High pressure Laminate guitars

[SOLR]

From Gerry Haze of haze guitars , another interesting blog post:
S



Hey again
I recently had to do some work on a guitar made from High-Pressure Laminate and, as it's becoming more common, I thought the merits and drawbacks of that material might be worth discussing. I’ll also touch on the repair I did to illustrate things.
Before I start though, this is not a discussion of tone. If we start down that road, I’ll be here for the next year, refereeing arguments between the warring factions. If you want to talk tone, there are plenty of forums where you can do that until every single cow has come home. Go nuts.
So what is High-Pressure Laminate?

Well, to be honest, I have to come clean at this point. While I know a little bit about wood I don’t know a heck of a lot about HPLs (High-Pressure Laminates).
That said, I’ll try to summarise what I know and — I think — what you need to know*.
HPLs are made from a number of laminations or layers of what is, essentially, paper. It’s slightly different to the paper we use every day but, for all intents and purposes, it’s paper.
There’s generally an overlay layer, sitting over a ‘decorative’ layer (more on this in a sec), and then one or more layers of a stronger paper.

These layers are impregnated with a phenolic resin and are heated while simultaneously being pressed at up to 2000 pounds of pressure per square inch.
The result is a thin sheet that’s very hard and very tough.
For an everyday example of HPL, chances are your kitchen counter tops are covered with a HPL material. Formica is one, well-known, brand.
*Actually, I lied — you probably didn’t absolutely need to know the ’sciency’ bit but I reckoned it would be useful as we went on. The following stuff, you probably do need.
What do kitchen counters have to do with guitars?

More guitar builders are beginning to offer instruments using materials other than wood. Martin Guitars, for instance, have widely embraced HPL materials and offer a number of models where some — or even all — of the back, sides, or top are made from HPL.
While a Spinal Tap None-More-Black colour is popular, HPLs for guitar use will often have a wood-grain pattern printed onto that ‘decorative’ layer we mentioned earlier. The overlay layer can also be textured to feel a little more ‘woody’ if the builder wants to play that up a bit.
The pros of HPL

So what are the good points?
Manufacturing

Well, from a manufacturing point of view, working with HPLs is likely much more consistent and predictable. It’s almost certainly considerably cheaper, from a materials and an assembly point of view too. Full disclosure: I don’t know either of these things for sure but I reckon it’s a safe bet. Happy to be corrected.
This manufacturing saving means you can often buy a HPL guitar more cheaply than its wood stablemates.
As a slight aside, from a wider manufacturing point of view, the move to more sustainable guitar materials is well underway and we, as players, will have to get used to it. For many reasons, wood will become less-used in musical instruments. While many will decry this, there’s very little they can do so, it seems sensible to make peace with it.
If you’re a wood purist, that’s cool, but you’ll probably have to get used to paying more for your instruments and understanding that those instruments may come with restrictions. But, back to the main story…
For the player

“I don’t care about how easy or hard it is to build a guitar,” you cry, “what’s in it for me?”
Well, HPL isn’t subject to the same whims and idiosyncrasies of wood. If you live somewhere where the environment hates guitars, this is a godsend. Very wet and very dry environments will hold less danger for the HPL instrument.
Within reason, a HPL instrument can get wet without too much hassle. The surface is super hard and it will laugh at scratches, pick-wear, etc. It will handle heat better than a wooden instrument.
There’s no actual ‘finish’ so there’s nothing to crack, or check if it gets too cold. You can probably pour a selection of household chemicals over it without any damage (although I’d probably still try to avoid that — for many reasons).
If you want a guitar to drag around without worrying too much about scratches, or rain, or heat, or humidity, or dryness, these instruments could be just the ticket. Obviously, this isn’t an invitation to stress-test a guitar to destruction but HPL guitars should hold up to environmental hassles better than an instrument made from a dead tree.
The cons

So what’s the problem with this wonder material? Well, other than the ‘not-wood’ issue that bugs traditionalists, there are two main problems.
Hardness as a weakness

The first is that, while HPL is incredibly tough in one sense — you won’t scratch it, or soak it, or all of the other things listed above, but…
It’s hardness makes it somewhat brittle.
When it’s bonded to a kitchen counter, that’s not so much of a problem but, when it’s made into a guitar shape, and dragged around the world by musicians, a good whack in the wrong place/direction and you can end up with a heap of shattered HPL pieces.
And shatter is a good term.
Yo'll be left with jagged, irregular shards of material that resemble a guitar jigsaw.
And that brings me to the second problem.
It’s not terribly repairable

