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Old 23-01-2020, 20:21   #31
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Re: Interior gelcoat with patchy yellow stains

@fruityloop8,

With the oxalic acid, it will run, unless you use a gel type preparation. Probably brick cleaner is the cheapest source. The label may say which acid you're using. After it has been on for a while, rinse with fresh water. Or, if you're concerned about an acid residue (it will bleach fabrics, and eat holes in some), use "some" baking soda in the rinse water, say 1 tablespoon to 1 qt. It's neutralized when it quits making bubbles.

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Old 26-01-2020, 02:10   #32
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Re: Interior gelcoat with patchy yellow stains

I have a 2003 B36, same thing. I got yellowing in various spots. It’s as if the manufacturers used some cleaner or caulk that eventually bled. So, when you find a resolve i’ll Be thrilled to try same. Until then, there’s plenty of challenges awaiting for me...
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Old 27-01-2020, 06:52   #33
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Re: Interior gelcoat with patchy yellow stains

Quote:
Originally Posted by fruityloop8 View Post
Hi,
Firstly - first post of many to come from me!

I am about to put an offer in for a Bavaria 38, boat is in great condition except for one thing... the headliner (in this boat not fabric, just the glass & gelcoat in white) has ugly yellow patches all over the interior.

Current owner doesn't know what it is, was like that when he bought it. The original owner was a live aboard and heavy smoker (boat doesn't smell like an ashtray), so it could be that. Current owner has tried to clean (don't know with what) with no success.

Anyone have any ideas what it may be?

And I guess my 2 options would be:
1. Try bleach / gelcoat white cleaner products
2. Repaint in white. I'm not against doing this, but the headliner has a textured pattern to it. If I have to sand back the gelcoat for the primer/paint, I run the risk of making the texture somewhat distorted and ugly...

Many thanks for the help!
Cheers
Try Acetone- I encountered a similar issue & it worked like Magic. Wear gloves though, and close all the hatches, as you get a much better contact buzz😛
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Old 27-01-2020, 06:58   #34
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Re: Interior gelcoat with patchy yellow stains

Hi All, CaptVR here. I've seen this in many, many boats over the years surveying. I would put my best guess, styrene migrating to the surface of the resin that is used in the layup. It's chemical, not organic so bleaches and cleaners will not work. I personally have used mild acids and alkali's to no avail. Over my 73 years, 55 of those building and refurbishing boats, nothing will remove this yellow staining, it literally is in the makeup of the structure. You either live with it or paint it. Being on gelcoat, you can skip the primer and just dewax and scrub down with an abrasive Scotch Bright pad and paint with a good grade two part polyurethane. Make sure and strictly use safety procedures in using polyurethanes, they are quite dangerous if safety is not adhered to.
On the positive side, there is no degradation to strength due to this styrene migration. Won't chip, won't flake, won't crack, just looks funky .
Hope this might give you some insight.
Capt. Vince Rakstis, Ret. St.Pete., Fl.
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Old 27-01-2020, 07:22   #35
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Re: Interior gelcoat with patchy yellow stains

First process in the "process of elimination..." 1: use a degreasing spray just to be sure no oil on the surfaces. 2 apply medium strength oxalic acid (or better a combo of OA and LA awesome cleaner) spray on let sit them wipe off with a cloth. No effect, clean cloth with Lacquer thinner....(acetone does not dissolve some materials much at all)
If nothing is changing, find some rubbing compound without wax and do a good rub and see if anything responds. If all else fails a light sanding with 220 wet sandpaper and you can paint with petit ezyCabin Kote which is a very tenacious water based polyurethane highly resistant to mildew and mold.....(you really dont need to sand but 220 does an adequate job for insurance)
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Old 27-01-2020, 10:18   #36
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Re: Interior gelcoat with patchy yellow stains

Quote:
Originally Posted by CF32907 View Post
Hi All, CaptVR here. I've seen this in many, many boats over the years surveying. I would put my best guess, styrene migrating to the surface of the resin that is used in the layup. It's chemical, not organic so bleaches and cleaners will not work. I personally have used mild acids and alkali's to no avail. Over my 73 years, 55 of those building and refurbishing boats, nothing will remove this yellow staining, it literally is in the makeup of the structure. You either live with it or paint it. Being on gelcoat, you can skip the primer and just dewax and scrub down with an abrasive Scotch Bright pad and paint with a good grade two part polyurethane. Make sure and strictly use safety procedures in using polyurethanes, they are quite dangerous if safety is not adhered to.
On the positive side, there is no degradation to strength due to this styrene migration. Won't chip, won't flake, won't crack, just looks funky .
Hope this might give you some insight.
Capt. Vince Rakstis, Ret. St.Pete., Fl.
This. We have a 1976 boat with a gelcoated interior liner. When we bought the boat 10 years ago, we noticed an unpleasant smell. We thought it was the head, holding tank or pipes. Not so. It was some kind of breakdown product of the gelcoat. The interior has a strongly patterned "leather" surface.

