Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[ianmcairns]

I have just finished the double-planked hull of the Anteo tug and have attempted to epoxy it with tissue mat as per the Cervia Tug masterclass instructions and other posts on the forum. It is the first time I've tried epoxy and it is a total disaster. I have ended up with probably every possible beginners mistake from lumps where the stuff started suddenly going off and I couldn't smooth it out to patches with no epoxy or tissue showing where I ran out of resin mix.

What's the best recovery plan? Obviously I can sand off the bumps but what about the holes and tissue patches? If I put another layer on will it smooth out the depressions or will I just end up with the same situation under a thicker layer! Or should I give up, sand it back to wood and try again a little wiser?

[DickyD]

What type of epoxy did you use ?

[ianmcairns]

It's Zap Finishing Resin - OK stuff I think - blame the operator!

[Subculture]

Not used that brand. My experience with epoxy has been that unless you're working in very hot conditions, the pot life gives plenty of time to work the laminate. Are you mixing too much up in one go perhaps?

I would just sand back the bad areas, recoat with another layer of glass and resin, and once cured fill in any depressions with polyester filler. It'll be more than strong enough, and who's to know once you have a coat of paint over the top?

[HS93 (RIP)]

use the 0.6 oz cloth and the AEROPOXY no problems with them nice Finnish rember leave the cloth bigger as it shrinks when the epoxy goes on helps get rid of wrinkles

http://www.deluxematerials.co.uk/pages/clothsandresins.htm

Peter

[CF-FZG]

... rember leave the cloth bigger as it shrinks when the epoxy goes on helps get rid of wrinkles

Epoxy won't shrink glass cloth, it just makes it stiff.  The aeropoxy instruction say to thin it with 50% meths, why??  If it's laminating resin is doesn't need thinning.

The ones I'd recommend are the Z-Poxy finishing resin mentioned above, and my preferred one which is L285, a resin used by full size boat builders.


Mark.

[HS93 (RIP)]

Epoxy won't shrink glass cloth, it just makes it stiff.  The aeropoxy instruction say to thin it with 50% meths, why??  If it's laminating resin is doesn't need thinning.

The ones I'd recommend are the Z-Poxy finishing resin mentioned above, and my preferred one which is L285, a resin used by full size boat builders.


Mark.

ok it must make it disappear well it did on the last fire boat we coverd, we cut it well over size and as we started working the  epoxy  in it just disappeared around the edges it must be Magic.

Peter

[andrewh]

Hi, Ian

To try and answer your question

What's the best recovery plan? Obviously I can sand off the bumps but what about the holes and tissue patches? If I put another layer on will it smooth out the depressions or will I just end up with the same situation under a thicker layer! Or should I give up, sand it back to wood and try again a little wiser?

Yup, sand it clean and sanitary again, and do it again with a smaller mix.  I think Anteo is a big mother - and I Know that you mixed up a fairly large bulk in a deep container, like a cup.  Am I right?
ZAP is a very reputable brand, and will behave beautifully next time

Before mixing (and before your hands are goopy and sticky) cut out all the glass, and lay it out in order of use - you can (if you wish) give the hull a LIGHT spray of spraymount to hold the glass in place

Mix in a shallow container (I use a shallow polythene bowl made for this  - from the Fibreglass Shop)
You cannot mix too well

Most epoxies at room temperature will give you about 30 to 60 minutes of working time.  If you get less then you probably have been sold the winter catalysy (unlikely) or the temperature has "run away" more likely
hope this helps
andrew

[ianmcairns]

Andrew and others thanks for replies. Yes I mixed up in deep container. Too much stuff and too warm. I told you every beginner's mistake!

Here's where I've got to. The white patches are dents where the tissue is surfacing and collecting sanding dust. It's going to be a helluva job getting this back smooth, especially on the curves and yes it's a big mother - hey ho.

[ianmcairns]

Thinking ahead - do you have to use a special primer paint on epoxy?

[andrewh]

Ian,

In theory, yes; but in practice if you have flatted it down with 1000grade wet and dry (used wet) NO

When cured and flatted it is pretty chemically inert (again in theory)

By the way - when sanding epoxy (and when working with it) please protect yourself, skin and lungs - at the very least long sleeves and a facemask
andrew

[Welsh Wizard]

No You should be ok with anything you throw at it,never had a problem with ANY form of Epoxy


Dave

[John W E]

ianmcairns hi there

Couple of things - if you read the Cervia build in full - you will realise that I used a POLYESTER RESIN along with TISSUE matt to cover the hull with.   Not Epoxy resin

These two resins are totally different - the high possibility of the fault of the lumpiness/bubliness/finish is that tissue matt which is used with polyester resins, is not to be used with epoxies.  The reason for this being that when the manufacturers make up the chopped strand matt/tissue matt - they bond the elements together with a bonding agent which in turn breaks down to release the fibres when coming into contact with a polyester resin.   Epoxy resins wont break the bonding agent down - therefore then you know the outcome.

If you look at how the flyboys (when they build aircraft) they always use a fine woven/roven material which doesn't use a bonding agent to hold it together - the actual weaves of the material do this job.  Also, they are able to achieve a superfine finish with using an 'old credit card' to spread the epoxy over the material - you cant use this method when working with chopped strand matt/tissue.

What I suggest you do is acquire some aluminium oxide paper of about 40-60 grit - to take off all the 'affected' areas and basically take it back to the timber to start over again.   Then either use an epoxy or a polyester resin but remember DONT MIX THE TISSUE MATTING WITH EPOXY.   

As an afterthought though if you double plank this hull, you should be able to fill any dents/mistakes with card body filler P38 or similar - sand it smooth and put two coats over the top of epoxy resin - you will find that will be sufficient to seal the hull.

aye
john

[andrewh]

Well, down me blow

I had totally missed the part where you said that you had used tissue mat.

John is (as ever) totally right - its made with E glass specifically for Polyester resin and at the very least will remain stiffly refusing to lie down for you with epoxy.

Yes - finishing cloth is the stuff  - laid on the bias if needed to drape elegantly ofer the hull
I usually apply dry (sometimes with a light huff of spraymount) and squoooge the epoxy through it with a nylon polyfiller blade and latex gloves

andrew