Epoxy for laminating

[Mike Thomas]

I'm about to start laminating the back and sides of a Maccaferri "grande bouche" style guitar, and it's my first. I'm using a vacuum press. I intend to use laminating epoxy to glue the veneers, although I believe others e.g Michael Collins, use urea formaldehyde. I know that Greg Smallman uses epoxy to glue the laminations on his guitars. Thanks to John Maddison I have a DVD of Greg's presentation at Playmakers 2009, and on it he stresses the necessity of having an epoxy that doesn't dry "rubbery", and that doesn't need to be post cured at an elevated temperature. In answering a question from the audience, Greg mentioned the epoxy brand he uses, but the sound at that point fell away, and I couldn't be sure what he actually said. I suspect he uses Kinetix R240 resin from ATL Composites in Brisbane, the same people who make West Systems for the Australian market. Can any of the very knowledgable members of this forum help me on this? I would ask Greg Smallman himself, given the opportunity, but I haven't been able to find a contact address. Thanks.

[Nick]

Sorry Micheal I can't help you with your question but as another who builds Selmer style axes (I use solid B&S at this stage)I would be interested in following your build progress. Any chance of a few pics in a new post?
And I have Micheal Collins DVD set and he does indeed use the Urea type glue because of the lack of air to aid curing of 'normal' glues, I never considered Epoxies but it makes sense now you mention it.
What would be the difference between the Kinetix system as opposed to the West's ?

[J.F. Custom]

Hi Mike,

Sorry I can't enlighten you to what Greg Smallman uses, nor any contact or web details for him either.

I do know Urea Formaldehyde was 'the' glue of choice for laminating for some time, however it has been somewhat phased out of general 'hardware' sales now due to the inherent health risks - it's particularly nasty stuff. I believe it is still used in the industry though. Having said that, with Kims warnings on Epoxy use, caution and care needs to be exercised with either.

ATL's glues are high quality. I have used the West Systems and the Techniglue of their range. Both are thermo-reactive and don't require additional heating to set. They also set hard - like brittle hard; not rubbery so should have all the properties you require. They suggest adding their white fluffy microfibre to the West Systems when using as a glue. The mix ratio of five to one is not very forgiving in the west sys though.

The Techniglue is a 'construction' grade adhesive - basically very similar to the West System with the microfibre already added. It has a ratio of two to one and is more forgiving in the mix.

I'm not familiar with the Kinetix at all sorry. I hope this helps.

Cheers,

Jeremy.

[Allen]

I use the WEST System for the epoxy needs I have, and from what I can tell with it's use, is that it dries hard at room temperature, is pretty much the consistency of double cream, so there is going to be good penetration, and is crystal clear.

One of the things that I got from Greg Smallmans talk (I was there) is that he chose some things because of their properties, and others because of the price. He might have a quirky and dry sense of humour, so it's hard to tell when he was serious or just taking the piss out of us. The upshot is that if this epoxy is made by the same people that do the WEST Systems under license in Australia, then it might very well be so similar that it would be hard to tell the difference except for the price.

[Mike Thomas]

Thanks Nick, Jeremy, and Allen for your replies. Nick, I've been following your builds with great interest, and the least I can do is take some photos of mine, and post them for everybody's amusement. When I get to the making stage, as opposed to the jig and mould stage (which is now almost finished), I'll put something here on the forum.
The Kinetix R240 epoxy is described by ATL as a "high performance laminating epoxy.......... R240 resin and hardeners produce stronger, stiffer and tougher laminates than conventional general purpose epoxy systems". Presumably they regard the standard West Systems epoxy as conventional general purpose. As for price, I was quoted, here in Hobart, $176 for a 4.1 kg kit of resin and hardener. It doesn't come in lesser amounts. That makes it considerably cheaper, on a pro rata basis, than the 500ml+hardener West Systems epoxy I've bought in the past.

