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Thinning Epoxy Resin

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Old 08-08-2005, 10:51 AM
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chelapa
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Default Thinning Epoxy Resin

Hi folks. long time i havnt posted. if im getting some pin holes in the lamination, i think a good way to solve it would be thinning out the epoxy a bit. yes or no?
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Old 08-08-2005, 11:13 AM
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Ed Smith
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Default RE: Thinning Epoxy Resin

NO!. Do not thin epoxy resin when laminating. The resin may not cure properly, The part may cure but be rubbery, the physical characteristics of the cured epoxy will be changed, never for the better.

If not painting in the mold with either color or clear it is almost impossible to be completely free of pinholes. To try and prevent them I lay in a first layer of 1-1 1/2oz cloth. The finer weave does help. This first layer has to be really wet with excess resin. My second layer is usually 6oz cloth and will soak up the excess resin with very little needed to be added. After that then do what you do.

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Old 08-08-2005, 11:24 AM
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Default RE: Thinning Epoxy Resin

I'll try that tonite. thanx! =)
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Old 08-09-2005, 06:27 PM
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Default RE: Thinning Epoxy Resin

The best way to get rid of pin holes is to mix epoxy with cabosil making a very thin mixture just enough so it will not run on verticle sides Paint the mold and let it set until hard . Then lay up part will be pin hole free
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Old 08-09-2005, 07:00 PM
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Default RE: Thinning Epoxy Resin

That works, of course, but it's a heavy solution. Using a very light layer of glass works just as well, and provides some structure.
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Old 08-09-2005, 09:01 PM
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Default RE: Thinning Epoxy Resin

Not as heavy as a light layer of cloth and you can still get pin holes even with a two ounce cloth . Try it before you knock it
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Old 08-10-2005, 12:20 AM
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Default RE: Thinning Epoxy Resin

Ok, I see that you disagree with me. That's ok. I've tried a great many things, including what you suggested. I've found that using a layer of 0.6oz glass gives more repeatable results, with less weight gain. And it's adding fibers (strength) instead of just resin.

I like to make my layups pretty dry, as my goal is maximizing strength and stiffness, while minimizing weight. Cosmetics are also important. The layer of light glass works for me. I never said two ounce... I'm talking 0.6oz-1oz. I guess "very light cloth" is a relative term.

-David
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Old 08-10-2005, 06:21 AM
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Default RE: Thinning Epoxy Resin

YOU CAN THIN A GOOD GRADE EPOXY.. NOT WEST ,ITS RUBBER ,AND SOFTENS IN THE SUN,, THEY SELL EPOXY THINNER,GO FIGURE!! ACETONE OR MEK WORKS ALSO.. NEVER SEEN AND SIDE EFFECTS,, USE ZAP FINISHING RESIN FOR SMALL LAY UPS.. WORKS SUPER.. SPRAY RESINE ON YOUR MOLDS,LET IT TACK UP OR DRY.. THEN LAY ON CLOTH.. I LIKE DRY BETTER,CLOTH SLIDES AROUND EASIER..DONE HUNDREDS LIKE THIS ..GO TO VYNALESTER RESIN ,,ITS THE BEST,,RD
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Old 08-10-2005, 11:30 AM
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Default RE: Thinning Epoxy Resin

Raptor I have been thinking about trying vinylester resin tell us more about it .
s it compatible with epoxy molds ? Also what mold release system do you use ?
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Old 08-10-2005, 04:37 PM
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Default RE: Thinning Epoxy Resin

ive been trying to promot this resin but no won cares Just use it as you would a polyester resin


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Old 08-12-2005, 06:47 AM
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Default RE: Thinning Epoxy Resin

HI GOONY IS RIGHT.. USE AS AS POLYESTER.. LOOKS THE SAME..THE STUFF IS SUPER.. I HAVE GONE TO AS LITTLE AS 1/4 PERCENT HARDENER WITH GOOD RESULTS..GIVES ME MORE WORK TIME.. 1/2 WOULD BE BEST IF YOU ARE IN A COOL AREA.. OK,,SANDS SUPER,NO TACKY SURFACE, HEAT DOES NOT EFFECT IT,, ANY GLUE STICKS TO IT CA,EPOXY,ECT..CAN BE THINNED WITH ACETONE,MEK,..CAN AD COLOR,PIGMENT,,,WORKS WITH ALL RELEASE SYSTEMS..PVA,WAX.MARBACOAT.SILICONE..HAS JUST THE RIGHT AMOUNT OF FLEX SO THE GLASS DOES NOT ,EGG-SHELL, WHEN FLEXED,, IT TOOK ME A LONG TIME TO FIND A RESIN I COULD RELY ON,,THIS IS IT,,ABOUT $32 A GALLON RD
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Old 08-14-2005, 12:55 AM
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Default RE: Thinning Epoxy Resin

