12 replies to this topic

[RMK]

I picked up a used boat and the mast, boom, etc look like they need to be re-coated as they look a bit sun burned. Not a big fan of that itchy feeling. I'd rather not paint but is uv (spar) varnish the way to go? I'm thinking I will need to sand off the damaged clear coat but do I need to epoxy before I varnish it? Any help would be much appreciated. Thanks in advance.

[WCB]

I used this stuff: http://www.jamestown...ethane Topcoat and a Preval sprayer to clearcoat my A Cat mast a few years ago. It worked great, was easy to use, quick to dry. Love the stuff. I just lightly sanded the whole mast, cleaned it well and sprayed this stuff on.

[walterbshaffer]

I picked up a used boat and the mast, boom, etc look like they need to be re-coated as they look a bit sun burned. Not a big fan of that itchy feeling. I'd rather not paint but is uv (spar) varnish the way to go? I'm thinking I will need to sand off the damaged clear coat but do I need to epoxy before I varnish it? Any help would be much appreciated. Thanks in advance.

No. You want a clear coat.

Do a search on these forums as this question has been asked and answered in good detail before; you'll learn all you need!

[couchsurfer]

I used this stuff: http://www.jamestown...ethane Topcoat and a Preval sprayer to clearcoat my A Cat mast a few years ago. It worked great, was easy to use, quick to dry. Love the stuff. I just lightly sanded the whole mast, cleaned it well and sprayed this stuff on.

.......+1,,,,you'll get a lot more durability from a 2part clearcoat than varnish,,
,,though I'd recommend you blow-off the surface with a compressor,,and wipe with solvent for 'cleaning it well',,,go ahead and brush-on if you're lowtech,,or don't want the fumes/overspray

...don't forget to ventilate

[Gouvernail]

In my part of teh world we have a yellow ball that glides across the sky every day. That ball emits large amounts of radiation which heats up black carbon structureds to a "too hot to touch" temperature.



When those structures are struck by liquid H2O ther is s suddden and dramatic cooling of those structures.



There is no epoxy that expands and contracts at the exact same percentage as carbon fiber and as such, every single heating and cooling cycle works to break teh epoxy loose from teh carbon fibers.


Further...warm epoxy is typically much less stiff than cooler epoxy.



This means the very hot black epoxy and carbon structures tend to flex more then those which are cool. Flexiong leads to various stresses which eventually result in weakening and breakage.



Whenever possible, I paint any black epoxy carbon structure with a,light colored urethane topcoat.

[couchsurfer]

..good point gouv,,,that yellow disc isn't such a problem here.,kinda wish it were
...though I'm a tad surprised that....
''Further...warm epoxy is typically much less stiff than cooler epoxy.
This means the very hot black epoxy and carbon structures tend to flex more then those which are cool. Flexiong leads to various stresses which eventually result in weakening and breakage.''

...I would have thought that heat-curing during manufacturing would have taken care of that,no??

[El Crapitano]

Epoxy has a value Tg, the glass transition temperature, where it becomes highly plastic. As it approaches Tg it gets soft as Gouvernail says. There is no heat treatment that can prevent this. Some epoxies have a higher Tg than others. Keep your epoxy cool. If I remember right 168 F may be the Tg of the last epoxy I used.

[RMK]

Thanks for all the info. The System 3 stuff sounds great w/water clean up/thinning. Probably will try to spray.

[Great Red Shark]

can second the use fo the System 3 primer and paint - good stuff.

[Gouvernail]

..good point gouv,,,that yellow disc isn't such a problem here.,kinda wish it were
...though I'm a tad surprised that....
''Further...warm epoxy is typically much less stiff than cooler epoxy.
This means the very hot black epoxy and carbon structures tend to flex more then those which are cool. Flexiong leads to various stresses which eventually result in weakening and breakage.''

...I would have thought that heat-curing during manufacturing would have taken care of that,no??

Dunno... MY science runs out somewhere.


I do know we regularly heat epoxy stuff with a heat lamp when we need to crack it out in little pieces...like when we glue a new flex joint in the end of a tiller extension.







Perhaps I am sssuming the same happens to epoxies all the time and don't know shit about what I am saying...



That happens a lot.. But I do try to err on the conservative "it might break" side whenever i don't know shit.

[RMK]

Ok, I used the system 3 clear coat recommended above by WCB. Thanks! Thins and cleans up with water. It was pretty easy to work with despite our record heat. This is the before picture.

Attached Files

•  1169 bow tube.JPG   114.83K   47 downloads

[RMK]

This is the result. I brushed it on with a foam brush. Turned ok despite me.

I wasn't planning on doing the pole but had to remove it to get to two screws. Got that itchy feeling so did the pole too. Also did the racks, tiller and boom. No more itchy feeling which was the primary goal.

Attached Files

•  bow and pole a.jpg   523.02K   84 downloads

[WCB]

This is the result. I brushed it on with a foam brush. Turned ok despite me.

I wasn't planning on doing the pole but had to remove it to get to two screws. Got that itchy feeling so did the pole too. Also did the racks, tiller and boom. No more itchy feeling which was the primary goal.

Nice work RMK! What a difference...