Anyone know if the quality of epoxy resin is dependent on the ratio it is mixed with hardener?
Seeing some 4:1,2:1 and 1:1 out there?
Thanks
Seeing some 4:1,2:1 and 1:1 out there?
Thanks
Epoxy Resin Quality
- Thread starter CYQK
- Start date
These concentrations are important. The closer your mix ratios the better. Follow the directions. Typically the resin is the same for anything you do. It is the hardeners that are different. These hardeners produce fast, medium, and slow cures. West Epoxy Systems has a fourth harder that produces a nearly water clear result - excellent for preliminary coats under varnish and (for what it is worth) a better, longer lasting result than Honey Teak or Bristol Finish - and at less total cost incidentally.
In summary, each of the 3 or 4 hardeners has its own unique ratio.
Charles
In summary, each of the 3 or 4 hardeners has its own unique ratio.
Charles
When a fiberglass layup is made, layers are added before the previous is fully cured. This provides a chemical bond. When repairs are made to fully cured laminate it isn't possible to get a chemical bond. Epoxy is stronger and much better at making this secondary bond. West System has some good information on the Internet.
Epoxy ratios are extremely important. Many epoxy manufactures make pumps to be put in their epoxy containers so that one pump from the resin and one pump from the hardner mixes the exact ratio required. Don't deviate. With polyester resins you can guess more and still have good results, but not with epoxy.
ratio is not dependent on quality of the brand.... the ratio mix from one brand to another makes little difference...
but quality is dependent on ratio, so it is important to mix it according to directions for that particular brand and hardener.
for any given brand such as these two good ones, West Systems or TAP Plastics Marine grade, the mix ratio will change depending on which hardener you are using.... west systems is a thick resin similar to room temperature honey, and tap plastics viscosity is more like warmed honey.... they are both very low amine epoxies. I use both brands, but I like using the tap plastics marine grade the best because it wets out quicker, and easier to put on in a thinner application, with either a brush or a squegee.... and it can be thickened if needed.... thinning any epoxy weakens it considerably, so in my opinion, its better to start out with a brand thats formulated to be thin... but they both are good resins, and its what you prefer to work with...
all things being equal, epoxy is much stronger than polyester for almost every application its suited for....
but quality is dependent on ratio, so it is important to mix it according to directions for that particular brand and hardener.
for any given brand such as these two good ones, West Systems or TAP Plastics Marine grade, the mix ratio will change depending on which hardener you are using.... west systems is a thick resin similar to room temperature honey, and tap plastics viscosity is more like warmed honey.... they are both very low amine epoxies. I use both brands, but I like using the tap plastics marine grade the best because it wets out quicker, and easier to put on in a thinner application, with either a brush or a squegee.... and it can be thickened if needed.... thinning any epoxy weakens it considerably, so in my opinion, its better to start out with a brand thats formulated to be thin... but they both are good resins, and its what you prefer to work with...
all things being equal, epoxy is much stronger than polyester for almost every application its suited for....
Epoxy has different properties than polyester resins, but polyester is just fine for certain types of repairs. People think epoxy is the only way to go. But, I don't agree having repaired boats for many decades. No sense spending the increased cost of epoxy to do the job that a polyester resin can accomplish. So, pick your jobs for each.
I agree strongly with Bill.... and cured epoxy will not stand as much heat as cured polyester will.
Not necessarily. In fact it could be said that a 1:1 or 2:1 is better because small variations in mix quantities don't produce much of a ratio change. There are other factors in the formulations that have much more to do with "quality". As others have already stated here, some formulations may wet out better, but may lack in other characteristics. Practical Sailor did a test a couple of years ago on 5 or 6 popular brands. As I recall, West System came out on top over all. The tests measured wet out, shear strength, peel strength, amine blush, and perhaps others I've forgotten. The mix ratios of the brands varied from 2:1 to 5:1.
