Epoxy and Hand Lay up Questions?

[XstreamVking]

Itchy and scratchy meet the old crusty, grumpy fiber glasser comics? Those are classics....

[One Oldman]

To get back on the subject of epoxy! Has anyone played with the mixing ratios of hardener and resin. I accidentally mixed a batch with considerable more than recommended hardener. It went to smoking and had about a 5 min cup life. It seemed to cure out OK, so I wonder if small adjustments of more or less hardener could give you more control and still have a good resin. Just wondering. I already know this is not recommended by the manufactures. Just wondering if it would work.

[XstreamVking]

Have mixed it with less hardener for a softer caulk type material to fill between planks of wood on yachts. Mixing more hardener would not work well imo....Would make the resin brittle.

Edit... This was many yrs ago, took a while to remember this... A resin mfg recommended this mix for our project. So this was one particular resin formulation, apparently was designed for variable ratio's. Do not vary the hardener on reg epoxy!

[One Oldman]

I take it that you did get a full cure eventually?

[XstreamVking]

No. Stayed rubbery. It was used a a seam filler between planks of teak wood that would get wet and swell, dry and shrink. So it did work very well for that application.

[dwilfong]

It will work but that said. The cure time determines the strength of the finished product. Medium cure has the best strength.

[tunnels]

To get back on the subject of epoxy! Has anyone played with the mixing ratios of hardener and resin. I accidentally mixed a batch with considerable more than recommended hardener. It went to smoking and had about a 5 min cup life. It seemed to cure out OK, so I wonder if small adjustments of more or less hardener could give you more control and still have a good resin. Just wondering. I already know this is not recommended by the manufactures. Just wondering if it would work.

NOT A GOOD IDEA !!epoxy is very unforgiving when it comes to mixing ratios , that is why you can buy different hardeners for the different uses, fast, medium, slow ,and really slow .
I ask the question how do you dispense and MEASURE OUT your resin and hardener ?? pump ? pour and guess? weigh with digital scales ? what ?? also need to mix the resin and hardener BEFORE you start adding things to make glues or filler etc !!

EPOXY IS NOTHING LIKE POLY OR VINYLESTER where you still have lower and upper limits but there's good choice you can work with between !!
All manufactures have made there products to be used within a specified range and have done countless hours of IDIOT safety testing over many years . The moment YOU step over the lines they have drawn THEN YOU are an------T.
You have no comeback or claims if the product fails in any way ! So to remain within the specs of what you are using USE YOU HEAD and what inside it !!

[powerabout]

have to agree mix ratio's in epoxy are much more critical then esters, most say weigh only and not to mix by volume

[tunnels]

have to agree mix ratio's in epoxy are much more critical then esters, most say weigh only and not to mix by volume

Think simplicity always to almost never have problems !
From the manufacture I ALWAYS GET THE APPROPRIATE DISPENSING PUMPS !!, one FOR THE RESIN AND one for THE HARDENER THEY SIMPLY SCEW ON TO EACH CONTAINER !! Or if you working and using lots of epoxy ON REALLY BIG JOBS a single lever with 2 pumps connected that way NO THINKING INVOLVED just pump and stir and mix and apply !

Working with any resins simple is best !! In the big company where we built the 147 foot boat I had a resin saturator gun set up and all and everyone used that no matter how big there jobs were, Fitted a pour nozzle with a internal mixer so 1/4 of a cup or 6 liters didn't matter . No thinking involved and NEVER HAD A FAILURE of any sort for the whole of the 4 years plus I was there !. Once the catalyst ratio was set it never changed no mater how much resin was used during the day , the mixes were all ways predictable to the minute !!
And the first person to use the gun in the morning set the catalyst ratio according to the weather conditions of the day and took a sample and got the gel time for everyone to see and was written in a blackboard ! team work and everyone working together Never had to ask we all took it in turns to set up each day and was done automatically !! How reliable are your staff and do you trust them ??

[One Oldman]

NOT A GOOD IDEA !!epoxy is very unforgiving when it comes to mixing ratios , that is why you can buy different hardeners for the different uses, fast, medium, slow ,and really slow .
I ask the question how do you dispense and MEASURE OUT your resin and hardener ?? pump ? pour and guess? weigh with digital scales ? what ?? also need to mix the resin and hardener BEFORE you start adding things to make glues or filler etc !!