[Kim]

Smiths all wood epoxy from LMI is really, really good stuff for all things lutherical. It dries hard, strong and clear, the viscosity is quite thin compared to a lot of products allowing for very good penetration even on oily woods such as cocbolo. It has good open time, requires no pre-cure or other process, and the hardener does not smell overly strong which is more than just a passing consideration if you are concerned about your health.

http://www.lmii.com/CartTwo/thirdproduc ... Wood+Epoxy

If using epoxy take my advice, minimum requirements to avoid possible sensitisation issues, wear a good respirator and regularly exchange the cartridges making sure they are graded to protect against fumes from the product. Wear long sleeves, long pants, thick rubber gloves (dishwashing type not thin nitrile or latex as the molecular structure of the nasty stuff in the hardener is know to be so small they offer little protection and may even increase the toxicity due to breakdown as the fumes permeate through) and the big one, KEEP A FAN MOVING FRESH AIR ACROSS YOU ALL THE TIME WHILST MIXING AND WORKING THE UNCURED PRODUCT. Also be sure to leave any epoxy product a very minimum of at least 24 hours before sanding, scraping or machining regardless of how well cured you may thing it is and be sure to wear a dust mask and fresh long sleeved shirt and trousers during these operations and you will be fine.

No kidding, epoxy is great stuff and irreplaceable in many applications, but you really do not want to become sensitised I promise.

A good tip to keep in mind when ever using 'any' epoxy product is to mix the components and allow to sit for 10 minutes and then stir and apply. If using epoxy on hard, dense and/or oily woods, it is best to apply the mixed product to each of the surfaces being bonded and allow to sit for around 10 to 20 minutes before bringing them together. In extreme cases you can even coat each component with a thin wipe of epoxy and allow it to cure completely before applying a second thin coat to bond the components together.

Hope that keeps you out of trouble.

Cheers

Fresh Skin Kim

[Rick Turner]

I'm a fan of the WEST epoxy, and their metering pump system is really convenient. The Smith products are also really excellent, and I'm about to try their CEPS (Clear Epoxy Penetrating Sealer) on instruments as a sealer/tie coat for finishes.

The WEST epoxy is a good sealer under tung oil, but if you use it under clear coats, you must sand it and give it a water wash to get rid of any amines that come to the surface.

[Dennis Leahy]

Hi Mike,

I'll be very interested to see your process to vacuum laminate sides. I have been stocking up on some veneers to try the process myself (as well as laminated backs.) I have done a little bit of vacuum bagging for furniture parts, but I expect there will be some surprises with guitars.

Here is a link to a thread at The Luthier Community, about vacuum forming veneer: http://www.luthiercom.org/phpBB3/viewto ... &sk=t&sd=a (If you're not a member there, please join up - we are good friends with ANZLF and encourage sharing between the forums. You'll also see a bunch of familiar faces there.)

Grant Goltz has built a number of wood veneer kayaks using the process, and he uses Raka epoxy. So, I tried some on my first guitar (as a pore filler/grain popper) and a bit on another guitar, structurally. Raka is a small enough company that I was able to call and get the owner on the phone, and talk to him about epoxies. I knew there were quick and slow epoxies, but not much more. I found out that the chemistry of epoxy is such that there could be hundreds, maybe even thousands of ways to mix the ingredients to get desired results (color, cure time, cured hardness, temperature range, etc.) With that in the back of my mind, I have decided to give the owner a call again before I buy epoxy for a laminated guitar back. In that case, the color does not really matter too much (though it will bleed out through pores in the veneer, and so I will probably use the same epoxy to surface coat.) What does matter to me is how hard it cures. I would want to make sure it was near the brittle end of the hardness scale.

Anyhow, good luck - and please show your work!

Dennis

[Hesh1956]

I'm a big fan of West Systems too and not just because it is a local Michigan product.

What makes some epoxies work well as a pore filler is primarily four things IMHO:

1) The viscosity - you want the epoxy to be thin enough to be easily manipulated and I like to use the term "mashed" into the pores. The mistake that folks, me included, tend to make when pore filling with epoxy is to take the term "squeegee" literally. I use a credit type card which these days is perhaps the best use for a credit card.... Anyway what I mean to say is that folks tend to think that the squeegee action is to smooth and remove excess. Although that is what I do too as the last stages of pore filling the first thing that I do is use the credit type card to mash the epoxy downward into the pores and from several different directions taking care to move at 45 degrees to the grain. I finish up using the card to squeegee (in the verb sense) off the excess and level things out.