HPL (at least in guitars) is not really made with repair in mind.
Now, let’s face it: if you whack your wooden guitar, you may well break it too.
Buuuuuut… The nature of that instrument lends itself more readily to repair. The sides, top, and back are generally thicker and can be more easily glued (and wood glues are typically friendlier and more forgiving to work with). Wood itself can be shaped, and formed, and bent. Dings and dents can sometimes be lessened or removed altogether. And, since most wood-built instruments have a finish of some kind, evidence of repairs can often be hidden or minimised.
We get none of that with HPL.
The material is usually very thin and difficult to butt against neighbouring pieces. Not that that matters because, if HPL does break or shatter, the laminations will often break ‘separately’. That is, different layers will break in slightly different places and in irregular ways. Fitting shattered HPL back together can sometimes be impossible.

To show what I mean, the image above illustrates (and exaggerates) the way different layers/laminations can break differently. Imagine that happening with all those layers sandwiched together and you have some idea of the problem.
Compounding the repair hassles, even if you can make some attempt at reassembling your jigsaw, it won’t ‘support’ itself.
In the photo below, for instance, I had to bend a piece of mahogany to act as a ‘former’ inside the guitar side. I glued this shaped piece to the inside of the guitar side and built my jigsaw on top of it. Similar story for the back section.

And, when working with HPL, lovely friendly wood glues are out. I've learned from Beau Hannam's splendid YouTube channel that Martin recommends 3M Scotch-Weld PR600 for bonding HPL. You can see Beau re-glue a back and side separation in the linked video. That's fair enough for back and side separations but I didn't want to go with any sort of CA for this splintered side situation. So, epoxy is the order of the day and that is — not to mince words — a pain in the ass.
Lastly, forget about minimising the signs of a repair. Quite the opposite. There’s no finish to provide some camouflage and, because it’s so incredibly difficult to get shattered HPL pieces to mate nicely, there’ll be high and low spots that have to be flattened down. That probably means you’ll sand through the overlay, and even the ‘grain’ layers, so it’s going to look ugly as sin.
HPL repairs are the Frankenstein’s monsters of the guitar world.

Seriously. Do you think I like showing you this photo? Even though I made the limitations incredibly clear to the owner before I started, do you think I liked handing that back? I’m an anxious, uptight perfectionist and it makes me very, very sad that this is the best I could do with this guitar.
Because it’s almost impossible to make a good job of HPL repair (and because, let’s face it, nobody likes paying for something that’s not a good job), I often turn away HPL repairs. This one was a special case.
Many other repairers are in the same boat. It's a lot of messy, fiddly work, which means it's not cheap. And it's a tough to hand over a scarred mess and take money with a clear conscience (even if you feel you've done the best job in the circumstances)
The bottom line

HPL guitars have a lot of advantages. Seriously. Despite my whinging, I think they have a lot going for them and no one should disregard them. As well as their toughness merits, it can be a more affordable way to buy an instrument (or buy into a more expensive brand).
I’ve seen heaps of Martin HPL guitars, for instance, and they’ve all been well made, nicely playing, good sounding instruments. You do yourself a disservice if you discount them through snobbishness.
However, go into this with your eyes open. Bear in mind the potential risk should the worst happen.
And, if you do end up with a heap of jagged guitar-jigsaw pieces, be aware that repair will probably be very difficult. If you can find a repairer to take it on, cut him or her some slack. They’ll be attempting the almost-impossible.
I hope this hasn’t been too much of a downer. I think it’s good to be informed, though. Hope that’s ok.
Cheers
Gerry
?
P.S. It definitely needs to be said that instruments made with laminated wood can also have 'mismatched splintering' problems if they break. Plywood guitars can also be problematic for crack and break repairs. This is particularly true of newer models with very thin, very satin finishes. However, despite their repair challenges, laminate wood instruments are still easier to repair — and easier to hide repairs on— than HPL. The owner of the instrument below didn't want the added expense of involved touch-up but (while it's very far from my most discreet repair), the evidence of damage can still be minimised.

