Epoxy & Meths

[clyst]

Got a small epoxying job to do , problem is I'v only got access to chopped strand matting (polyester use) .Job entails envolves using the CSM in 2 1/2 in strips. Because epoxy is a bit "gloopy" to use straight on CSM I propose to thin the first coat down with drop of meths . What do you recon , do you think for a first coat it will bond well ? Good idea or not ?

Cheers

Terry

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[jeanne]

Chopped strand mat has a 'binder' which disolves in polyester resin, to leave the glass flexible, and able to be shaped to the form needed. Epoxy will not disolve this binder. Woven mat has no need for a binder, and this, as far as I know, is the only form of glass to use with epoxy.
As for adulterating the resin with meths: why do you think you know more about resin than the guy in the company which makes it, who has spent his life working with the stuff?

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[clyst]

Well smack my wrist !! Dont use epoxy much do you? I wanted advice not sarcasm!!

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[bruce]

stuff should not be 'gloopy' but wet and smooth, am thinking that yours has aged past its shelf life. i have always had problems using lumpy, never seems to set up right, often cracking as it sets up. check www.westsystem.com for more answers.

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[floatything]

Whenever I use meths to clean out my epoxy pot - even a small amount seems to turn the whole lot to a lumpy liquid / - so I suspect you might have a problem getting the consistency right using meths. I think the main issue is not so much the consistency of the epoxy - rather the binder problem with CSM as others have pointed out. Is there no way you can use woven mat for this job ?

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[waverider]

What is the detail of the work you want to do Clyst that GRP won't handle?

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[Joe_Cole]

I don't think that he was being sarcastic; it was a perfectly fair question to ask.

If you want advice though........Don't do it like that.

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[clyst]

With due respects having re read the last para of the post ref implying that Iconsider to know more than the manufacturer I still consider it to be written and ment to be a sarcastic remark. A "fair question to ask" ??all I wanted to know if it was considered acceptable to dilute epoxy with meths in this application. Its a well known dodge to dilute epoxy with meths to make it "runnier"when saturating wood .

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[waverider]

Got a point there.....for the past months I have been carrying out a complete refit and modifications to a Seal (loving every moment of it!) in my project I have made plugs and moulds, welded....crafted and polished stainless fittings...carried out a rewire.......cut and shaped expensive sapele mahogany (without too much waste!) and just thought I might be able to help or give little advice!

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[waverider]

clyst.....what are you making or repairing?


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[Guest]

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[duncan]

I am with Brain on the cop out and Jeanne on the CSM - sarcasm or not (personally I think the question asked was answered honestly and constructively)
The meths should make the resin easier to handle but I don't see how it will improve the binding with the CSM?

<hr width=100% size=1>madesco madidum ..../forums/images/icons/smile.gif

 

[clyst]

Bonding a "floor" in a Silhouette. It consists of a wooden block"strapped " to the hull with 2x 2 1/2in strips (one p&s) of matting . Have to do it tomorrow only have access to materials on site as described in original post . Not ideal I admit thats why I asked .

Cheers
terry

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[clyst]

Cheers Fatipa for that just what I wanted to hear . Many thanks??
Cheers
terry

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[clyst]

Yea, I appreciate the advice about the bonding agent and take that on board , its the commemt implying that "I knew best "which peed me off . Far from it thats why I asked !

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[William_H]

And lastly heating the epoxy will make it runnier. It will of course make it go hard quicker so be carefull. Agree that Chop strand mat may not take the epoxy too well. So try it first. regards will

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[oldsaltoz]

G'day Terry,

This sounds like an emergency repair, given that you plan to use only what is available and not wait for the correct materials; so here are a couple of things you can look at doing.

Firstly, the bonding agent in CSM is not that strong, so if you roll it with a sharp threaded roller with pressure you break up most of the bonds, this will crush the mat to a better profile for epoxy resin, about 8 or ten passes should help, keep plenty of pressure on.

I would avoid thinning, with the amount of rolling required the resin will get through, make sire you precoat the area before applying the strips.

Epoxy resin should be only 50% of the total volume, normal resins are 75% of total volume. You can get close to this by laying up one strip, heavy rolling then after waiting about 20 to 30 minutes, apply some heat, a heat gun or hair dryer will do, hold a credit card at about 30 to 40* and press the excess resin out as you drag it over the surface, keep the card clean by frequent wiping.

If your timing is right you should see a smooth finish, almost polished look.

Just make sure you have very good ventilation and an extinguisher handy.

The above is NOT the right way to do this work, but given you plan to do it anyway, I hope this helps.

You can recoat the whole thing with the correct materials when they are available, but I would not leave it too long.

Avagoodweekrnd.............

<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.

 

[Trevethan]

In the past I have used csm and epoxy -- before I was told differently. Its a bugger to use, but can be done.

I filled in an old hatch opening and it seems fine 2 years on.

Paint up area where you wish to apply with resin and let it go off. Sand it back the put a second coat on. Let that go a bit tacky and then place sheet of mat onto it and roller into place. Paint on some more epoxy, and fair back



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[clyst]

Cheers Trevethan, That more or less what I'v done seems to have wetted out ok it all went "transparent" anyway so should be OK .

Terry

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[Guest]

I used to do this when building Radio Model aircraft ....
But first I used to smear a film of unthinned epoxy over the area and then lay the CSM on it. Then using the thinned epoxy ..... stipple it in so that the underlying epoxy was bonded to. I found it interesting that some epoxy's turned blue when meths was added !!

But obviously the strength and character of the epoxy is less when thinned with this .... so building up a good wet-out is essential and a final layer over the top of unthinned epoxy ...... basically sandwiching the csm and thinned .....

<hr width=100% size=1>Cheers Nigel http://groups.yahoo.com/group/gps-navigator/ http://groups.yahoo.com/group/searider/