Orange peel surface

Submitted bystitchnz onWed, 04/01/2020 - 16:08

Hello

I just finished building my Shrike Too from CNC. I’m happy with it overall. Definitely a learning experience. If I did it again I would NOT have used fibreglass tape and would have used glass cloth so it would not show the tape. 
I sanded the epoxy down too much I think and thought the imperfections would be taken care of by the enamel paint (it didn’t). I’m considering sanding the hull A bit ( not back to wood) and fairing it with West System 410. Then sanding and repainting. Is this a good idea? Any other suggestions? 
 

Hull

JohnAbercrombie

Thu, 04/02/2020 - 12:28

Pictures  always emphasize every flaw! Does your boat pass the 'Ten foot test" ? :)

Some thoughts: How much time/work/money do you have invested in this boat? One possibility would be to just use it 'as is' and build the next one a bit differently. The deck looks pretty good.

Adding epoxy fairing compound (WEST Microlight) does work well, but it will add weight. And expense. I use Microlight in the fill coat of epoxy on my boats.  On your boat, I'd probably try to strip the paint to get a better surface before sanding and adding fairing compound. Wash the epoxy to get a clean surface before sanding.

Taping only the seams can work, but as you mention, commercial glass tape with woven selvage doesn't lie flat very easily. Using PeelPly helps a lot to flatten the tape edges. Doing a bunch of test joints with scrap will help you get 'a feel' for how little epoxy is needed. Glass tends to 'float' in epoxy.

Thanks for this JohnAbercrombie .  There are SOOO many things I would do different!!

Tthe fact you can see the tape might be that I put too much epoxy on it?  I was LATER told by my supplier that this type of tape never goes clear.  So it might be operator error and/or the product.  I have a little bit of free time since we are in lockdown for 3 more weeks and I bought the 410 before everything closed.  So I could do this. However, I am really trying to keep this kayak as light as possible so I would imagine putting on the fairing would add a bit of weight and possibly make it unbalanced.  Opinions?  

I do have a little PeelPly so I might try that first on the deck since I am hoping to keep that clear and just varnish it.  Even though it has been like this for weeks if I put another layer of epoxy down and then PeelPly could it possibly make the tape vanish?  Could it do the same on the painted section? I have never used Peelply.  Any good website/tutorial on what it can do and how to use it? 

Thanks for this JohnAbercrombie .  There are SOOO many things I would do different!!

The fact you can see the tape might be that I put too much epoxy on it?  I was LATER told by my supplier that this type of tape never goes clear.  So it might be operator error and/or the product.  I have a little bit of free time since we are in lockdown for 3 more weeks and I bought the 410 before everything closed.  So I could do this. However, I am really trying to keep this kayak as light as possible so I would imagine putting on the fairing would add a bit of weight and possibly make it unbalanced.  Opinions?  

I do have a little PeelPly so I might try that first on the deck since I am hoping to keep that clear and just varnish it.  Even though it has been like this for weeks if I put another layer of epoxy down and then PeelPly could it possibly make the tape vanish?  Could it do the same on the painted section? I have never used Peelply.  Any good website/tutorial on what it can do and how to use it? 

JohnAbercrombie

Thu, 04/02/2020 - 23:47

Peel Ply: I've used PeelPly quite a bit, but only when laminating glass or carbon cloth or tape. I don't think there would be any point using peel ply on straight epoxy. PeelPly helps to get excess epoxy out of a layup, and it leaves a good (matt) surface for further laminations. So it's probably something 'for the next boat' .

A search online (Google) will turn up lots of info and videos on using Peel Ply.

About tape wetting out. I have bought quite a few tapes (from China and also from US suppliers) that didn't wet out easily and would never wet out clear. Like most things with epoxy, doing some tests before using a product on the boat is a good idea. 

I didn't do this enough when I was starting building; I was so 'impressed' with the cost of epoxy that I didn't want to 'waste' any with experiments.

Grinding off a few mistakes taught me that it was actually cheaper (and faster) to do some experiments! :)

Another symptom of the 'epoxy is expensive' thinking was my early habit of putting 'leftovers' on the boat. e.g. : "I'll just put a bigger fillet here, or pour the rest of the epoxy into the end of the boat to make it stronger."  Not the way to make a light boat...