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Rossberry Avenue, Lucan, Dublin Ireland

[garybaldy]

Presumably, flat sheets of HPL can be further shaped to form arched tops, backs and sides; or does the HPL have to be made in the shape of the guitar parts (by the luthier)?

[Cunamara]

Astonishing. I did not even know this was a thing.

X-Series | C.F. Martin & Co.

I am tempted to dismiss it out of hand, but maybe if I saw and played one of these instruments I'd have a different opinion. Or at least be better informed before I dismiss it out of hand.

[SOLR]

Presumably, flat sheets of HPL can be further shaped to from arched tops, backs and sides; or does the HPL have to be made in the shape of the guitar parts (by the luthier)?

Hi, I reposted this blog from Gerry , your question should perhaps be addressed to him directly : Haze Guitars Repair — Haze Guitars

BTW amazing repair on the laminate one

[COLOR=#C3BEB6 !important]P.S. It definitely needs to be said that instruments made with laminated wood can also have 'mismatched splintering' problems if they break. Plywood guitars can also be problematic for crack and break repairs. This is particularly true of newer models with very thin, very satin finishes. However, despite their repair challenges, laminate wood instruments are still easier to repair — and easier to hide repairs on— than HPL. The owner of the instrument below didn't want the added expense of involved touch-up but (while it's very far from my most discreet repair), the evidence of damage can still be minimised.[/COLOR]

S

[Archie]

This material has been around for along time and is used most commonly in decorative construction veneering.
Counter tops are made out of many composites, Richlite being one. The stuff Gibson started using instead of ebony.

The claims made on conservation grounds is tenuous. I would imagine guitarists have been told to 'suck it up' by the green lobby regarding wood replacements, since time and memorial.
The truth is, Maple is in abundance and in many countries considered a weed. There will be no shortages. The same for Spruce's. Exotic woods always come and go but domestic sustainable options will always be available (famous last words).

HPL is not environmentally friendly in the least given that it doesn't degrade, especially the epoxy. Don't worry, if everyone changed to HPL the price would go up and the same people telling you wood is bad, will be telling you HPL is even worse.
Guitars made from it would likely have very thin tops and an equally thin sound. That can be manipulated of course.

Still would you rather have a hump of plastic of a wooden guitar? (granted epoxy is used in laminate wood construction but if you keep the layers down, the use of epoxy is at a minimum).

[Rickco]

I wasnt aware HPL was used in guitar construction, HPL is "Formica" my company fabricated acres of it over nearly 50 yrs cant imagine it being used for guitars it was developed for counter tops.

[Sam Sherry]

HPL is not environmentally friendly in the least given that it doesn't degrade, especially the epoxy. Don't worry, if everyone changed to HPL the price would go up and the same people telling you wood is bad, will be telling you HPL is even worse.

"Old epoxy is good epoxy."

That stuff doesn't grow on trees y'know!

[Archie]

"Old epoxy is good epoxy."

That stuff doesn't grow on trees y'know!

it really opens up over time too. The old HLP's always sound better than the new ones

[Rickco]

it really opens up over time too. The old HLP's always sound better than the new ones

Especially the ones with printed wood grain!

[Archie]

Especially the ones with printed wood grain!

Imitation mahogany will need a CITES in a few years.

[Rickco]

HPL is also known as plastic laminate and for a long time generically called "Formica" developed initially for things like circuit boards soon its durability potential combined with its insulation properties made it perfect for work surfaces in labs and electronics work surfaces. Formica was first to promote it for counter tops and enclosures. It hit its peak as an interior furniture material in the '80s with the slick "Euro" look. Popular in interior fashion for a while was the "Memphis look" which was mostly laminates. OK heres the cool part... Remo Belli (Remo drums) was one of the first to do it in shaped parts. His whole line of hand drums are made of HPL and he designed the equipment to form and fabricate almost any shape. I was privleged to spend a day at his plant with him where he treated me an in depth tour of the processes. The drum line is very successful so the material must be capable of resonating. If the guitar makers are making flat parts thickness would be controllable but most of all you could put your guitar in the sink and wash it if it were soiled or use it for a paddle.

[Cunamara]

The truth is, Maple is in abundance and in many countries considered a weed. There will be no shortages. The same for Spruce's. Exotic woods always come and go but domestic sustainable options will always be available (famous last words).

