Author Topic: Carbon fiber mast maintenance and coating / painting  (Read 201 times)

PurpleOnion

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Carbon fiber mast maintenance and coating / painting
« on: March 17, 2020, 06:11:54 PM »
Short question:
Does anyone have clear guidance on how to maintain a carbon mast?  My specific issue right now is the clear coat coming off and Iíd like to re-coat or paint it properly.

Long set of questions and anecdotal information gathered off the web:
The clear coat on my C-Tech carbon mast is showing signs of wear and Iíve spent a few weeks trying to figure out how to address it. Unfortunately, I didnít find much definitive information.  In fact, most of it is anecdotal.  Hereís a summary of the many differing pieces of advice Iíve found on the wonderful Internet.  Some of it is obvious, but Iíve never found all of the information in one spot.  Iím posting it here to share and to gain any feedback from this group that could increase my understanding and, possibly, help others. I welcome additions, corrections, clarifications.  As youíll see some of it is contradictory or of questionable merit.

What Iíve read is that the carbon fiber itself is relatively good resistance to UV, however the epoxy resin surrounding it does breakdown due to exposure to UV.  I didnít find anything definitive regarding how quickly, but anecdotes suggest itís rather slow and can be measured over years rather than weeks or months.

This is heavy on conjecture, but Iíve read it in multiple places.  Manufacturers of the carbon fiber products tend to clear coat it because itís cool to see carbon fiber and because the clear coat is supposedly lighter weight than any of the epoxy paints that would otherwise be used to cover it.  I canít speak to the accuracy of this one, but it is one of a few arguments made by people who believe that clear coat is suboptimal from a UV protection and durability perspective.

One post on this forum states that C-Tech coated their masts with DuPont 696 automotive clear coat.  I do not know what Forte coats their masts with.

Some clear coats have UV inhibitors in them.  Some do not.  Sample clear coats with UV inhibitors include Awlgrip, Interlux Perfection Plus, Duratec Sunshield, and a variety of lower cost options geared towards cars.

People claim that opaque paints offer significantly more UV protection.  Sample opaque paints include Awlgrip, Interlux Perfection Plus, and a variety of lower cost options geared towards cars like Duplicolor, Rust-Oleum and many others.

People claim that clear coats tend to break down over a 2-5 year period.  People claim that opaque paints like Awlgrip and Interlux Perfection tend to last 10 years or more.

Lighter colored opaque paints are better at revealing the various dings and scratches that occur and make it easier to touch up.

Lighter colored paints like white or silver keep the mast cooler and could reduce stress between the epoxy and carbon fiber in the mast as well as the coating because they are likely to be impacted differently by elevated temperatures.

Whether heat is an issue or not is an area of debate. Hereís some of what Iíve read.  People have stated that most quality carbon fiber products are baked at 250 degrees F or higher.  Some people believe that this means that all is fine because a clear coated black carbon mast heated by the sun will never approach this temperature.  Other people are more cautious and invoke the stress argument about different materials noted above. Considering that there are carbon fiber hoods over high performance engines in cars, itís hard to fully buy into, but I have no idea if anything unique is done for those parts.  People suggest that raised masts are significantly cooler than a mast laid on the ground or similar due the cooling effect of the breeze.  I donít recall ever noticing the temp of the clear coated mast.

Painting a mast an opaque black would block the UV, but subject it to similar heat issues as clear coat without whatever ďcoolĒ is associated with the weave look.  Again, I canít speak to whether this is an issue.

Even more anecdotes suggest that masts in tropical and other high sun areas tend to paint masts white for protection.  Thereís no actual data to support this.  Just hearsay from the all knowing Internet.

The tops of spreaders may require extra protection (e.g. an extra coat or an opaque paint) as they are always facing up towards the sun. This is supported by viewing my spreaders, but I have no scientific evidence beyond appearance and the notion that the tops are never struck by anything, but have weathered much worse than the base of the mast where the blocks on the jib clew regularly bang away at the mast.

The above said, Iíve never heard / read about a carbon fiber mast breaking due to UV damage or heat related issues.  Maybe others have.