JayBabina

Fri, 04/03/2020 - 08:48

We were all beginners at some time. You were gun shy about sanding. You can use your ROS and taper those tape edges and thin out the tape too. You have tape inside the boat and fillets so don't worry about the strength. You can taper those edges right down to nothing. 100 grit. I assume no glass cloth on the wood?  So then you just sand the orange peel with finer grit. 150. Back when I used tape, I learned to warm my epoxy for good saturation. You can use a small scraper to soften the edge on the tape before sanding.

Try this. Try wet sanding the tape on the deck with a fine Wet/dry paper like 200 or so. Try one small area. Very often since its wet, you will see the tape become transparent. Its worth a try. Again, you will taper the tape to nothing and reduce its thickness. I use my pad sander for that fine sanding.  You could start with dry ROS sanding. You just don't want to cut into the plywood veneer.  Good luck.

JohnAbercrombie

Fri, 04/03/2020 - 11:44

Jay is absolutely correct with his advice in my opinion; I agree completely.

Your boat would be strong enough for normal paddling (not deliberately smashing into rocks!) without any tape at all on the outside.

So don't be afraid to sand down that exterior tape - aggressively.

Sometimes when I'm sanding next to an area that I don't want to damage, I put a strip of masking tape on the 'don't touch' area. It reminds me to keep the sander working where I want it to. Remove the tape for final feathering.

Get a stack of good (fairly coarse - I'd probably use 60-80 grit to start) sanding disks and don't be afraid to change them when they get dull of clogged. With good disks, you won't need to put much pressure on your sander. Pushing down on a ROS sander isn't very effective and also wears out the velcro pad more quickly. BTW, the 'Pad Savers'  by Mirka work well and do extend the life of the sander pad. They are available in standard hole patterns to fit any sander.

Thank you all for your wisdom.  Wish I came here when I was building the kayak.  Live and learn!! I have discovered that I am very reactive to the fiberglass dust on my skin (did not wear PPE at first!).  So I am trying to minimize my dry sanding.  I will try the wet sanding first and see what happens.  Thankfully I stocked up on supplies before the lock down here so I have most of what suggested.  Sounds like when I can I will buy a cabinet scraper since I have heard that might help with this also.  It appears you are all suggesting I should not sand a bit and fair with 410 since it will add weight.  Is that correct? Thanks again.  

JohnAbercrombie

Fri, 04/03/2020 - 19:11

I think what Jay suggested, and what I would also suggest, is to sand down the existing tape edges and feather them into the plywood.

So, lots of sanding.

You could probably re-paint over that, or if necessary, use a small amount of 410/epoxy to conceal the tape edges.

If you have a shopvac or other vacuum  and can improvise a vacuum pickup, that would be something worth doing. Fiberglass sanding dust isn't very good to breathe, and it causes skin itching in most of us. Long sleeves with tight wrists are a start.

Wet sanding is mostly for hand sanding - with a typical 110volt ROS it isn't very safe. Also, wet/dry sanding disks aren't a real common item.

So you will have a good pastime for lock down time if you hand-sand all those tapes! :)

 

JayBabina

Sat, 04/04/2020 - 07:51

Everyone is allergic to dust. I assume you are in the US. Do your sanding outside. Once a boat is in one piece, a lot of my work went on in the garage or outside. So much easier to deal with. I do have a shop space but not a super high-tech dust collection etc. Boat building just requires a lot of sanding.

Another option is use use a carbide scraper to feather the edges of the tape. It has the advantages of not creating fine dust and it doesn't scrub particles into the surface, that could make it less clear. Look for one with a double-sided blade that's curve on one side and straight on the other. The curved edge works best when feathering edges into a flat surface, like the sides of your boat. Angle the scraper slightly and it will peel off nice, smooth curls of epoxy and glass.

BTW, the scraper I use is a 2" model from Sandvik (now called Bahco). Regardless of the brand, make sure you get a carbide scraper, as fiberglass will dull a steel scraper in a heartbeat.

One additional advantage of a scraper is that it can be used on Kevlar, which you can't sand because it will get fuzzy.

Don't use a spokeshave, you'll ruin the blade. A steel scraper will work for wood, paint and epoxy, but it won't work well on fiberglass, unless you've got nothing better to do that to sharpen it after every few strokes. They're definitely handy, so by all means make one if you like.

Carbide is harder than glass and can only be sharpened using diamond abrasives. I've done a fair amount of fiberglass repairs with my scraper and I've never needed to sharpen it. You can buy one online and have it delivered, can't you? Surely there must be woodworking, paint or boat building suppliers in NZ that sell them.