I think what others are saying here is that the "quality" of epoxy is not dependent on the ratio of hardener to resin. Not all epoxy is the same. One company's formulation may be better in a given application than another. Some aspects of the formulation may have use characteristics that make it easier or more difficult to deal with, or more consistent than another. These factors are completely independent of mix ratio. I have used West System at 2:1, Raka at 2:1, and Marine Tex at 5:1. Personally, I find Marine Tex to be a PITA because it's difficult to estimate a 5:1 mix ratio in a putty form. Why can't it be like other, non-marine products that use a 1:1 ratio? Not being a chemist, I couldn't say. Still, my Grandfather and I have had mostly positive, consistent results from Marine Tex.
I know kayak builders who use West Systems. Come to think of it, I've used old MAS epoxy where the hardener had turned a brownish color, and it still hardened and built the kayak. Others use Silver Tip. Many feel that West Systems has great consistency, and works all the time. This Raka stuff I have been using for wood powder thickened gluing and sealing wood has been doing fine for 5 years now. I initially bought 3 gallons, 2 resin, 1 hardener, to use to coat and seal a wood boat restoration, and I've been using it for all sorts of other projects because I haven't been restoring that boat. Just this past weekend, I used it to repair a hole in my Force 5. I put in a new piece of fiberglass into the cockpit of a friend's boat the weekend before that. I got it at the recommendation of other kayak builders, because it was half the price of West System. It comes out hard in the end!
One thing to be aware of, people have gone looking for ways to make the ratio mix easier. I know people who thought they hit the jackpot when they bought a gram scale and started measuring percentages by weight, only to run into trouble because the manufacturer specifies ratio BY VOLUME. So, yes, read your manufacturer's instructions carefully, and call them directly if you have any questions.
As for polyester vs. epoxy, know that people have been repairing cured fiberglass with properly crafted polyester resin patches for as long as there has been fiberglass laminates. On the flip side, from what I understand, epoxy was created as an adhesive, and sticks to darn near anything. I have also read that epoxy makes a chemical bond to cellulose, so it is an ideal material for working with wood. Polyester is not nearly as good at adhering to wood, or other things...
Most of the sellers of epoxy resins are "blenders" of the resins they buy from places like DuPont. They do not manufacture and most epoxys probably come from the same few suppliers. The harderner
there is a lot of good information here... but the need to measure by volume in not ALWAYS the case.... some resins and hardeners can be very accurately measured by weight.... but again, like has been said several times already, follow the manufactures recommendations
Sorry! The hardeners used will become part of and change the chemistry which will change the properties when mixed into the given epoxy resin. The different hardeners are often mixed with different ratios. Changing the ratios for a given hardener will only screw it up. Polyester or vinylester use a cat. to speed the gell to cure. The cat. can be changed to a small degree (1 to 3%) to slightly change gell times. Polyester also comes in many different types but the cat. will not become part of the chemestry, . Buy only from those that know the difference!!
As to what is a better epoxy hardener-- what are you using it for? Again, Buy from those that know what they are selling.
As to which is better? A quick answer is that many epoxy systems will have a higher adhesive value than poly. but the vinylester is very close. The question is how much do you need? My answer is that I will usually do a test patch before using. (many boat manufactures will use addatives in their resins to speed the cure) Most of the 3 basic resins will tear away a few layers of glass and not release at the surface. Why would you use epoxy that will cost about 3 to 5 times poly. ? There might be but not often.
As to what is a better epoxy hardener-- what are you using it for? Again, Buy from those that know what they are selling.
As to which is better? A quick answer is that many epoxy systems will have a higher adhesive value than poly. but the vinylester is very close. The question is how much do you need? My answer is that I will usually do a test patch before using. (many boat manufactures will use addatives in their resins to speed the cure) Most of the 3 basic resins will tear away a few layers of glass and not release at the surface. Why would you use epoxy that will cost about 3 to 5 times poly. ? There might be but not often.
Because epoxy is waterproof and and elastic, important properties in boat building.
Epoxy is NOT waterproof. It sometimes is more flexable than poly but only if properly mixed then cured which most often be needs to be done in an oven. Even then the reinforcements will break or delaminate before most resins will fail.
Epoxy is NOT water proof. Where have you found any study of how effective a barrier coat is or even what causes a blister . At least one boat manufacture will void its warr. if their gellcoat is sanded to put on a barrier coat. I would agree that epoxy is a product that has its place but is far and away overused. Too much armchair boating.