bmoney69

My Feedback: (2)

does it matter what alcohol is used to thin z-poxy for laying up glass? isopropyl or denatured? i used iso 70% and let it sit overnight and the leftover in the bottom of the cup is still very rubbery and comes apart very easily, like it has no adhesion properties. i was very careful to mix the exact portions and the 30 min z-poxy is brand new. any ideas?

Ed Smith

Do not thin epoxy ever. Thinning with anything alters the structural integrity, as you have just found out.

Ed S

bmoney69

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thanks for your post. i know i've done this before without a problem. is there anychance it will harden in a couple days, weeks, etc? the reason i ask is that i can't simply unring the bell here. is there anything i can do moving forward?

daven

My Feedback: (1)

I've thinned with the 99% stuff and its worked ok, I've even thinned with Acetone and thats worked also. I tend to avoid it for the reasons stated by Ed above, but for firewalls or tank compartments its worked fine.

I'd give it a couple days and see what happens. Worse case, heat with a heat gun and see if that helps, or remove and start over.

bmoney69

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yup...thanks guys....i'm going to hit the unused portion with a heat gun and see if that helps...if not, it shouldn't be too difficult to remove since i thinned too much.

R8893

My Feedback: (20)

I suspect your problem is that the 70% isopropyl alcohol is 30% water. Water and epoxy are not a good mix. I don't thin Z-poxy anymore, but when I did (for use as finishing resin) I found that methyl alcohol (the stuff you burn in a glow engine) gave very good results. I thought it cured to a harder, more easily sanded surface than when I used 100% isopropyl.
Chuck

G17Staggerwing

My Feedback: (159)

There are several articles on using finishing epoxy thinned with 40% denatured alcohol as a glassing method on aircraft and boats. In fact I am planning on using that method with an airplane project I am presently working on. As the other gentleman stated I wouldn't thin out the epoxy if I were using it for strength area either, but as a saturating method to applying fiberglass cloth it is excellent. I think your problem lies with the wrong alcohol type. The article also states that after you have completed you glassing to us a light weight household spack to fill any pin holes with.
Regards
Nevin
G17Staggerwing

bentwings

I've used Z-Poxy for a long time for finishing only. I use denatured alcohol from Home Depot or other home stores. This is as pure as it gets. I use about 30% added after well mixing the resin and hardener. I also use small amounts at a time. Never more than 1 ounce or so. If you mix up more you need to put it in a shallow dish or it will set too fast. I use old credit cards as spreaders and occasionally wipe up the excess with soft paper towels. It makes a sticky mess but it is the best way to get the excess off tight spots. I use two coats with only a very light sanding or scuffing between coats. You should really recoat within a couple hours to get really good bond between coats.

I also use the light weight spackle. I like to use a pre coat of Z-Poxy on the fillets and larger ares that have been filled. This seems to soak into the spackle and prevent it from cracking. It works for me.

TeamSeacats

chances are that it's not going to get any firmer. If it's just for sealing a firewall, it should work even if it's a little gummy. I very rarely thin epoxy - but I use a laminating epoxy that is considerably thinner than the hobby-store 30 minute type. If you get a West System or similar laminating epoxy, it will brush right on with no need to thin it. When I thin it, I use denatured alcohol and thin it as little as possible.

Campy

My Feedback: (1)

If you ABSOLUTELY HAVE TO THIN EPOXY, do these in the following order:

1st try heating it with a heat gun. Frequently that will thin it enough for easy spreading.

2nd, if you need to actually thin the epoxy use ONLY denatured alcohol, acetone or 100% isopropyl alcohol. Regular isopropyl alcohol contains water. Water and epoxy do not get along well with each other.

In any case, thin up to 5% BY VOLUME and NEVER EXCEED 10% BY VOLUME. Above 10% thinning creates a VERY long time to cure and radically weakens the epoxy.

Starfighter

My Feedback: (78)

Hi. Here's my 2 cents:

I have had this happen to me in the past when I grabbed the wrong Alcohol. You see, Isopropyl Alcohol is avail. in two solutions: 70% and 91% Alcohol with the remainder De-Ionized Water. The water is the problem, and as stated by others above.
When thinning Epoxies, please make sure to use only Denatured Alcohol, or Acetone (Acetone evaporates too quickly tho).

This may help to firm up the epoxy that seems 'rubbery' [this assuming that the initial mix ratios were correct in the first place] and has worked for me:

*Take the acft. outside, or to a well ventilated area. Using a heat gun set on high, heat the area thoroughly until the surface is hot, but don't burn it. Let cool, see what you have. If needed, do it again, maybe even several times. The epoxy may even start to 'smoke', and as long as it is not burning, what is happening is that it is 'gassing off' and a lot of water vapor is going with it. After you do this, you may find that the epoxy hardened. Then, after you have a result that is acceptable to you, saturate the epoxy(and surrounding wood at the joint) with thin CA. Let it sit untouched for a while(sometimes as long as an hour) so the CA cures slowly and w/o Kicker. This will really harden the area, and if the CA is still a little 'tacky' after the 1 hrs. time, then hit it lightly with Kicker (Bu,t don't kick it off while it is still wet. The thin CA gets brittle when you do that.).
This should result in a harder and more solid surface that will tale another coat of epoxy if you wish. (Epoxy cures w/o problem over CA.) IMHO

Take it easy, Buddy.

Ken (Starfighter)

bmoney69

My Feedback: (2)

ok, thanks for all the input fella's.......that solves the mystery for me, i just dindn't understand how alcohol would do this since the idea is that the alcohol would evaporate....well, it's the water that caused the problem...thanks for pointing that out!

here is what i have.....the epoxy that is actually in the plane has dried to an acceptable degree after two days and some heat gun treatment. it dried to the point that it wasn't tacky and i could give it a light sand. i tried pealing up some of the edges of the glass and i couldn't so that's comforting. i then mixed up a batch of fresh z-poxy with no additives, heated it up and gave the whole area a good coat. i'm going to call it done and work on finishing the exterior. it's in an area that i can see easily and i'll just keep a close eye on it to make sure the engine vibration isn't causing it to de-lam over time.

i'll keep you posted. thanks again!!

Bill

John Sohm

My Feedback: (9)

Campy, in response to your #1 statement, I hope if while using this method you are using a respirator or doing it outdoors. Most people think that because epoxy doesn't smell as bad as polyester resin or dope for that matter, that it isn't too bad for you. Talk to anyone involved in the epoxy industry and you will find that the fumes emitted by epoxy are actually more detrimental to your health than those of the other items mentioned here. Epoxy is one of those items that, over time, you can build up an intolerance too very easily and just the fumes can trigger severe dermatitis if not used with care. I always use gloves when handling epoxy just to prevent that from occurring and use it in a well ventilated environment. After glassing a wing or some other large surface, I exit the area afterwards and allow it to cure completely before I return. I know this might sound a bit extreme but I don't want to develop any type of lung condition either, it's bad enough with the little bit of asthma I have, I don't need to agrevate that. I hope all that read this post tend to take this seriously for their own health's sake.