Thread: Can Interlux Brightside be mixed with epoxy

No you can't mix a single part (or two part for that matter) polyurethane paint with epoxy. Adding small quantities of paint to epoxy will tint it, though you have to be fairly careful, because it does affect to the ability for epoxy to "grab" a surface.

A two part polyurethane is orders of magnitude harder then the single parts, but it needs to go over a solid base (primer). This will not help much if you bang the keel on the trailer or run aground, but is better then regular paints.

Consider attaching a sacrificial strip of bronze, stainless steel, HDPE or other plastic or the traditional strip of hardwood. This "keel shoe" will save you boat's butt and can be removed, banged straight or replaced when necessary.

Another option is the epoxy/graphite coating. A number of timber yak builders say this gives a more slippery hull with a very hard, abrasion resistant finish. Personally I think it would have little or no effect on performance but would help when being loaded/unloaded, dragged up on a beach or over logs etc. I have done it to mine recently and it does seem harder than plain epoxy.

If you decide to go this way you will need to sand off the PU from the bottom of the hull so the epoxy/graphite will stay on. Most people say 3 coats will do it but I have only used 2 at this stage. Will probably add 1 or 2 more next winter.

I guess it's a personal thing but I would rather sand the bottom and roll on 2 coats of epoxy/graphite than attach (and periodically replace) strips of brass or hardwood.

Also, Hairymick swears by the graphite - and he has a lot more experience than I do.

Good luck with it whichever way you go.

Howdy,

I have dug in pretty hard with the graphite epoxy question. It has long been used to do a fake black line between teak veneers on decks and line centreboard cases to lubricate the centreboard.

It is quite easy to sand - nothing special - so the claims about hardness around the net are wrong.

There is some suggestion that it helps boats slide off things undamaged. But if they get one so wrong, maybe the other claim is wrong too.

It also depends what they are using as paint. A lot of folks in the USA use water based house paints or latex paints for cheapness etc. I would suspect it is way softer than the quality marine enamels we tend to use - it does peel off the ply way easier. So if the epoxy/graphite is being compared to these it will come up a clear winner.

I don't think anyone has actually done some testing. Would love to see some if it has.

The point I guess is that any boat is going to get scratched. With good quality materials it will take longer to get significant scratches than using cheap materials. When the boat gets scratched .... it it exposes bare wood you should get some epoxy and paint on it in the next couple of weeks. But if it is not right through then don't worry too much.

I guess that's the point Andrew. You are using good quality materials that many of us use as well and we have no significant problems with them. I imagine you have some glass tape or glass along the keel - that will stop almost anything from getting through to the wood.

So don't worry and get right into enjoying the boat!!!!

Best wishes

MIK

Mik,

I tend to agree with you. I resisted the graphite coating for several months because the hardness and drag claims do not make sense. Graphite is a good lubricant because of it's layer structure and the fact that it is soft. Adding it to epoxy is not going to harden the mixture.

Having said that it does seem to be more ding resistant than straight epoxy. My theory is that adding the graphite bulks up the epoxy so you get a thick layer that takes longer to wear through - sort of like a very wide sacrificial rubbing strip. The graphite also protects the epoxy from UV degradation so it can be sanded smooth and reapplied without taking it all off.

Being an ex materials laboratory rat I too would be interested in seeing results of testing under controlled conditions. Would do it myself if I didn't spend so much time in front of this idiot machine .....

Quite right ... that is another claim ... the lower drag.

However what works between two surfaces doesn't work with water because the water doesn't slide over the surface at all but goes along for the ride (boundary layer). So it doesn't matter how slippery the surface feels to a hand.

Best wishes
MIK

I think the graphite stuff also comes off on your hands and anything else that rubs the hull as well doesn't it?

On bigger boats that sit in the water all the time it works as an antifoul coating as the barnicle spores can't attach themselves, but I agree, on smaller boats it's a waste of time...

Graphite will dramatically improve the compressive qualities of the cured matrix, but also increases the brittleness too. The slippery aspect is questionable as you are still rubbing against resin too. I suspect the racers get more from wet sanding with 3500 grit then their graphite bottoms.


There are better choices for slippery surfaces or improving compressive qualities.

Impact damage on surface coatings is extremely difficult to protect against. Most of us just live with the fact that we're going to get dings and repair them promptly.

Abrasion resistance is a different matter and you have choices. Xynole and Dynel sheathing would be the first line of defense, followed with a few layers of regular cloth as a second choice. This is for the "stick it on" solution, which to me seems self defeating. I'd prefer to opt for a sacrificial shoe. The logic being, I know I'm going to ding it up, so why bother making it pretty, fairing it in and painting, when all I need to do is unscrew and replace it when the time comes. In the shoe route I'd use HDPE first as it's inert, but then there are solid back half oval strips of stainless or bronze too. These are more traditional and work well. Wooden shoes are an inexpensive answer as well.

