Water based lacquer schedule?

Jim_in_PA

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I late on this - but this is exactly the type of situation where you READ the directions - and if you don't understand them call the manufacturer's tech support staff. That's what they are there for.

And unless it's a plural component or "precatalyzed" lacquer, it doesn't "cure" - it dries ONLY by evaporation. This is a big reason why thin coats are critical - and applying the entire system on scrap wood repeatedly until you get acceptable results is how you learn.

DO NOT try to learn as you apply each coat - work out all the kinks before you touch the guitar.
The shellac for sealing is certainly an evaporative finish and requires very thin coats for sure. But waterborne products, no matter what they are called, are finishes that coalesce and cure. When the word "lacquer" is on the label of a waterborne finish, such as Target's EM6000, it's because the product has been developed to have certain lacquer like properties, such as "burn in". Otherwise, it's an acrylic and it does cure, unlike solvent based lacquers.
 

Freeman Keller

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^^^^ What Jim just said is totally my understanding of water born finishes, there is a reaction, the "cure". I've tried several (not EM6000) and have come back to solvent based nitrocellulose lacquer, which is an evaporative finish. Shellac applied by French polishing is evaporative, my understanding is that many of the oils and varnishes go thru a reaction.
 

Jim_in_PA

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With waterborne finishes, "water" is not the solvent. (a reason I don't like the term "water based" because that confuses reality) Water is just the carrier. The actual cure is a chemical reaction. Yes, the water does evaporate, but that's merely because of its nature. The finish itself then does its thing on whatever it's been applied to.
 

Freeman Keller

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^^^ Again, right on the spot. Here is what LMII says about KTM-9 (which they were selling in 2017 but have discontinued).

KTM-9 is a self-cross-linking urethane/acrylic co-polymer which cures to hard in one week.

Several builders who I greatly admire were using it at that time, as I did on a couple of guitars. There were some issues so I went back to nitro. This guitar was finished with KTM-9 with Zpoxy as a pore filller

IMG_0023.JPG
 

Silverface

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But waterborne products, no matter what they are called, are finishes that coalesce and cure.
Respectfully, this statement is incorrect.
Otherwise, it's an acrylic and it does cure, unlike solvent based lacquers.
I spent 40 years in the coatings business - most in the technical support, site inspection, specification consulting and failure analysis end; 7 years as vice president of a contracting firm supervising 20 to 100-man crews that applied everything from conventional paints to lacquers to 1" thick, robotically-applied pipeline coatings. And over 30 or those years included teaching both technical and application courses in coatings types and formulation and practical application techniques.

Many on this forum get confused about the terms acrylic, nitro, solvent, dry, cure etc - so here's some basic coatings technology:

"Acrylic" is not directly related to the word "cure", nor does it mean "waterbased".

"Acrylic" is a generic term that only defines a huge range of resins. Resins are raw materials manufactured by companies such as Dupont, Rohm and Haas, Sherwin Williams and dozens of others. Other common resin types are "vinyl", "polyester", "polyurethane" etc.

In any type of coating, the "resin" (or more commonly, blend of resins) is/are the single largest "solid" - the material left on (or in) the surface

Acrylic resins are used in typical house paints (anything from flat to high gloss), some in industrial paints (with the same wide range of gloss types), some in flexible plastics, some in hard plastics....

...and some in "lacquers".

With complete respect to our knowledgable friend @Jim_in_PA, the terminology used is incorrect:

"Solvent" is one of the THREE major components in a "conventional" coating (and most catalyzed coatings). As much as @Jim_in_PA may dislike the term "water born", another term for "solvent" is "carrier". Lacquer thinner is a "carrier" and a blend of "solvents". Water is also a "solvent".
But for simplicity, we'll just use the terms "water based" and "solvent based" - with "solvent" meaning "flammable".Water based and waterborne are interchangeable terms in the context of commonly available wood finishes.
"Pigment" is the second - and pigments can be clear (when used as fillers or for other purposes)
"Resin" is the third.

There are two common types of lacquers:

1. "Conventional" lacquers (where acrylic resins are used alone and often in blends with cellulose nitrate resin - aka "nitrocellulose or "nitro"" resins - or nitrocellulose resin alone) - both in solvent and waterbased types .

These types dry ONLY by evaporation of the volatile components - carrier (solvents and/or water), surfactants (flow agents - basically "soaps" that break surface tension, smoothing the surface of finish coatings and assisting penetration into the substrate -such as sanding sealers and lacquer primers that penetrate into wood), defoamers and other specialty chemicals that function only during the application and evaporative time.

"Curing" is a chemical reaction- and no chemical reaction takes place for conventional lacquers to dry - ONLY the evaporation process. And they ALL contain evaporative components.

CONVENTIONAL SOLVENT AND WATERBASED/WATERBORNE LACQUERS DO NOT CURE. EVER. BUT keep reading -

And the second most common type of lacquer:

2. "Plural component" (and "precatalyzed") lacquers.

In our context these both "dry" AND "cure". We'll eliminate one type of plural component lacquer from discussion as they are "100% solids lacquers"(i.e. they contain NO evaporative materials). These are available ONLY to industrial applicators and require specialized application equipment.

And "precatalyzed" lacquers require a reaction with oxygen before they begin to dry. They almost always contain evaporative materials and must dry by evaporation, but also react with oxygen in order to fully harden (a "curing" process). They are available in formulas containing nitrocellulose, acrylic and various blended resins. And they may contain water, solvents or a blend as carriers.