Thick epoxies are more difficult to get into the pores. With West Systems I can completely fill even difficult woods in only two sessions.

Note too that when speaking Z-Poxy and System III which are also great pore fillers both of these companies offer "finishing resin" which is what we want for pore filling. Finishing resin has a thinner viscosity than traditional epoxy glue with the exception of some West Systems products.

2) Working time - although we don't need tons of open time to pore fill 5 minute epoxy does make one rush around a bit more than I would be comfortable with. West Systems, Z-Poxy FR, and System III FR all have working times of 30 minutes or greater.

3) Sandability - even though that is not a proper word this is hugely important when selecting epoxies for suitability as a pore filler. All of my favorites above dry very hard, not rubbery like cheap big box store epoxies, and as such they sand well without loading up the paper. An epoxy that does not sand well will be ripped back out of the pores that you just filled and/or you may find your self sanding your ass off longer than you need to.

4) Color - although not a biggie for me the color of the epoxy can be important depending on the woods that you are working with or if you just don't want to be looking at epoxy favoring to see the wood instead.

These days I prefer to just have epoxy pore filler in the pores and not on the surface of the wood so I sand back to bare wood. But many use a wash coat of epoxy to even things up and this is where the color of an epoxy or the age, it can darken with age, can be undesirable.

Now after being so long winded, sorry...., the guys that I know who use double/laminated sides all seem to use West Systems for this. They expect to get some bleed through with porous woods and then just sand the excess back to the wood.

In addition they make and use a gluing form which is nothing more than a solid half guitar shape made to fit EXACTLY into the mold taking into account the thickness of the two sides and glue layer. This form will have fittings for many cauls that are used to snug things up. Fitting exactly into the mold is important with double sides because the sides come off the form so very stiff that you are not going to be able to manipulate, horse, force, wish them into the mold if they are the wrong size.

I've never done double sides although I know that Ervin does and many of his former students do too.

[Rick Turner]

Good info, Hesh, the only thing I'd add is yet another caution about "amine bloom" which bit me in the arse on a couple of guitars we had to strip and refinish because of poor adhesion of the finish to unsanded, unwashed epoxy filled wood.

Google "Amine Blush", and you'll find all the info you never wanted to know...

Apparently, the Smith CEPS stuff does not have the problem and it's designed to literally glue the finish to the wood. Google for that info, too. If it's good enough for the obsessive varnished boat freaks, it should be great for guitars, etc. Smith highly recommends the Epiphanes varnish products, too...

[Dominic]

I just bent and glued and pressed sides for an archtop in one go with fish glue in my side bender. The fish glue dries very hard and glassy, much harder than pva type glues. It has worked out great. There are some pics of the glued sides in the forum from a couple of weeks ago.

Much safer to use than epoxy or urea glues. And cheaper. And did I mention much safer.

Cheers
Dom

[Kim]

Hey Dom,

I remember that thread and it did work well for you. Were did you get your fish glue from??

caution about "amine bloom" which bit me in the arse on a couple of guitars we had to strip and refinish because of poor adhesion of the finish to unsanded, unwashed epoxy filled wood.

Yeah i found out about this the hard way too. How's that for a luck out, i got to find out all about epoxy sensitivity AND amine bloom all in one guitar.

[Dominic]

Kim, try ALS.
Here

http://luthierssupplies.com.au/product_ ... cts_id=884


Cheers
Dom

[kiwigeo]

Hey Dom,

Yeah i found out about this the hard way too. How's that for a luck out, i got to find out all about epoxy sensitivity AND amine bloom all in one guitar.

Kim were you using Zpoxy or West expoxy when you go the amine bloom thing happening?