EPOXY IS NOTHING LIKE POLY OR VINYLESTER where you still have lower and upper limits but there's good choice you can work with between !!
All manufactures have made there products to be used within a specified range and have done countless hours of IDIOT safety testing over many years . The moment YOU step over the lines they have drawn THEN YOU are an------T.
You have no comeback or claims if the product fails in any way ! So to remain within the specs of what you are using USE YOU HEAD and what inside it !!

I measure by volume as recommended by the manufacturer and as per the manufacturer exact measurements are not as critical when mixing large quantities as small. What inspired my original question is this, taken from Raka's website. "I want to emphasize the importance of proper mixing. Epoxies strength and desirable properties comefrom the complete mating of the resin and hardener molecules in the correct ratio. Too little hardenerproduces brittleness, and too much hardener makes your epoxy softer with the accompanying loss ofstrength. If you make an error, you're safer to use a little less hardener, than too much. Generallyspeaking you can have a 20% error tolerance on the minus hardener side and 10% on the plus side andstill get an acceptable cure. Regardless, your cure will have less strength than its ultimate potential!" I see no harm in discussing things that are out of the box. How else can we understand how and why. Some things must be done by the book and many other things can be done in different ways with good results. Understanding which are which is wisdom. Some things are like expensive race car parts. They are designed in such a way that can be modified to work. As to product liability in the U.S., individuals have basically no rights when it comes to product liability on things such as this where the user determines suitability of a product and uses.

[tunnels]

I measure by volume as recommended by the manufacturer and as per the manufacturer exact measurements are not as critical when mixing large quantities as small. What inspired my original question is this, taken from Raka's website. "I want to emphasize the importance of proper mixing. Epoxies strength and desirable properties comefrom the complete mating of the resin and hardener molecules in the correct ratio. Too little hardenerproduces brittleness, and too much hardener makes your epoxy softer with the accompanying loss ofstrength. If you make an error, you're safer to use a little less hardener, than too much. Generallyspeaking you can have a 20% error tolerance on the minus hardener side and 10% on the plus side andstill get an acceptable cure. Regardless, your cure will have less strength than its ultimate potential!" I see no harm in discussing things that are out of the box. How else can we understand how and why. Some things must be done by the book and many other things can be done in different ways with good results. Understanding which are which is wisdom. Some things are like expensive race car parts. They are designed in such a way that can be modified to work. As to product liability in the U.S., individuals have basically no rights when it comes to product liability on things such as this where the user determines suitability of a product and uses.

Some of the problem issues with resins and there mixes are long term ! Not this year but maybe next mysteriously things fall apart for no apparent reason .
If you work manufacturing life saving products and make safety equipment then "she'll be right" and "that's near enough" can cost lives and it just might be your own while racing across the water at 100mph plus ! Sorry but near enough is not good enough!! there's black and while and no shades of gray in any direction!

[One Oldman]

Some of the problem issues with resins and there mixes are long term ! Not this year but maybe next mysteriously things fall apart for no apparent reason .
If you work manufacturing life saving products and make safety equipment then "she'll be right" and "that's near enough" can cost lives and it just might be your own while racing across the water at 100mph plus ! Sorry but near enough is not good enough!! there's black and while and no shades of gray in any direction!

Point Well Taken! That being said, if I were building something to market, I would be more cautious as to liability and safety. However, where would we be without all the experiments and inventions which started in someones backyard or garage and in some cases were fatal. The safety improvements to cars, boats, etc. are usually gleaned from failures. My question was if anyone had tried to vary ratios. After reading the posts here and doing more research, IMO it should be done only with very slight variance and then with the understanding that some loss of strength will result. As for me personally, I will stick to recommended ratios.

[XstreamVking]

Found a bunch of tech mumbo jumbo on epoxys. Read some of it and learn something. It is daunting info to say the least, but that is chemistry...haha http://www.nilsmalmgren.com/epoxy-ch...al-properties/

[One Oldman]

A good read even if you are not a chemist.

[dwilfong]

Well you know I read a comic book and it said to use red Dixie cups and shot cups. 2 of one and 1 of the other.

That is 2 to 1 now is it not??????

But then again wily coyote may have just bin pranken me.................