Respecting the advice of Michael Stoops in my previous post of Gelcoat Restoration not lasting, I’m attempting to avoid wet sanding of the gelcoat. However, we’re stuck again. After repeated power application of another new section with M91 & M67 deep stains are not being removed. The gelcoat is significantly improved by the compounding, but not as good as it can or should be.
On a test patch, following M91 & M67, for those stubborn stains, I have wet sanded with 1,000 thru to 2,000 grit. The stain was removed - with relative ease. Another M67 following the sanding and it looks fantastic.
The actual composition of the stain is uncertain – It ranges from yellow, to brown, to black – generally originating from rain running off the deck which was filthy including industrial atmospheric pollutants, general road type dirt in the atmosphere, and rust type stains from stainless steel fitting.
If 91 & 67 is not working, and wet sanding does work but is not recommended, would the use of chemicals be a better alternative to wet sanding?
My local paint shop has just started carrying a product by CRC called MaryKate. The product contains, Hydrocloric Acid, Phosphoric acid, Ethoxylated nonylphenol and Oxalic acid – One nasty mix ! I have not applied this to the hull hence have no idea is it will work – assuming it will – as they say it will – Is this (or any other chemical) a less destructive method than wet sanding an aged gelcoat which is desperately attempting to shine ?
On a test patch, following M91 & M67, for those stubborn stains, I have wet sanded with 1,000 thru to 2,000 grit. The stain was removed - with relative ease. Another M67 following the sanding and it looks fantastic.
The actual composition of the stain is uncertain – It ranges from yellow, to brown, to black – generally originating from rain running off the deck which was filthy including industrial atmospheric pollutants, general road type dirt in the atmosphere, and rust type stains from stainless steel fitting.
If 91 & 67 is not working, and wet sanding does work but is not recommended, would the use of chemicals be a better alternative to wet sanding?
My local paint shop has just started carrying a product by CRC called MaryKate. The product contains, Hydrocloric Acid, Phosphoric acid, Ethoxylated nonylphenol and Oxalic acid – One nasty mix ! I have not applied this to the hull hence have no idea is it will work – assuming it will – as they say it will – Is this (or any other chemical) a less destructive method than wet sanding an aged gelcoat which is desperately attempting to shine ?
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