused the acetone, I had assumed that you threw a sopping wet rag in the stern. The holes where the foam was pumped into the boat are about silver dollar size, and on my boat they are crudely filled with gelcoat which has a few cracks in it. If you have a digital camera I would like to see a picture if possible. I do not think that a small amount of acetone could remove the non-skid.
I would like to offer an apology to the forum members for stating that acetone is a known carcinogen. I did some research on the net and various reports show that I am wrong. My can of acetone from Ace Hardware does state in the warning label, "Use of this product will expose you to benzene which is known to cause cancer."
I would like to suggest using 3M General Purpose Adhesive Cleaner -#08984 as substitute for removing adhesive, silicone, wax, grease, tar and oil. It does take a little more time to use but is far safer to you. The main ingredient is Naptha which you can buy in gallons also and is cheaper than the 3M product. The same care as used with acetone in the disposal of rags and skin protection should be taken. Spontaneous combustion is a possibilty also, spread the rags outside to dry as it does not evaporate as fast as acetone.
frank_king posted 03-04-2003 06:51 PM ET (US)     Profile for frank_king  Send Email to frank_king     
tw i agree with you.

acetone was the only thing that would take the glue off that was left on my boat when i pulled the boston whaler stickers off. i have a 1981 montauk and i did have some paint thinner to try on the glue first. that was a joke, so i got out some acetone and went to work. i had to soak the glue and then quickly scrape it off before it dried out. i had to do this for an extended amount of time say 25-30 min per side. i know first had that acetone can be used on fiberglass and gelcoat. as long as the person using it is careful.

T Party posted 03-06-2003 05:40 PM ET (US)     Profile for T Party    
It's possible that I parked a box on top of the rag and that the box held the acetone against the floor (and also may have slowed down evaporation). There's no paint there - just gelcoat, and it's in the non-skid. I'm actually not sue, because I didn't discover the damage until after I'd taken everything out of the boat and had been working on it again the next week. The lesson here is to be sure you account for all your rags if you've been using acetone, and don't leave them in contact with the gelcoat.
lhg posted 03-06-2003 06:04 PM ET (US)     Profile for lhg    
I use mineral spirits for all of the above cleaning issues, and it works fine with no damage at all.
Arch Autenreith posted 03-07-2003 03:29 AM ET (US)     Profile for Arch Autenreith  Send Email to Arch Autenreith     
I have a piece of fiberglass w/gelcoat from my Montauk from the repair I did a couple years ago. I'm going to put an acetone-soaked rag on it and see what happens. I'll let you know.
tarbaby posted 03-07-2003 07:31 AM ET (US)     Profile for tarbaby  Send Email to tarbaby     
Arch, to make an accurate test on your piece of fiberglass, it needs to be placed at the bottom of a box or something where the vapors can have a chance to settle like they did on the floor in Johns boat with the cover on. I think you will not get the same results if you place a rag on a piece of fiberglass that is free standing in your shop. Let us know how your experiment turns out. Shay
Arch Autenreith posted 03-07-2003 09:17 AM ET (US)     Profile for Arch Autenreith  Send Email to Arch Autenreith     
Great minds think alike, tb. I'll be doing it this weekend and will see what happens come Monday.
witsendfl posted 03-07-2003 10:51 AM ET (US)     Profile for witsendfl  Send Email to witsendfl     
Be real careful with ACETONE. It works great for cleaning gelcoat. You can even dilute gelcoat when you spray it on. Those little aeresol bottles that you buy NAPA work great when you dilute the gel. Just use it as a LAST resort when cleaning. There was a statement about cleaning your hands with it. At least don't pour it all over your hands. That stuff is absorbed through your skin and goes right to the limp knodes under your arms. I am not saying it is a carcinogin (sp). I use it on a rag to clean specfic area but try not to let it touch my skin. Just be careful

On the gelcoat issue. Be careful of "SPONTANEOUS COMBUSTION" when leaving rags out expoxed.

witsendfl JimK

NEVER SCARED posted 03-07-2003 03:59 PM ET (US)     Profile for NEVER SCARED    
I used 5200 to seal the gap between the floor panel and hull. The area was clean and dry when applied. Months later I was disappointed when the 5200 pulled away all by itself! Everywhere I used it, I could remove it with 2 fingers. That $2.00 kitchen and bathroom sealer had way better adhesion.
Montauk posted 03-07-2003 05:31 PM ET (US)     Profile for Montauk  Send Email to Montauk     
Never Scared,
I can assure you that 5200 will not release as easy as you have experienced if properly prepped and not exposed to gas and oil while curing. Cure time is approximately 7 days at 75 degrees and at 6o degrees, closer to 14 days. Did you abrade the fiberglass surface and then wipe with a solvent?
You would be better off using a sealant(polysulfide) that is resistant to oils and gasoline on floor panels. 5200 is a polyeurethane and is classified as a Adhesive/sealant.

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