Regarding paint / coating, the general consensus of opinions is:
- Clear coats tend to require recoating more frequently.  Some do it annually, others do it as required and suggest 2-6 year intervals
- Epoxy paints last 10 years or more.
- Lighter colored paints reflect more heat and allow you to see where dings and scratches are making it easier touch up.
- 2 part epoxy paints last much longer and are stronger than 1 part. Again, thereís little science behind durations and strength, but thereís little debate that 2 part is stronger.  Commentary suggests that 2 part will last 10+ years vs. 2-4 for 1 part.
- Thinner is required to help the paint or clear coat spread.  Ratios vary by product, but, in general, greater thinning is required for spraying the paint vs. brushing.
- Drying time is greatly influenced by heat and humidity.  A few products I looked at include drying time by temperature and some do not recommend usage below 50 or 55 degrees F
- Spraying epoxy paint is highly toxic and requires full protection of a suit and respirator. Not just a simple mask.  If you plan to spray, look into the proper procedures as there are some serious warnings about the health impact
- Brushing epoxy paint is less toxic and possibly safe to do without special equipment. Iíd love to get more information on this and will prior to painting anything.
- Some products are easier to apply via roller/brush than others.  Anecdotally, Interlux Perfection is easier to brush than Awlgrip.  I have no facts to substantiate this other the claims made by posters on the Internet.
- People suggest between 1 and 4 coats with most saying 2-3 coats is sufficient.  Some of the products suggest a thickness per coating to obtain the UV and other protection.  So you would coat as many times as required to reach that thickness

Preparation steps tends to have less debate.  The general consensus is to remove the existing coating and/or rough up the existing coating prior to painting or coating.  The steps are:
- Remove/rough up existing coating without damaging the carbon fiber.
- 320 grit sandpaper is recommended the most, but you can go higher and lower based on your situation
- A flexible razor is recommended if the coating is flaking off
- Do not sand or scrape away the carbon
- Clean it thoroughly.  Recommendations range from water to water and soap to degreaser
- Remove any remaining dust
- Unless youíre painting a brand new mast, it does not seem that any primer is required.
- Interluxís guidance for putting Perfection Plus clear coat over an existing mast was simply: sand, clean, and apply the clear coat

Having compiled the above list of conjecture, Iím still faced with the challenge of what to do:

Cover or leave exposed?  It seems like a clear coat is the minimum and a ďmarine gradeĒ one with UV blockers.

Clear coat or paint?  Arguments for paint seem logical and there isnít a significant cost differential.  The deck mounted sprit and itís cover could benefit from painting so a white paint may save money because I would only need to buy one paint.  Also, if the anecdotal evidence is true, I wonít have to paint again for many years.  That said, Iím not convinced that simply clear coating it would have any negative impacts.

Professional or do-it-yourself?  Cost vs. quality of output as well as safety.  A professional should have appropriate safety equipment, space, and tools to do a better job than I would.

Brush vs. spray?  Based on what Iíve read, it would cost a good amount of money to get the equipment and personal protection to spray it would to buy a few brushes.  If i could afford to pay someone for the work, I would opt for spraying since I would assume that finish would be much smoother.

Color?  Practicality vs. coolness. White would show some of the dings, reflect heat and allow me to paint the sprit as well.  Losing the black color (clear or painted) might make me less cool.  Silver might let me pretend it was aluminum

Brand?  Iíve read in a few places that Interlux Perfection is easier to apply with a brush.  I canít substantiate that, but a few people have made that comment. 

2 part vs. 1 part?  This type of thing isnít fun for me and Iíd rather do it less often which points to using 2 part.

Any rational feedback or guidance would be appreciated.

TimPorter

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Re: Carbon fiber mast maintenance and coating / painting
« Reply #1 on: March 17, 2020, 07:33:20 PM »
Sand all the crap off with 120 then 220.  Spray Duratec Sunshield Clear on it using their thinner.  That stuff will flex with the mast so it won't craze or crack.  100% UV protection.
« Last Edit: March 17, 2020, 07:35:12 PM by TimPorter »

Tac Boston

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Re: Carbon fiber mast maintenance and coating / painting
« Reply #2 on: March 17, 2020, 07:44:29 PM »
Go to the viper class forum, they had the same issue as their masts are c-tech's as well.

PurpleOnion

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Re: Carbon fiber mast maintenance and coating / painting
« Reply #3 on: March 22, 2020, 11:45:00 AM »
Many thanks for the replies.

I ran into this on the Viper site.
https://www.viper640.org/builder/repairs-upgrades/care-of-carbon-masts/