[Allen]

I've only used WEST's and only ever seen a slight bloom happen when I had flooded a surface. I usually scrape it back so it just fills pores when I apply. Once dry I then hit it with a sharp cabinet scraper prior to finish sanding.

I hadn't really considered what it was at the time, so it was a good read through some of the links that I found by the Google search.

[Kim]

Kim, try ALS.
Here

http://luthierssupplies.com.au/product_ ... cts_id=884


Cheers
Dom

Thanks Dom

Hey Dom,

Yeah i found out about this the hard way too. How's that for a luck out, i got to find out all about epoxy sensitivity AND amine bloom all in one guitar.

Kim were you using Zpoxy or West expoxy when you go the amine bloom thing happening?

Martin,

It was Zpoxy m8.

I hadn't really considered what it was at the time, so it was a good read through some of the links that I found by the Google search.

Do you remember my post about the 'big' fish-eye problem I had when applying the final wash coat of Zpoxy Allen? Yep, my guess is it was in fact amine bloom and my repeated scraping and sanding and then re-applying epoxy over a relatively short period in my efforts to try and get rid of it was most probably the main reason i ended up developing a sensitivity issue. If i had only known then to simply wash it down with soapy water i may have saved myself much grief but despite having worked with epoxy for years, i had never heard of amine bloom until BobC mentioned it during a TruOil thread at the OLF.

One other thing i will mention, amine bloom in epoxy is more common when there is a relatively high count of carbon dioxide in the atmosphere when mixed, during application, and when curing. Yet another very good reason to work in a well ventilated area and to keep a fan pushing fresh air over you and the work.

EDIT: If anyone is wondering, amine bloom is the result of a chemical exchange between carbon dioxide and the chemical reaction which causes epoxy to cure when you mix part A with Part B. The byproduct of this exchange is a type of amino acid which is excreted from the curing epoxy and presents itself as an oily substance upon the surface. This oily substance has the affect of retarding, preventing, or reversing the polymerisation process, or curing, of most finishes which are then applied over it.

Cheers

Kim

[Cleaver]

Hi Mike and hello to all.
I have been lurking for a while and decided to comment on this topic. I have a lot of experience with both epoxy and urea formaldehyde glues. I think UF glue is a much better choice for your application. Of the UF's I think Uni-bond to be the best.
Advantages of UF over epoxy:
Water clean up (vacuum bagging epoxy is a messy )
Easy to mix, very forgiving as far as ratio goes. You can pretty much eye ball the mix.
Thiner glue line than with epoxy.
Better penetration into the wood
Easier sanding
Harder, almost glass like when dried. You can cut yourself on the dried glue shards. I would think this would make it better sonicly.
Things that are basically equal:
While there are health risks they are easily mitigated. I love epoxy but there is that sensitivity thing.
Long open time

Different glues have different properties and there for different uses. For boat building, epoxy, for guitar sides I say UF.
Now I know a lot of "name" builders use epoxy for laminations but that is just because they don't know differently. I am trying to convince a couple of them as well. Try the UF, way easier and better end product.
Cleaver

[John Maddison]

... I have a DVD of Greg's presentation at Playmakers 2009, and on it he stresses the necessity of having an epoxy that doesn't dry "rubbery", and that doesn't need to be post cured at an elevated temperature ... I couldn't be sure what he actually said. I suspect he uses Kinetix R240 resin from ATL Composites in Brisbane.

Your ears didn't deceive you Mike; that is the product type.

[Mike Thomas]

Thanks everyone, I'm overwhelmed by the responses. Taking some of them in turn:-
Kim, the warnings about the toxicity of epoxy are well taken; I shall try to be careful. The Smiths epoxy looks useful, and is also recommended by Rick

In fact, Rick, I believe, gets the credit from LMI for putting them on to Smiths. And thanks Rick, for the warning about amine blush. It is something I was not aware of. Dominic says in one of his posts, that the amine problem is a consequence of a reaction between the resin, as it cures, and carbon dioxide, presumably atmospheric. Maybe in a vacuum there isn't enough co2 for this to happen.