BUT SMELLS BAD!
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Old 08-14-2005, 06:53 AM
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Default RE: Thinning Epoxy Resin

AND IT IS DANGEROUS. ONE DROP OF THE HARDENER IN THE EYE AND IT IS OVER. IT CANNOT BE WASHED OUT QUICKLY ENOUGH. POLYESTER RESINS SHOULD NOT BE ALLOWED IN A DOMESTIC ENVIRONMENT.

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Old 08-14-2005, 12:24 PM
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Default RE: Thinning Epoxy Resin

if you use the cat dispensers properly you couldnt get it in youre eye? unless you were REALLY THICK? and no more dangerous than cyano!

if you put it on a scale of water being 0 and epoxy being 100 then vinylester would be 95and you dont have to weight 24 hours to crack it out or need to post cure it to get the best results you can gel it lay it up and crack it out half an hour later

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Old 08-15-2005, 02:10 PM
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Default RE: Thinning Epoxy Resin

YOU SHOULD ALLWAYS WARE GLASSES AND GLOVES!! OH YA. THINS WITH STYRENE ALSO 10% RD
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Old 08-15-2005, 04:48 PM
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Default RE: Thinning Epoxy Resin

if you use the cat dispensers properly you couldnt get it in youre eye? unless you were REALLY THICK? and no more dangerous than cyano
!

I consider myself considerably less "THICKER" than most people who post on these Forums. I am certainly less "THICKER" than those that have extremely dangerous materials in their house. Just consider the children and the cats!

My logic is this. If this material is never in the house I will never be injured by it.

Ed (The thin one) S
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Old 08-18-2005, 08:38 PM
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Default RE: Thinning Epoxy Resin

This is the method I use but with a twist. I first spray the mold with epoxy primer (Klass Kote) and then lay up the 0.6 oz cloth. That pretty much assures a pinhole free, light, strong, and sandable base for a pristine finish. It's more work, but worth it to me.

I've only layed up one canopy with the cabosil method and it picked up too much weight for my taste.

MattK
ORIGINAL: davidfee

Ok, I see that you disagree with me. That's ok. I've tried a great many things, including what you suggested. I've found that using a layer of 0.6oz glass gives more repeatable results, with less weight gain. And it's adding fibers (strength) instead of just resin.

I like to make my layups pretty dry, as my goal is maximizing strength and stiffness, while minimizing weight. Cosmetics are also important. The layer of light glass works for me. I never said two ounce... I'm talking 0.6oz-1oz. I guess "very light cloth" is a relative term.

-David
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Old 08-19-2005, 07:20 PM
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Default RE: Thinning Epoxy Resin

[X(]STUFF IN THE HOUSE ???..LIKE GUNS!!!!! SORRY ,ITS ,YOUR JOB, NOT TO HURT YOURSELF, NOT THE REST OF THE WORLD...HOW ABOUT KITCHEN KNIVES?? OH MY.. NOT---- RD
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Old 08-21-2005, 08:36 PM
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Default RE: Thinning Epoxy Resin

wait MTK. can you show me a process in which u do this? sounds interesting. what if im using 5.7 oz fabric? and, how long do u wait b4 laying it on?
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Old 08-21-2005, 11:26 PM
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Default RE: Thinning Epoxy Resin

Chelapa, the process is simple, as follows:

Prepare your mold as you would for standard lay-up (wax, PVA spray, etc). Then prepare an appropriate amount of Klass Kote epoxy primer, or primer of your choice, and spray it onto the prepared mold. Let it cure at least 4 hours or overnight if you can, assuming you used the 2 part epoxy or urethane primer. If you used dope primer, then you wait less, bu the primer isn't as bullet proof.