Plural component lacquers are packaged in two containers, and must be mixed for the "curing" process to take place. They usually contain carriers and other evaporatives that must evaporate - so they also "dry".

But the chemical reaction ("curing") is the primary difference between these and "conventional" lacquers.

"Plural component" and "precatalyzed" lacquers may contain acrylic, nitrocellulose or both resins and may be "waterbased", "waterborne" ( As I indicated earlier those two terms are technically different but the same in this context) or use flammable solvents as carriers.

So - in very basic terms these are the only two things to remember:

"Plural component" and "precatalyzed" lacquers MUST "cure" and usually dry by evaporation as well. They may contain acrylic, nitrocellulose or both resins and be waterbased or flammable.

"Conventional lacquers" DON'T "cure" and ONLY dry by evaporation.They may contain acrylic, nitrocellulose or both resins and be waterbased or flammable.

An acrylic lacquer does not cure unless it requires a catalyst. The carrier type - water and/or solvent - is irrelvant. But the catalyst CAN be oxygen. And this where "Read the directions" is critical, as SOME acrylic lacquers contain additional polymers that "kick" off a curing process. MOST do not.

Nor does a nitrocellulose lacquer cure UNLESS it requires a catalyst.


PLEASE note that the coating @Jim_in_PA uses as a technical reference is not available in most of the US - it is an example of a less-common type of waterbased lacquer - Target (not the Target department stores- it's a coatings company in this case) even sells a catalyst for it to improve resistance to cleaners and specific chemicals.

And the bold section above is the single most common misconception among DIY, amateur and self-taught "professional applicators". It's critical that you know what you are using - and especially if it's a less common coating.

"Acrylic" does not mean "cures", nor does it mean "waterbased" - it simply means the primary resin type.
 
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Jim_in_PA

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"Acrylic" does not mean "cures", nor does it mean "waterbased" - it simply means the primary resin type.
To be clear, I made neither assertion in my previous post. My point was most waterborne products use acrylic resins (I did leave out the R-word) and they pretty much all do cure. Sorry I was not as specific as I should have been.
 

Silverface

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My point was most waterborne products use acrylic resins (I did leave out the R-word) and they pretty much all do cure.
I thought what you said was pretty specific - But the problem is the pretty much all DON'T cure.

The product you are using is unique type of acrylic lacquer using a copolymer not common to most acrylic lacquers, and a product with limited availability.

My point was that the vast majority of acrylic lacquers used by folks in this forum are conventional solvent-based acrylic lacquers. But whether solvent-base or water-base, the vast majority dry only by evaporation.

A single coat of properly-applied conventional acrylic lacquer - whether solvent OR water base - dries only by evaporation of the volatile components. Most dry in 30-60 minutes per coat (a few recommend 2 hours for the final coat). Once the volatile contents have evaporated it's dry - and there's no cure time.

We apply 8-10 coats of acrylic, nitrocellulose, or both lacquers over 2-3 days; buff it out the last day - and either assemble parts or hand finished parts to the customer 4-5 days after starting, unless filler or oil stain work is required.

THERE IS NO CURE TIME. Some manufacturers mistakenly use the word "cure" instead of "dry" on their data sheets, but unless it's a product intended to crosslink, it can't "cure".

A few examples of brands used by folks on this forum are the acrylic lacquers made by Rust-Oleum (solvent base), Mohawk (both solvent and water base) and Duplicolor (solvent base). All dry only by evaporation (Mohawk makes water base precatalyzed and post-catalyzed, the latter similar to several Target coatings.

But only "precatalyzed", "post-catalyzed lacquers" and lacquers made with unique "copolymers" (a blend of specialized acrylic resins) "cure". The MUST be a chemical reaction for "curing" to take place.

And no chemical reaction occurs with the majority of acrylic (and solvent) base lacquers.

I think where things are getting confused is that you are using a unique type of product neither used nor available to most of the U.S. and mistakenly think it's typical of most of the acrylic lacquers. It's not.
 

Jim_in_PA

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Again, I was not referring to any solvent-based product. This discussion is about waterborne/water based finish. Target Coatings products are made in northern New Jersey and shipped anywhere within the continental US and likely beyond. That's a fact

No matter. I'm out of the conversation. :)
 

Silverface

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But waterborne products, no matter what they are called, are finishes that coalesce and cure. When the word "lacquer" is on the label of a waterborne finish, such as Target's EM6000, it's because the product has been developed to have certain lacquer like properties, such as "burn in". Otherwise, it's an acrylic and it does cure, unlike solvent based lacquers.

This discussion is about waterborne/water based finish
Jim, I wasn't trying to be argumentative - just factual when it comes to waterborne lacquers (and I only included solvent-based lacquers to AVOID confusion).

The issue is you are making factual statements using all-encompassing terms ("it's an acrylic and does cure, unlike solvent based lacquers").

That statement may apply to a specific product - but these threads pop up in Google searches, especially when inexperienced applicators are looking for information.

The problem being the individual post shows up - but not the entire thread. This has been mentioned several times on the forum - if discussing a specific products characteristics it's important to mention that product in the post.

And while some may buy lacquers by mail order, others don't like the shipping costs or lack of local tech support and buy locally available products. Most of the US has never heard of Target/Emtech unless it came up on the internet.
 

azureglo

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If this is what you're trying to achieve, I am doing something identical using cellulose sanding sealer/water poly clear varnish:


Satin
l
52249072324_f919520f0f_b.jpg

Gloss
52249072159_cccf30afa3_b.jpg

52249287080_2c7d4cd76c_b.jpg


Details here: Hardtail
 




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