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Old 01-10-2005, 18:02   #16
Kai Nui
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I have tried that method, but even mixing it hot, I can never get it to kick. I have had to remove several paint jobs on galley counters and shower floors that I tried that on (OK, only one of each, but it seemed like several when I was trying to remove it). How hot is the mix you are using?
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Old 01-10-2005, 22:40   #17
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Just plain old room temp. I do presume you mean by "kick" to start curing? Two pot Polyurathanes will cure no problem. But most epoxie Paints won't. Epoxy based paint is different to Epoxy resin. Epoxy resin hardens fast when in quantity. Most Resins have little solvent and those that do, have a special solvent that doesn't stop the polymer chains linking. Epoxy paint is designed to work the otherway. This is so the paint doesn't turn to a boiling smoking hard lump in the can in a few minutes. It must be in a thin film to start working. The special solvents used are to keep the epoxy chains forming. When in a thin film, the solvent evaporates quickly and the chains start to form very quickly. If you pour epoxy paint in a depth of even say an 1/8", it will probably take more than a week to start to harden.
Now if you do ever try the Polyurathane trick again, one tip, do not shake the mix, stir very carefully. You don't want airbubbles traped in the paint mix as they will surface just as the paint is hardening and leave little holes in the surface. When you have mixed, allow to stand for a good 20mins. This does two things. One, it allows any bubbles to rise to the surface and two, all two pot polys have to be allowed to sit for 15-20min. once mixed to allow long chain molecules to form.
Hope that helps.
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Old 04-10-2005, 17:08   #18
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Varnish “Primer” ~ by Don Casey
“Scratch through the top coat of almost any painted surface and you will find an underlying primer coat. Primer prepares the raw surface for the paint. The result is a better finish.
It is useful to think of varnishing as a similar two-step process. With varnish we don’t use the term primer, but we could. Varnishing raw wood always begins with several so-called “build-up” coats, and these perform almost the same function as primer under paint. We want the build-up coats, first and foremost, to get a good grip on the wood. After that, we want them to level out the surface, filling the wood’s pores. We also want the build-up coats to clarify the wood, bringing out the beauty of the grain.
You can use the same varnish for both build-up coats and finish coats, but the pros often use a less expensive varnish for the build-up coats. Only color and clarity matter; flow, gloss, and UV resistance do not become an issue until we get to the top coats. For a foot-deep finish, plan on applying 6 build-up coats followed by 3 or 4 carefully applied finish coats.”

And he gets paid for this drivel ...
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Old 04-10-2005, 17:10   #19
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Varnish “Primer” ~ by Don Casey
“Scratch through the top coat of almost any painted surface and you will find an underlying primer coat. Primer prepares the raw surface for the paint. The result is a better finish.
It is useful to think of varnishing as a similar two-step process. With varnish we don’t use the term primer, but we could. Varnishing raw wood always begins with several so-called “build-up” coats, and these perform almost the same function as primer under paint. We want the build-up coats, first and foremost, to get a good grip on the wood. After that, we want them to level out the surface, filling the wood’s pores. We also want the build-up coats to clarify the wood, bringing out the beauty of the grain.
You can use the same varnish for both build-up coats and finish coats, but the pros often use a less expensive varnish for the build-up coats. Only color and clarity matter; flow, gloss, and UV resistance do not become an issue until we get to the top coats. For a foot-deep finish, plan on applying 6 build-up coats followed by 3 or 4 carefully applied finish coats.”

And he gets paid for this drivel ... This Forum has done better !!!
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Old 04-10-2005, 19:03   #20
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Wheels, yes, I meant 2 part Polyurathane. I do not shake the mix, and bubbles are not a problem. And yes, by kick, I mean cure. (Sorry, I guess we talk funny over here)
The mix I use calls for 3 to 1. I tried that on the galley, at maybe 1/8" thick. No dice. On the shower, I tried 50/50 activater to material, and much thinner, maybe equivilant to 6 or 8 coats brushed. Still no dice. Might be the brand. Hard to say.
Oh, and by hot, I meant how much activator. As for the epoxy paints, I use Valspar VP-50. This stuff goes on thick, seals against moisture (unlike primer), and is hard as nails. Plus, the poly's like to stick to it. Even the single part.
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Old 05-10-2005, 00:59   #21
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Hmmm, most interesting Kai Nui. Must be something in that brand you are using. I use two brands, mainly because of ease of obtaining. International/Epiglass and Altex Devoe. I use the mix ratio of what the instructions suggest. With both Epoxies and Polyurathanes, (as I have stated before) the mix of hardener and paint is criticle. These two go through a molecular bonding to harden and cure. If you have too much of one or the other, the left over of which ever, will remain trapped in the hardening mixture, but will stop the mixture from curing.
It is Polyesters that use a catalyst and the amount of catalyst will determin the speed of hardening. Polyester resins always want to cure anyway and the process is actually happening in the can, just very slowly without the catalyst. The catalyst speeds up this very slow process to a lightening speed.