Hesh, I had thought of the laminating process as being quite divorced from the pore filling/finishing process, but a moment's reflection leads me to realise that in vacuum pressing the laminates, there is going to be quite a bit of pore filling going on at the same time. Laminating epoxy is very thin, like finishing resin, so I might be killing at least one and a half birds with one stone.

Cleaver, thanks for joining in for the first time. I am still seriously contemplating using urea formaldehyde. I think a comparison test, at least, is warranted. Dominic, I have no experience with fish glue, but I have with hide glue. An excellent glue for many purposes, but I think not enough working time before it gels for this particular process using a vacuum bag.

Dennis, I am going to try laminating the sides in the same way that Michael Collins does it i.e glue the veneers and put into a vacuum bag. Switch on the vacuum pump whilst the bag is on a flat surface. Check that everything lines up o.k. The whole package is still quite flexible, and will easily conform to a side mould. Clamp the package to the mould, with the vacuum still on, and leave it until the epoxy has cured.

Finally, thanks once again John for your help. The transcript of the relevant bit of Greg Smallman's presentation was extremely useful, not only for me, but I trust also for others.

[Kim]

Dominic, I have no experience with fish glue, but I have with hide glue. An excellent glue for many purposes, but I think not enough working time before it gels for this particular process using a vacuum bag.

Mike,

Fish glue has a very long open time, it comes as a liquid and is not heat thinned as is hide glue.

Cheers

Kim

[Mike Thomas]

Thanks Kim. It's always nice to learn something new.

[Rick Turner]

I'm still trying to learn something old!

[HiString]

Mike,

When either applying veneer to or making (ply) drum shells from scratch I've always used Techniglue. Veneering shells was always done with a vac bag with no problems, just leave it under vacuum for as long as possible (approx., 24 hours).

If your veneers are the usual 0.6mm then watch for the possibility of unwanted bleed through of the glue..........this is one reason I liked the Techniglue, it's higher gel like viscosity seemed to limit the chances of bleed through.

ChrisO

[Rick Turner]

If you're using an epoxy to laminate and then seal under finish, it doesn't matter if it bleeds through. The wetting of the wood will be even.

Steve Smith has an interesting explanation of why epoxy does such a good job of "popping" figure. To paraphrase him, the epoxy helps draw light down into the wood, and makes the wood translucent, so the refractive qualities are greatly enhanced. Using stains or dyes can actually lessen the chatoyance of figured wood even as it emphasizes grain undulations. So for a macro effect, you can "enhance" the grain by staining, then sanding back so the stain only shows in the end grain waves, but doing this also cuts down on the depth of the look in the long run by obscuring some of the light as it refracts in and reflects back out of the wood.

[Dennis Leahy]

... I have a lot of experience with both epoxy and urea formaldehyde glues. I think UF glue is a much better choice for your application. ...
Advantages of UF over epoxy:
Water clean up (vacuum bagging epoxy is a messy )
...
Harder, almost glass like when dried. You can cut yourself on the dried glue shards. I would think this would make it better sonicly.
...
Long open time

Different glues have different properties and there for different uses. For boat building, epoxy, for guitar sides I say UF.

Cleaver

You make a strong case for UF. What if the face veneer is very porous? (such as burl) Or something like a Karelian Birch burl, where the glue would easily come through in some places but not in others.

...If your veneers are the usual 0.6mm then watch for the possibility of unwanted bleed through of the glue..........this is one reason I liked the Techniglue, it's higher gel like viscosity seemed to limit the chances of bleed through.

ChrisO

And that bleed-through was what made me think that the ideal pore-filler and possibly a thin surface treatment to "pop the grain" would be the same material as the glue. Some of the veneers I have started collecting are burl, and there is 100% certainty that the glue will come through.

If you're using an epoxy to laminate and then seal under finish, it doesn't matter if it bleeds through. The wetting of the wood will be even.

You make a strong case for Epoxy. See how easy it is to bounce back and forth between competing good ideas?


Thanks for the topic, Mike! I may be a year away from trying laminating (I have a bunch of non-laminated guitars on the front burners), but this is really helpful to start to plan the process.

Dennis