how do you remove minor barnicals on gel coat
- Thread starter Dil
- Start date
Those look like they are above the waterline. (?). Also look like something other than barnicals. Scrape them off using a plastic scraper so as not to scratch the gel-coat. That's all I got at the moment.
I've been using a 1-1/2" wide very sharp wood chisel to remove vinyl and paint from gel coat. There is no reason why it wouldn't take the barnacle and any residue right off. I know that most would be horrified, but I can testify that it is almost impossible to set it on edge in a manner that would gouge the gel coat. I can put full pressure on it and it simply glides right across the gelcoat and removes all foreign substance with the least amount of effort. It takes adhesive off pretty effectively and lately, I've found that it is my last resort in shaving off that final thin layer of acrylic polyglo that stubbornly resists ALL chemical application. Try it gingerly if you must. I've found that you would have to be very uncoordinated to actually turn that blade so that it gouges.
BTW, I've never found a plastic scraper that can remove anything effectively. The plastic "razor blades" are an absolute joke and a complete waste of time. Don't use thin razor blades, they do gouge very easily. The secret is that a wood chisel is extremely stiff and you would have to purposely set it on edge so that it gouges. Set flat, the blade will not penetrate the gelcoat while at the same time it gets right under any foreign substance. You'd have to set it at a very high angle to actually penetrate the gelcoat, and then it isn't effective for scraping either. It's pretty easy to get the exact right angle and it is non-damaging to the gel. The irony is that I would never actually use it on wood, unless I intended to chisel the wood! It's the only way I was able to get a painted boot stripe off without damaging the underlying gel coat. With that aggressive use, I do have to aggressively polish the gelcoat to get the color of the boot stripe restored, but I had no gouges to deal with. (I have no idea why the P.O. painted the boot stripe - he must have thought a darker blue would look better, but he only made a mess that had to be removed).
BTW, I've never found a plastic scraper that can remove anything effectively. The plastic "razor blades" are an absolute joke and a complete waste of time. Don't use thin razor blades, they do gouge very easily. The secret is that a wood chisel is extremely stiff and you would have to purposely set it on edge so that it gouges. Set flat, the blade will not penetrate the gelcoat while at the same time it gets right under any foreign substance. You'd have to set it at a very high angle to actually penetrate the gelcoat, and then it isn't effective for scraping either. It's pretty easy to get the exact right angle and it is non-damaging to the gel. The irony is that I would never actually use it on wood, unless I intended to chisel the wood! It's the only way I was able to get a painted boot stripe off without damaging the underlying gel coat. With that aggressive use, I do have to aggressively polish the gelcoat to get the color of the boot stripe restored, but I had no gouges to deal with. (I have no idea why the P.O. painted the boot stripe - he must have thought a darker blue would look better, but he only made a mess that had to be removed).
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A putty knife works pretty well. Clean up the residue with some diluted Muriatic acid (cheap) or Mary Kate On/Off (expensive for basically the same stuff).
In my experience, a putty knife also is ineffective in removing foreign material. The problem with a putty knife is that it is not sharp enough and it is too flexible. What works best for me is the chisel because it is very sharp and very stiff. When you really need to press, the putty knife bends and flattens the angle so that the dull blade can't get under the material (instead it just glides right over). You need a sharp blade set at just the right angle with pressure. The blade will glide right over the gel and the sharp edge shears off everything, including the residue. I can make shorter work on the residue with a sharp blade than I can with any solvent.
Before attacking with a 6 inch taping knife (used for drywalling).
After scraping, acid washing, and power washing.
After scraping, acid washing, and power washing.
you have so few... I'd wet a sponge with vinegar and then lay it on the barnicle and let it sit for a while. The shells are calcium carbonate and dissolve in vinegar. Maybe secure the sponge with some masking tape so you don't have to stand there... go have a beer while the vinegar does its thing and it will be gone an hour later.
Acid wash. You can use muriatic acid from the hardware store or dilute hydrochloric acid. CLR or On and Off are commercial products to do this.
Stomach Acid, Muriatic Acid and Hydrochloric Acid are synonyms. It will also do the job for sure.... BUT!....HCl attacks metals so if you go that route, don't let it touch any of your stainless.
Acid is a term that means a material will increase the concentration of free protons in water... but the reactivity of acids vary a LOT. All concentrated forms of Acid are harmful but in dilute form there are still some issues that should be considered when choosing an acid for a particular job...
- Hydrochloric Acid (a.k.a. Muriatic Acid, a.k.a. Stomach Acid) will attack metals but is relatively benign on skin and if dilute will also do relatively less harm on cloth than some other acids.
- Hydrofluoric Acid is one of the few acids that will attack glass. In dilute form, it is relatively benign on metals. It is used to make frosted glass signs etc. It is also the active ingredient in wheel rim cleaners found at AutoZone etc. It will dissolve the aluminum silicate grit that gets embedded in the rims. It is REALLY bad on your lungs. I find it shocking that any bubba can buy this stuff at AutoZone or Advanced Auto.
- Sulfuric Acid (a.k.a. battery acid) is VERY aggressive on organic materials (i.e. your skin and eyes) but is relatively benign against metal. It will destroy your clothing, sails, bimi etc. Keep it away from ALL fabric (and your eyes).
- Carboxylic Acids are a class of acids that include "biological acids" such as vinegar, oxalic acid, citric acid etc. Carboxylic Acids are responsible for the sour taste of many foods and candies. Some are toxic so I don't recommend tasting them unless you know some biochemistry.
- Vinegar and Citric Acid are very good at dissolving calcium carbonate
- Oxalic Acid will also dissolve CaCO3 but it is especially good at chelating iron ions in the +3 oxidation state (i.e. rust) and is the main ingredient is rust remover. It can be purchased in many products. My go-to is Barkeeper’s friend-Liquid. It is toxic so don't make margaritas with it. Oxalic acid is also a strong oxidizer and works wonders on tannin stains (like the scum line you get at the water line).
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That should also work,
The active ingredient in Lime-Away is hydrochloric acid and a quaternary amine surfactant (i.e. soap).