Over the course of three years we painted the interior and now the boat has no smell.

Dewaxing as per Capt. Rakstis is important. Most interiors, even after 30 or more years have significant portions of mold wax still present. Originally I used Interlux solvent wash 202. DON'T use this. It is horrible to work with, flashes off fast and takes many cycles to shift the wax fully. (We used it in the interior of the V-berth and it was nasty - working in the full protective gear.)
My recommendation is to use Interlux Fiberglass Surface Prep (YMA601) this is much more pleasant to use and faster. You still need to follow the safety sheet.

Light sanding with 320 grit on the smooth surfaces. Wipe everything with solvent.

Then we painted with Interlux Brightside. We didn't use the primer, just rolled and tipped, straight onto the interior gelcoat, including the patterned areas. As long as you're using a similar color, two coats is plenty.

I like Brightside so much as a paint, that I've started using it on my garage doors at home!
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Old 27-01-2020, 11:15   #37
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Re: Interior gelcoat with patchy yellow stains

Quote:
Originally Posted by fruityloop8 View Post
Hi,
Firstly - first post of many to come from me!

I am about to put an offer in for a Bavaria 38, boat is in great condition except for one thing... the headliner (in this boat not fabric, just the glass & gelcoat in white) has ugly yellow patches all over the interior.

Current owner doesn't know what it is, was like that when he bought it. The original owner was a live aboard and heavy smoker (boat doesn't smell like an ashtray), so it could be that. Current owner has tried to clean (don't know with what) with no success.

Anyone have any ideas what it may be?

And I guess my 2 options would be:
1. Try bleach / gelcoat white cleaner products
2. Repaint in white. I'm not against doing this, but the headliner has a textured pattern to it. If I have to sand back the gelcoat for the primer/paint, I run the risk of making the texture somewhat distorted and ugly...

Many thanks for the help!
Cheers
Have you looked at other board of the same year and model. It may have had a glued fabric headliner that was stained from the smoker and taken out. That might have been done by the owner who smoked to get the smell out. If that is the case you know it is an adhesive based stain. That would help you narrow down how to remove it. Keep in mind 3 things can happen. You can use a cleaner and remove the stain, sand and repaint or just live with it.
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Old 27-01-2020, 14:35   #38
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Re: Interior gelcoat with patchy yellow stains

Have you considered having someone from an upholstery shop cover it with the fabric of your choice?
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Old 27-01-2020, 14:43   #39
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Re: Interior gelcoat with patchy yellow stains

Good morning,
It appears to me to be nothing more than poor quality application of gel coat- I have similar condition with my ETchells that has had many repairs over its life and when I asked 2 specialists they both said it related to styrene problems - if you simply google yellow gel coat stains perhaps you will find help BUT they both said can only be repaired by repainting via gel coat or 2 pac for a long term job .

Peter
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Old 27-01-2020, 15:09   #40
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Re: Interior gelcoat with patchy yellow stains

Quote:
Originally Posted by fruityloop8 View Post

Some good suggestions of products to try. Is anyone familiar with what the stain may be? Anyone bought a boat from a heavy smoker previously?
Mold. Our boat does the same thing, we bought it new, and we don't smoke. The interior of our boat is gelcoat, rolled on since it's the inside so it's not super smooth. The lack of smoothness is what allows the mold to take hold. We've bleached it with a 50% water 50% bleach solution and it goes away, but then it comes back in 6 months to a year, depending on where we are. The wetter the climate, the quicker it comes back. In some areas, I've sanded and re-rolled with new flowcoat (gel coat with wax in it) and then it does not happen. The smoother and slippier the surface, the less likely for mold to be able to attach. Also note that bleaching and treating gelcoat with chemicals like acetone damages it - the more times you do that, the more porous it becomes - you'll actually see the rag turing white as it dissolves the gelcoat. The more gelcoat you remove to make it nice and white, the faster the yellow mold just comes back. So your best choice would be to sand it, re-roll the gelcoat with a superfine mohair roller, and never bleach or acetone it afterwards. Gelcoat can be rolled on in mulitple layers to reach a minimum thickness, and then hand sanded back to a super fine glossy finish using guidecoat, sanding blocks, and wet sandpaper, starting with a rough grit and working towards a super fine 1600 grit. It's very time consuming, but you'll be rewarded with a beautiful durable finish, and large biceps.
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Old 27-01-2020, 19:28   #41
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Re: Interior gelcoat with patchy yellow stains