Got volunteer maples all over my yard. None of them are or will ever be suitable to make a guitar from. Sheer quantity doesn't make up for poor quality.

[Archie]

Got volunteer maples all over my yard. None of them are or will ever be suitable to make a guitar from. Sheer quantity doesn't make up for poor quality.

There's plenty of good quality maple too. Finding the figured stuff is the hard part.

[Gitterbug]

Leo Baekeland patented Bakelite, a marriage of phenolic resin and formaldehyde, in 1907. It was the first fully synthetic plastic. The rest is history and, apart from counter tops (all brands +/- 100 years), will largely remain there. For other uses, refer to Tufnol and Paxolin, for example. What were suitcases made of before molded plastic? Leather for the upper class, HPL sheet for the traveling salesmen. My first job in 1971 was with the Finnish Trade Fair Company, and the first thing I needed was a huge "fiber" suitcase that could hold up to 40 kg/90 lbs of content.

I have nothing against using HPL in luthiery and like the Richlite fretboard on my Martin acoustic. Hagstroms have used syntetic fretboards for decades. However, pressing guitars out of old newspapers soaked in phenolic resin just does not sound very futuristic vs. carbon fibre, for example. In the end, acoustic properties matter, not high temperature resistance or low electrical conductivity.

[garybaldy]

Leo Baekeland patented Bakelite, a marriage of phenolic resin and formaldehyde, in 1907. It was the first fully synthetic plastic. The rest is history and, apart from counter tops (all brands +/- 100 years), will largely remain there. For other uses, refer to Tufnol and Paxolin, for example. What were suitcases made of before molded plastic? Leather for the upper class, HPL sheet for the traveling salesmen. My first job in 1971 was with the Finnish Trade Fair Company, and the first thing I needed was a huge "fiber" suitcase that could hold up to 40 kg/90 lbs of content.

I have nothing against using HPL in luthiery and like the Richlite fretboard on my Martin acoustic. Hagstroms have used syntetic fretboards for decades. However, pressing guitars out of old newspapers soaked in phenolic resin just does not sound very futuristic vs. carbon fibre, for example. In the end, acoustic properties matter, not high temperature resistance or low electrical conductivity.

I have a couple of handmade picks made out of bakelite.

[Rickco]

There were several variations of bakelite back in the old days. Fast forward a modern version is garolite which ironically would have the opposite characteristics of the lam used for instrument's. We made assembly's with it for constrained layer enclosures because of its near 0 resonance ( kinda like a rock) pretty sure I wouldnt want a guitar made out of it. Theres a domestic product called paper stone used for counters, its all technically HPL

[Gitterbug]

Finnish HiFi speaker manufacturer Aurelia, now resurrecting under new ownership, is using HPL/HDF in their new line of high-end speakers. If routed from a single block, as some MDF enclosures are, what a waste of material!

[jaymen]

At the price point those pressure laminated guitars sell for it is probably not worth spending too much on repairing extensive breaks if they are much more problematic than repairing real wood. The stuff looks like it shatters like brittle plastic or glass, neither of which is a good thing. Thanks for educating me on the peculiarities of this new constriction material, it has helped me decide to stay away from them.

[Archie]

Don’t worry, in the long distant future, they’ll no doubt introduce you to this new wonder material called ‘wood’.

[Rickco]

At the price point those pressure laminated guitars sell for it is probably not worth spending too much on repairing extensive breaks if they are much more problematic than repairing real wood. The stuff looks like it shatters like brittle plastic or glass, neither of which is a good thing. Thanks for educating me on the peculiarities of this new constriction material, it has helped me decide to stay away from them.

Actually its very durable way more so than wood and does not shatter. Its resin with layers (usually) of substrate usually paper. The development of clear top films that are extremely tough and decorative printed materials of an endless variety make it perfect for many things. I still dont get how you use it in a guitar and really not interested. It seems to me carbon fiber would be superior although I wouldnt want that either, out of my small collection my favorite is 90yrs old, thats as high tech as I need in a guitar (and its cordless)

[Gitterbug]

While carbon fiber may be the way to go, Ovation's Lyrachord (by aeronautical engineer Charles H. Kaman; various recipes from 1996) is where to come from. Was there ever an effort to add a carved, arched top to one of those bodies?