Then lay-up right into the primer, let it cure overnight, and 24-36 hours later, pull the part. Remove the PVA from the part by washing it with soapy water, sand it smooth and then spray paint it with your favorite paint. I prefer automotive urethane acryllic paint such as Concept or Omni, but any paint will work over such a prep

The weight pick-up due to the primer is actually less than spraying primer over the part afterwards. For a fairly large canopy for a pattern model, it's around 7-8 grams, about half of which is sanded off

With the 6oz cloth, use the 0.6 oz cloth first which serves to fill the weave of the heavier cloth far easier. So the layers will be: primer, light cloth and then heavy cloth and BTW, always use a single piece of the heavy cloth if at all possible. No need for heavy overlaps that way. If you used the heavy cloth on the bias, it will conform easier to the compound curves of the mold.

I use Pro Set epoxy. It is the thinnest and easiest to work with that I have found, that is reasonably priced.

Mattk
ORIGINAL: chelapa

wait MTK. can you show me a process in which u do this? sounds interesting. what if im using 5.7 oz fabric? and, how long do u wait b4 laying it on?
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Old 09-07-2005, 11:01 PM
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Default RE: Thinning Epoxy Resin

I thin my West epoxy with 99% alcohol and have great results. It cures a little slower but hardness is not affected, at least not to my measure. I don't know if thinning will have any affect on your pinhole problem but as far as thinning out for increased wetting, alcohol works for me. That goes for everyday life too.
I'd like to hear from others that have had por results with alcohol thinning...could save me some problems.

Lee

ps. For smaler parts that can be baked I find the alcohol evaporates quickly (5 mins so best to let your part evap in ambient temps (30 mins) before baking or else what you put in the oven might not be what get out.
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Old 09-07-2005, 11:22 PM
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Default RE: Thinning Epoxy Resin

i heard the same. i have a good ratio im going to start with ;-) thanx!
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Old 09-07-2005, 11:25 PM
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Default RE: Thinning Epoxy Resin

You need to be very careful when thinning with solvents. The solvent must a) evaporate completely before the epoxy begins to stiffen and b) not dissolve your release system (if you're molding something).

The problem is that condition a is very rarely satisfied... resulting in measurable decreases in physical performance (strength, Tg, etc.). Also, alcohol is terrible in that it is very hygroscopic and the resulting water contamination will really cause problems with the epoxy.

If you need to reduce the working viscosity of your epoxy... just warm it up and use a slower hardener if needed.

-David
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Old 09-07-2005, 11:47 PM
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Default RE: Thinning Epoxy Resin


ORIGINAL: davidfee

You need to be very careful when thinning with solvents. The solvent must a) evaporate completely before the epoxy begins to stiffen and b) not dissolve your release system (if you're molding something).

The problem is that condition a is very rarely satisfied... resulting in measurable decreases in physical performance (strength, Tg, etc.). Also, alcohol is terrible in that it is very hygroscopic and the resulting water contamination will really cause problems with the epoxy.

If you need to reduce the working viscosity of your epoxy... just warm it up and use a slower hardener if needed.

-David

David, I've seen your avatar more than a few times and I know you know more than me but set me right on this.
- Will heating the resin not dramatically speed the cure of the resin? If so it does not accomplish much in wetting potential on larger jobs.

I do agree that alcohol is H20 attractive however below 80% it is not so much so. 99% alcohol will attaract H20 agressively but at a much higher rate it is evaporating.

Perhaps this is a question that can only be answered under controlled experimentation.


Any other opinions?


Lee

Ps. Here's my C114 Tutor Fuse done with thinning. I'll do the next straight and see if I can wet out as light in the end and also have the same strength.
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Old 09-08-2005, 07:10 AM
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Default RE: Thinning Epoxy Resin

If you need to reduce the working viscosity of your epoxy... just warm it up and use a slower hardener if needed.
I totally agree with David. I tell people time and time again that thinning epoxy is detrimental to the end product. Wests Systems own literature recommends that in order to maintain all of the resin's properties the epoxy should not be thinned.

The choice of resin is important here. West systems epoxy is a top quality product. However West's slowest hardener does not give a very long working time, about 45 minutes. I use MGS epoxy resin. The fast hardener allows a 20 min. working time while the slow will allow about 4 hours. The two hardeners can be mixed for the working time of one's choice between those two limits. When glassing a wing I do as David suggested. I use a slow hardener and warm the resin with a heat gun as I apply it. The resin will go on really thin with this method. You will save resin (Money) and weight.

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