Stains like you show are IN the fiberglass gel coat, not on the surface. If you are lucky, the stain is something like rust which can be cleaned off with CLR. If you are not lucky, and the stain is carbon and tars from smoking that have penetrated into the pigments of the gel coat, you may never get them out. Carbon simply has no solvent. You will be stuck with resurfacing the surfaces in question should it a carbon stain that has worked its way into a porous gel coat.
I have seen gel coats that were quite porous and stains easily penetrated them. If the stains are easily bleached out like mold, 1/4 strength Clorox will work - use lots of ventilation as the smell is awful. Your first job is to identify the stain and then you can find a solvent - if there is one. Do not use harsh solvents like MEK or carb cleaner as you will dissolve your gel coat. I would not suggest or use paint on the fiberglass interior of a boat. Paint has a hard time sticking to old gel coat and you do not want to end up with flaking paint all over the interior. For a renewed gel coat, use an aggressive solvent to soften the surface after sanding and apply either epoxy gel coat or a similar bonding resin with a high titanium dioxide pigment content and sufficient wax float to produce a high shine. This is equivalent to sealing the hull under water and you want a finish that is hard, nonporous, and chemically resistant when all is done. Consult people in the business for the right type of resin to use. I have had good success with a high quality epoxy rolled on. Brushing makes a mess. Make sure the cure time is long enough to work the entire panel before setting occurs. If there are surface irregularities or waves, you can apply the epoxy with a textured roller and achieve a nice finish. When you are done and the surface is fully cured, you can prevent future stains with a high quality automotive wax liberally applied and well buffed. Fixing things is never easy but messing up the job makes it even harder. Do it right, once. When in doubt, consult an expert.
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Old 27-01-2020, 20:23   #42
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Re: Interior gelcoat with patchy yellow stains

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Stains like you show are IN the fiberglass gel coat, not on the surface. If you are lucky, the stain is something like rust which can be cleaned off with CLR. If you are not lucky, and the stain is carbon and tars from smoking that have penetrated into the pigments of the gel coat, you may never get them out. Carbon simply has no solvent. You will be stuck with resurfacing the surfaces in question should it a carbon stain that has worked its way into a porous gel coat.
I have seen gel coats that were quite porous and stains easily penetrated them. If the stains are easily bleached out like mold, 1/4 strength Clorox will work - use lots of ventilation as the smell is awful. Your first job is to identify the stain and then you can find a solvent - if there is one. Do not use harsh solvents like MEK or carb cleaner as you will dissolve your gel coat. I would not suggest or use paint on the fiberglass interior of a boat. Paint has a hard time sticking to old gel coat and you do not want to end up with flaking paint all over the interior. For a renewed gel coat, use an aggressive solvent to soften the surface after sanding and apply either epoxy gel coat or a similar bonding resin with a high titanium dioxide pigment content and sufficient wax float to produce a high shine. This is equivalent to sealing the hull under water and you want a finish that is hard, nonporous, and chemically resistant when all is done. Consult people in the business for the right type of resin to use. I have had good success with a high quality epoxy rolled on. Brushing makes a mess. Make sure the cure time is long enough to work the entire panel before setting occurs. If there are surface irregularities or waves, you can apply the epoxy with a textured roller and achieve a nice finish. When you are done and the surface is fully cured, you can prevent future stains with a high quality automotive wax liberally applied and well buffed. Fixing things is never easy but messing up the job makes it even harder. Do it right, once. When in doubt, consult an expert.
Hi All, CaptVR here again, please look at my previous blog. It will give you good advice with facts to back it up. This blog has virtually no accurate info and most is totally wrong and not factual at all. It amazes me the inaccurate supposition that folks post that is totally guessing at best. Carbon and tars from cigarette smoke is easily cleaned. Where they got the idea that paint does not stick to old gelcoat is just ludicrous, there are many type of paint that stick tenaciously to old gelcoat, fact, you can paint directly on properly prepaired gelcoat without primer or bonding agents . With the proper polyurethane, you can roller and tip the paint and it will come out looking like a spray job, roll and tipping paint jobs have been around for 50 years. I know, I've done it for fifty years. No such thing as high quality / low quality epoxy. Systems Three or Gougoen Brothers (most expensive) is no better than the epoxy from your local supplier. The one thing I agree with, find a local supplier and pick their brains, Most FRP / Esters and Epoxies Sales have folks that know there business, get all the info you can before starting. Just thought I'd throw this in, dewaxing wash has acetone, MEK, alcohol mineral spirits blended to wash gelcoat to remove molding waxes, this mix won't even soften gelcoat, but it does remove waxes from original molding to the last Carnuba's applied. Painting is great, it does adhere if all is areas are properly preped. Interior paint you can use about any quality paint for top-sides. Exterior I recommend two part polyurethane. Do not use epoxy paint outdoors, the finish will not stay bright and shinny more than a year or so, ultraviolet is very ruff on epoxy finishes. OH, that's something else, no such thing as epoxy gelcoat!!!!!!!!!
You can ad gelcoat and epoxy pigment color to epoxy for color, but there is no gelcoat as for polyester or vinylester. Hope this throws a little more insight on this subject.
I've built 6 boats, two airplanes and refurbished maybe a hundred boats in the 55 years I've worked in this industry. I was a SAMS surveyor for over 20 yr's.
Capt Vince Rakstis, Ret. St.Pete, Fl.
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Old 28-01-2020, 03:33   #43
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Re: Interior gelcoat with patchy yellow stains