Thx for the responses, but I'd like to understand something more about the chemical bit of it all.

My understanding is that acetone is a solvent for epoxy, and that "enamel thinners" is the preferred solvent for Interlux Brightside PU paint, the latter being very similar to acetone (perhaps I am wrong here).

Given that the solvents appear to be very similar, why doesn't the solvent then "carry" both the PU paint and the epoxy in a way that they would meld if they were mixed and painted onto a surface together, when the solvent evaporates?

I understand that epoxy doesn't coat well over paint, as it seems to interlock with the grain of wood, but I'm actually trying to repaint a fiberglass kayak, and just want additional abrasion resistance along the keel, as I tend to drag it across the beach to launch it.

Yes, I could carry it...........
Yes, I know it's not a wooden boat, and shouldn't be in the forum, but I have just made a wooden dinghy, and my questions extend from this.
No, I don't want to coat it with graphite and epoxy, as I'd like my kayak to be yellow.

Any useful input would be appreciated.

AA

The two products are not meant to work together. I am surprised that you think they would (I am not being mean .... just being surprised).

Does adding cheese to epoxy make it more edible?

But to go into the one explanation I can see ....

First epoxy doesn't cure by evaporation, it cures by chemical reaction. If you add thinner to it, the thinner will reduce the physical properties of both strength and waterproofness.

But main reason is just adding complex things together almost certainly won't have a useful effect.

The solvents are not the same either.

Best wishes
Michael

Originally Posted by Boatmik

Does adding cheese to epoxy make it more edible?

Michael

Ummm, probably Maybe adding epoxy to cheese makes cheese a better glue too?

This thread is really starting to provide food for thought, or should that be food for glue, or glue for food?

Sorry MIK, I couldn't help myself. Must be the extra glass of Hunter Valley RED kicking in....

Thanks. I love cheese.......... but wouldn't eat epoxy.

I was under the misinterpretation that once you mixed epoxy, it was the evaporation of the solvent that assisted the "melding", and by a similar process, if you mixed two things that had the same solvent, once the solvent evaporated, the residuum might bond together (perhaps by some miracle.....).

Obviously there is more to it than that, but I suppose the basic concept I had was that if you mixed the agents together, diluted the reaction with a solvent, added a colouring agent which was also soluble in that solvent, and then let the solvent evaporate, then the residuum might be that the epoxy incorporates the colouring agent, and retains its strength. ???Apparently not true

And, for what it's worth I have fiberglass kayak, but having just built a wooden boat, I figured, I could ask such questions on this forum.

AA

Woodeneye, please just enjoy the red...........

I like soft cheese best, but epoxy just doesn't add to it .
.
As I've also had a few reds, I can't even remember the name of the cheese I love best.....................now I've got it..................yes, it is "munster", an absolutely amazingly smelly "rotten socks" type yellow cheese, which is almost as good as a hot brazilianed blond who's as horny as you could imagine. Try it.

BUT, have you any input into the PU paint/ epoxy discussion....................??

Enjoy the cheese.....................or the blond......................but I need info about paint and epoxy. I am lucky enough to have both the blond and the cheese.........

AA

One of the problems with solvents in epoxy is that the epoxy sets by chemical reaction and the solvent evaporates leaving worm holes in the epoxy. Strangely enough, and reverting to the cheese analogy again, Swiss Cheesed epoxy is considered not to be as waterproofed or as strong as regular full Cheddar Cheesed epoxy

Richard
I'll have a glass of that Hunter Valley Red thanks

Originally Posted by andrew allan

Enjoy the cheese.....................or the blond......................but I need info about paint and epoxy. I am lucky enough to have both the blond and the cheese.........

AA

Mumble grump. Not talking to you then. No decent cheese left in the fridge at all.
Only the blonde.

Sadly too, there is only Hunter Valley red left in the cupboard.
Will have to rectify that on Saturday amidst Adelaide's glorious Southern Vales.


Back to the original question...

1-pack paints cure by the evaporation of solvent/s.

2-pack paints & epoxy cure by chemical reaction of 2 pure components. If they are
good quality, they should not contain any solvents whatsoever.

Risk of mixing the two different materials:
1. that the solvent/s in the paint are likely to prevent the chemical reaction of the 2-pack from occurring.
2. the chemical/s of the 2-pack components may mix with the paint solvent/s preventing them from flashing off.
3. both.... etc

Either way, the consequence is instead of a harder mix, you end up with a goo that will never go 'off'.

Ever.

And will require you to remove both it and any wood or other surface that it has contaminated before you can attempt -any- sort of re-coat.

Ever.

That's the best scenario, because a half-cured goo is possibly even harder to remove. eg silastic.

Soooo.... How lucky do you feel ....

cheers
AJ