Gord, interesting that you brought up the Primer part. Actually all paints have a three part application. It is just that some paints can have part two and three in a single application. The three parts are Primer, Undercoat and top coat. A very good "system" is one that uses all three parts in single applications.

The primer does several things. Firstly, it has good adhesion to the substrate, but it's main function is to seal the substrate from contamintation that could come back out into the paint system. So you will often see Primers also called Sealers or primer/sealers. The finished surface is porouse to an extent, to allow the undercoat to adhere.

The undercoat is designed for build up and cover. It tends to be softer, flexible and easy to sand. It takes up a lot of movment of the substrate, allows the painter to achieve a smooth surface for the top coat and has a good covering effect, to stop the underlying colors and shades appearing through the top coat. The most important thing to remember with undercoat, it is porouse rifght the way through. It will allow moisture through to whatever is beneath and if that happens to be steel, it will rust and the rust will come through the paint system.
Neither the Undecoat or Primer/sealer have UV protection, so it can not be left exposed to weather for long at all.

Top coats are designed for three main purposes. Finish, color and protection. Protection would cover aspects like, it is UV proof, water proof and has wear and scratch resistance. Ofcourse how much depends on what the paint is.
All three parts have a made to adhere to one another. You will not possibly three different time aspects in the product instructions. This will be -touch dry time, -min/max recoat time and- full cure time. To understand why, you have to understand a little about paint. First of all, paint is a mixture of pigments and binders all held in suspension by a few other little aditives that help with flow and staying put on the surface, especially if it is verticle or over head and toped off by a good amount of a solvent. The solvent has two main jobs. It stops the binders from coming together and starting the hardening process and it helps you get the paint from the can to the painting surface by brush or what ever application you are using. The solvent must then evaporate away and allow the binders etc to start doing their jobs of coming together. The binders do two different things in their hardening process. First they just plain harden to allow the "touch dry" aspect of the paint. While the paint is in this stage, any additional coats meld into the previouse coats and become one. The solvents are evaporating away from the surface in the uppermost layer. If the minimum recoat time has not been followed, then solvent gets trapped down in the deeper layers and will destroy the paint by deformation.
The other side of the coin is the curing process. Once enough solvent has evaporated, the binders start to cure. Curing means they are chemically bonding together. If the maximum recoat time has been expired, then the subsequent coat will not chemically bond to the already cured binders. The coat will not adhere correctly, so you need to "key" the surface by sanding, so as the coat has something to grab onto.

I'll stop there, but please understand that the above is simplified. As we all know, there are many paints out there, each with their own special formulae and each with their own special way of working.
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Old 05-10-2005, 07:06   #22
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Regarding Don Casey's varnishing tips ....
I've been varnishing just as described above for 15 years, in that time I have never had varnish lift from the surface, peel, crack, chip, discolor or in any way fail. So .... why on Earth would I try and become a chemist, and mix various varnish potions? Why would I sand between every coat, slowing the "build" process? I suppose if I were a man of leisure, I would take the time to play with such things .. but I never seem to have enough time as it is, and even using my techniques, varnishing is a time consuming task.
I bought my first can of Penetrol just to see what it could do. According to the label, it's a wonder product to be used on metals, fiberglass & wood. I have found it to be an excellent base coat for wood .. made an ugly mess on fiberglass and stainless steel ... but an amazing little discovery. On my last boat, the stern rail was anodized aluminum. Years of sun and salt air had turned the anodizing milky and I thought there was no way of repairing it ... Penetrol returned it to a clear shiny surface! I will admit, it didn't last long (3-4 weeks) but what a difference in appearance!

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Old 05-10-2005, 07:14   #23
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A great tool for sanding...

While we're on this thread, I had been having a heck of a time sanding the little corners boats tend to have. I tried jamming a power sander in... no dice... space is too small.

I tried a wheel that fits on the end of a drill... of course, the drill doesn't fit in the area.

I tried a sanding block... close....

I tried using a folded piece of sandpaper. Worked great, but... I no longer have finger prints at the moment.

After all that frustration, I decided to chance it on a Dremel Contour Sander. (I had already bought the normal Dremel thinking it would sand - it doesn't) The Dremel Contour Sander worked PERFECTLY! It's very easy to use, reaches in places you could reach with a toothbrush, and has variable speeds which are nice depending on the type of sanding you are doing.