I removed stains just like that on a fibreglass inner liner once. I used general purpose thinners and it took about 10 seconds. I looked really bad and other things like bleach and OA did nothing, but the thinners worked instantly!
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Old 28-01-2020, 06:03   #44
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Re: Interior gelcoat with patchy yellow stains

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Originally Posted by CF32907 View Post
Hi All, CaptVR here again, please look at my previous blog. It will give you good advice with facts to back it up. This blog has virtually no accurate info and most is totally wrong and not factual at all. It amazes me the inaccurate supposition that folks post that is totally guessing at best. Carbon and tars from cigarette smoke is easily cleaned. Where they got the idea that paint does not stick to old gelcoat is just ludicrous, there are many type of paint that stick tenaciously to old gelcoat, fact, you can paint directly on properly prepaired gelcoat without primer or bonding agents . With the proper polyurethane, you can roller and tip the paint and it will come out looking like a spray job, roll and tipping paint jobs have been around for 50 years. I know, I've done it for fifty years. No such thing as high quality / low quality epoxy. Systems Three or Gougoen Brothers (most expensive) is no better than the epoxy from your local supplier. The one thing I agree with, find a local supplier and pick their brains, Most FRP / Esters and Epoxies Sales have folks that know there business, get all the info you can before starting. Just thought I'd throw this in, dewaxing wash has acetone, MEK, alcohol mineral spirits blended to wash gelcoat to remove molding waxes, this mix won't even soften gelcoat, but it does remove waxes from original molding to the last Carnuba's applied. Painting is great, it does adhere if all is areas are properly preped. Interior paint you can use about any quality paint for top-sides. Exterior I recommend two part polyurethane. Do not use epoxy paint outdoors, the finish will not stay bright and shinny more than a year or so, ultraviolet is very ruff on epoxy finishes. OH, that's something else, no such thing as epoxy gelcoat!!!!!!!!!
You can ad gelcoat and epoxy pigment color to epoxy for color, but there is no gelcoat as for polyester or vinylester. Hope this throws a little more insight on this subject.
I've built 6 boats, two airplanes and refurbished maybe a hundred boats in the 55 years I've worked in this industry. I was a SAMS surveyor for over 20 yr's.
Capt Vince Rakstis, Ret. St.Pete, Fl.
Listen to the voice of experience, ladies and gents! Paint it a wonderful thing when gelcoat has degraded to the point of being unsightly.

Also, follow the manufacturer's literature carefully; instructions for use and safety precautions. They don't want you to have a bad experience or hurt yourselves.
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Old 28-01-2020, 07:20   #45
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Re: Interior gelcoat with patchy yellow stains

Good morning all, it’s Marc from Robin’s Nest, Morgan OI 41. If the stains are nicotine use Top Job to remove. If Rust use The marine acid rust remover for fiberglass, I forgot the name. More than likely the jellcoat is just yellowed. We painted our two heads ceilings using the marine semigloss white from Rust o leum purchased at Home Depot or Lowes. Ours is textured as well and a paint pad does a great job. This is the square plastic pad used to cut in the corners and ceiling when painting with a roller. The nap is about 1/4 inch. Clean with TSP or acitone first.
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