Thanks, Lee
Thanks for the tip on the Tru-Value. Who’d a thought?
Where do you get your Rakka?
I think I will carefully monitor my hardener/resin supply so they exhaust together, then switch to Rakka the next time I need epoxy.
I wonder if CLC web prices are up to date. I asked about the priciness and was told, it’s all based on oil and oil has gone up.
~~Chip
switching epoxies
Back to the original poster, pumps and fillers are not epoy specific so that should not make any difference in future decisions. If you have a bunch of left over hardener, I would stay with the same brand.
BTW, the epoxy odor “in the day” came largely from the highly volatile MEK (methyl ethyl ketone") that was used as hardener. You only used ounces of MEK to gallons of resin, which is s good thing cause that stuff was nasty.
recent Mas experience
A friend gave me about 2 ounces of Mas epoxy. I really spreads well. The little bit wat enough to put a fine coat all over the bottom of my stripper to hide the scratches.
I think the Mas is thinner than some varnishes I have used.
MEK is not a hardner for Epoxy
Chemically impossible ! It is a solvent from the same family as acetone.
MEK hardener
Correct. The actual hardenr is methyl ethyl ketone peroxide, but in the boatbuiding industry it was shortened to MEK.
OK
But as a paint technologist I know MEK as a solvent.
Pumps & Mix Ratios
The mix ratio, of resin and hardener, varies among epoxy systems. West is 5/1, I think MAS is 2/1, and I was looking at another brand that is 5/2. The West pumps provide the correct ratio with one pump from resin, and one pump from hardener.
As I am figuring this out, I see I could use the pumps for different ratios. Two pumps of hardner to one resin would give me the 5/2. Two resin and five hardner for the 2/1.
~~Chip
Blush free- Don’t believe everything
– Last Updated: Oct-19-07 10:23 PM EST –
they advertise. I've used both MAS and System 3's Silvertip resin's with slow hardener and have experienced small areas of blush with both. I've seen commentary on the Kayak Building Bulletin Board where others have made the same discovery.
There seems to be a correlation between temperature and high humidity which causes the blush to form in these "no blush" hardeners.
My SOP (standard operation procedure) now is to wash cured epoxy with water mixed with a little bit of ammonia, then lightly sand before applying more epoxy or varnishing. I do this even if the hardener is advertised as "no blush". Let the buyer beware!! : )
Tripp (two strippers complete and soon to begin on 2 1/2 more)
Pumps are not always reliable…
Air can get in and you won’t get a full pump and throw the ratios off a bit. Also one pump of each may give you more epoxy than you need and lead to waste or a really heavy boat.
Foolproof is keeping two separate measuring cups, measure resin and hardener separately then mix it in a third.
I found that out the hard way
Inexperienced with epoxies I was blissfully relying on the west system pumps for proper ratio mix and when it wasn’t curing the way it was supposed to I measured the pump output with a measuring cup and found them off quite a bit. For awhile I thought it would end up costing me a lot of extra labor but in the end it did set up OK.
Moral of the story—don’t trust those pumps–they’re convenient dispensers but use a measuring cup for proper ratios.
Bob
It’s still not a hardener for epoxy
MEKP is a hardener for polyester resin. It’s purely a catalyst that accelerates the curing process. Polyester resin will eventually cure regardless of whether hardener is added, which is why it has a finite shelf life. MEKP is a “universal” catalyst for polyester resin and the brand makes no difference, since it’s all the same chemical.
Epoxy hardener is a integral component to the resulting cured plastic, not just a catalyst. Epoxy resin cannot cure without the appropriate hardener and the chemical formula for both resin and hardener vary from product to product. The mix ratio can also vary from 1:1 to as much as 10:1, though boat building products typically have mix ratios of 5:1 or less. You cannot use one brand of resin with another brand of hardener.
Measuring
I totally agree with not trusting the pumps. I’ve never used them, but have heard plenty of stories of epoxy ratio blunders.
What I do is use the disposable 10oz. Solo cups for measuring and mixing. To mark off the graduations, I put one cup inside the other and then start adding water to the inside one. I put 1 oz. in and mark the level (on the outside cup) with a fine point permanent marker, put another oz. in and mark off that level, and so forth. I also mark 1/2oz. levels up to the 4oz. mark (I think). With this system you don’t have to measure the resin/hardener in separate measuring cups. You just pour in a certain amount of resin, then add hardener to the right level, and mix. If I want 6oz. of epoxy, I put a fresh cup into my measuring cup, add resin to the 4oz. mark, then add hardener to the 6oz. mark (2:1 ratio) and stir. No need to transfer to a third cup for mixing, more accurate since you don’t lose any material stuck to the inside of your measuring cups, and your measuring cup is always clean.
Pedro Almeida
Mixing small amounts…
They are getting hard to find but I use the translucent 35mm film canisters. It makes 2:1 easy to just eyeball. I would go in and ask for used ones whenever I saw a photo mini lab.
Re: mixing small amounts
And if you use 3 to 1 or 5 to 1 (West system) these little disposable calibrated cups (see below link) are great and can be found locally by calling around to a few pharmacies in your area. I think you can get them in a quantity of 100 for 6 or 7 bucks.
http://www.onlinemedicalsupply.com/AIDS_TO_DAILY_LIVING/MEDICATION_HELPERS/PPI02301/product.aspx
10cc syringes
Last s&g kayak I made was without pumps, I’d rather use 2oz, 6oz cups and 10cc syringes for measuring small quantities.
Syringes
Syringes are very convenient and accurate, just make sure your syringes don’t have that lubricant on the plunger. Most syringes made for medical use are lubricated; I think the lubricant is silicone based. I started out using large syringes to measure the resin/hardener and ended up with contaminated epoxy which resulted in fisheyes. Getting a final, smooth fill coat was a PITA. When I figured out where the contamination was coming from, I stopped using syringes for measuring, and that took care of the problem.
Pedro Almeida
good point
I wonder what solvent would remove it?
I used syringes for small quantities for parts glueing. MAS says fisheyes can also be caused by static charge on the coated surface. Silicone and greasy fingers will definately bring out fisheyes but I’ve had fisheyes in perfect conditions doing all the things necessary to prevent them and no fisheyes on a deck that was just wiped down in a dusty shop.