It's saving me many hours of tedious sanding in corners, plus saving my hands from all that wear and tear. You literally don't need to hand sand with this tool (except to smooth out variations in your power sanding on large surfaces)

I can't say enough about this thing... it really works!
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Old 05-10-2005, 08:55   #24
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Quote:
I tried using a folded piece of sandpaper. Worked great, but... I no longer have finger prints at the moment.
Just a little trick here, wrap your finger tips with masking tape before hand sanding. Your fingers will be fine even after hours of sanding.
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Old 05-10-2005, 12:40   #25
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Black&Decker have a handy little sander that the base is shaped like the base of an Electric iron, (the thing you iron out the wrinkles in your clothes with) and the call it the "mouse". You can get the tip of it into those little corners and edges.
I personaly have never used it, so I can not give a feedback on how well it works. I have seen it in hardware stores often and just thought, what a great idea. Just a pity it's B&D. (doesn't have a good reputation in NZ)

Bob, I guess it just depends on the finish you really want. I am not defending this Don fellow, maybe you get just as good a finish. However, I saw a finish on a largish yacht once that was like a mirror. A stunning blue that was totally blemish free. It looked like it had been sprayed on and then higly polished afterwards. I didn't know at the time how it was applied, but I did know it was way to soon to have been polished and I asked the ole guy what the paint system was and how many coats he had sprayed. I was absolutly jaw droppingly stunned to find out he had applied it all by brush. He was a truely skilled and very gifted craftsman. I think it is sad that in many differing trades, many of the real skill and talent is fast disapearing. Being replaced by machine and techniques that speed up jobs makeing them cost less, which is good for our pockets, but the end result is we seldom see these true craftsman at there work anymore. And the craft and techniques are dying with them, not being past down.
Now, every time I paint, I try to achieve what that fellow shwoed me what was possible. I have never ever come even close to it. In fact, applying paint is just not one of my talents.
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Old 06-10-2005, 18:46   #26
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Alan,
You're 100% right ... the finish on my table is not mirror like, though with 3 more build coats, another sanding and another final finish coat it would be ... so why not do that? Time my friend, time. We are scheduled to set sail on a long voyage one year from now ... and I have much more important things to do than worry about a "mirror like" finish on this table. As is, it's better than most ... and that will have to do. I lament the lack of traditional talents as much as you ... but I have to be practical ... to turn this boat into the most beautiful yacht possible means never leaving the dock ... and we are leaving! Life is always a series of comprimises .. and this is one I must make, I have not scrimped too much ... I still have a beautifull table (and the rest of the teak is coming along nicely) .. it's just not as "perfect as possible".
On my previous boat, I sought for absolute perfection, and I did some fine work, a friend once commented " Bob ... it's just a boat" I figured he just "didn't get it" ... had no idea on the satisfaction of a job well done. It finally dawned on me, that his boat, which looked so-so at very best, had been from Alaska to Fiji to Cuba ... and wound up here in SW Florida ... mine ... which was becoming "perfect" hadn't left the dock!!! ... I learned a good lesson from him .... after all ... it IS just a boat

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Old 06-10-2005, 21:01   #27
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Sean, and Wheels, the Mouse and the Dremel are basicly the same animal. Another trick that works is using those adhesive disk I like so much, and cutting stir sticks to fit the space you need to sand, then stick a piece of adhesive paper to it. Cheap and easy.
Wheels, I see the problem. I misunderstood you. I believe you were refering to polyester. I was refering to polyurethane. I was going for a thick glossy white surface, not clear. You are absolutely right about the polyester. As for mix ratios, with good materials, you can adapt the ratio to accomodate temperature, an drying times. The VP-50 is an epoxy primer/sealer. the simple difference between primer and sealers, is a primer will allow moisture through, while a sealer will not. Also, as I did not see it mentioned, polyester will not stick to epoxy, however, epoxy will stick to cured polyester.
Another important point, relating to modern materials. The new air quality requirements in the US, especially in California, have completely changed the materials that are available, even in the past 10 years. New paint will not necessarily stick to the old paint. Even with a good sealer, the old sanded surface may have trapped gas, that will react with the primer. Then it ALL has to be removed.
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Old 06-10-2005, 23:43   #28
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No Kai Nui, I was definately refering to Polyurathane. Clear or colored, it doesn't matter. Providing the correct mix ratio is adhered to, it will cure. Some manufacturers may have different pot life times. Just read the literature and see what the working pot life is. It won't start curing before that time if it is poured on thick.
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Old 08-10-2005, 12:40   #29
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Wahoo Sails..Your Table Is Beautiful!!

Hey Wahoo Sails,

That is a beautiful table you got there. Nice work.

I keep telling my boatbuilding partner, that, that's the way we should do our wood work. Providing we decide to go that route.

Beautiful table.


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Kevin
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Old 08-10-2005, 17:29   #30
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OK Wheels. Must be the product.
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