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Has anyone used the CL100 Cross-Linker? If so, what was your experience with it? Is it either beneficial, not necessary, or detrimental to guitar finish?

EM6000 Production Lacquer can be fortified with our CL100
Cross-Linker to create a post-catalyzed type lacquer. The addition
of 5 to10% by liquid volume of CL100 will improve the physical durability
of EM6000 by tightening the molecular structure
of the cured resin. CL100 improves the resistance of the cured
film against high pH cleaners, alcohols and slow evaporating
household chemicals.

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

I haven't tried it, but I'm interested to hear if anyone has. I would like to know if it affects the "burn in" and/or reparablility characteristics of EM6000.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Jay - Speaking of burn-in and repairability… I wet sanded through a very small spot on the back of my headstock of my latest and thought I could spray the end of the headstock to make a repair. After spraying 5 coasts, I let it cure for 6 days (120 hours is the manufacturer's cure time). Upon wet sanding and buffing I got witness lines. I didn't expect that because EM6000 is supposed to be so easy to repair (100% burn-in). Now I have to go back and spray the entire back of the headstock and wait another week before I can buff it out. I guess lesson learned is if you have to make a repair you better respray the entire surface (section) so you don't get witness lines...

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

That's a bummer. Do the witness lines correspond to the original edges of the sand through or do they correspond to the edge(s) of the new spray coats (assuming the new coats extend beyond the sand through area)?

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

...the edge of the new spray coats...

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

Generally speaking the addition of a crosslinker to a coating will cause the coating to be harder, denser and breathe less. Think of the coating at the molecular level as a box of baseballs. Adding a cross linker is like adding ping pong balls, it fills in vacant space between molecules and locks them together tighter than they would link otherwise.

These additives usually speed up dry times as well by taking up space that solvent (water in this case) would occupy and as such your open re-coat times typically get much shorter. EM6000 being a poly type coating there is no burn in between coats with or without crosslinker once it has passed the open re-coat window timing.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Thanks Brian.

You said, "...re-coat times typically get much shorter". Is that a good thing? Does that mean that you could shorten the time between coasts, say, maybe 20 minutes? And, would that mean that total cure time (120 hours) could be reduced? Also, "...there is no burn in between coats with or without crosslinker...". Does that mean that Target Coatings' claim of 100% burn and easy repair not exactly accurate?

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

Open re-coat times.... so that 24 hours maximum may become 6. Time to re-coat is different and based on evaporation and that may not change.

From the em6000 TDS.... " identical to those of traditional nitro-cellulose lacquers and CAB acrylic systems."

Those two systems behave very differently as I have run a lot of both over the years. So this is false in some sense....

" Sanding between each coat is not necessary unless contamination has effected the film formation, or if the last coat has dried for more then 24 hours."

If you must sand after 24 hours..... there is no "burn in like a traditional nitro.

"Complete chemical cure time is after 120 hours within these temperature ranges"

Kinda says it all.... And the fact they make no mention of repair procedures after making the just as easy to repair claim is the last nail in the coffin. Learn to read a TDS and ignore the marketing hype BS.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

I don't know what can be dismissed as just marketing claims, but I do know that I've repaired a number of sand throughs, dings, and chip outs without ever getting witness lines. Some of these repairs were done while applying the original finish to the guitar, others were a year or more after the original finish was applied. The repairs blended in just fine. Whether it burns in the same manner as nitro or not hasn't been an issue for me.

Steve - This is not at all meant to discount the problem you're currently fixing. I don't know why there were witness lines after spot spraying. I would guess it would come down to some difference in the methods used or conditions.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

CA leaves no witness lines most times on any finish. Witness lines in poly type coatings come down to one thing.... mechanical interface or how much tooth is required to blend it out.

Lack of witness lines is not proof of chemical bonding. Nitros work as much if not more on chemical bonds while poly is purely mechanical. Witness lines between coats of poly are very dependent on prep with coarser sanding typically providing less witness lines.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

I would love to try poly if I could assure myself of no witness lines. I love the look and scratch resistance and no explosions to worry about.

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Hutch

Get the heck off the couch and go build a guitar!!!!

I don't know why I got witness lines... I had a sand through during wet sanding at the corner of the back of the headstock. So, the finish had cured for almost 3 weeks. I sprayed several coats on the upper half of the headstock and waited a week before wet sanding. I don't have any pictures, but I got a witness line at the transition between the older and newer finish. I continued to try to sand out the line. I kept sanding and couldn't get past the line. I finely had to take off the finish and spray again.

I wonder if there was a humidity component... Rather then set up my spray booth I simply stepped outside (while it was raining under a covered porch), quickly sprayed and brought it back inside. No cloudiness formed and it cured for over the 120 hours the manufacturer recommends, in my humidity controlled house. Seems like if the finish was allowed to cure (that is, all of the solvent, in this case water, was allowed to dissipate, then the finish should burn into the previous finish. Maybe I need to be more cautious with humidity... or is that's not the issue?

This is the first time I have seen this. I have used EM6000 for over 10 guitars. I like the product and find it is generally quite forgiving.

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

Thanks for that point, but just to avoid any potential confusion in this discussion, the repairs I was talking about above weren't done using CA. They were EM6000 on EM6000.

The problem I've had when I tried CA repairs was leveling the CA to match the surface contour of the surrounding finish (particularly on tops). I suspect that was due to the difference in hardness between the CA and the finish. I know the tricks of initial leveling with a taped razor blade and using a very narrow strip of sandpaper and pulling it across the CA fill so as to not sand down the surrounding surface, but I couldn't get a completely invisible repair. They looked fine when viewed straight on (no witness lines), but when viewed under reflected light, there was a glitch in the reflection at the position of the repair. With EM6000 on EM6000, I've been able to avoid that problem. Maybe with practice, modified technique, or using a different CA, I could make it work.

Back to something along the lines of the original question, would using the cross linker make witness lines more likely?

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Oh? Hmmm maybe that is why I always got white lines on water base repairs, I always sanded it through 1500 or more thinking that the smoother the transition the less likely to show. So is it that the coarser transition provides some sort of refraction of light or something?

I USED to use EM6000 (been a few years)...

I tried the cross linker a couple of times. I didn't like it. I had trouble mixing it- leaving clumps of different density finish. I got one good mix and didn't notice much of an improvement to the durability of the finish (on a test panel). Maybe things are different now, but that was my experience back then.

As for touch ups and witness lines, EM6000 works via chemical bond not mechanical bond. Jeff from Target suggests wiping the surface with a 50/50 cut of denatured alcohol and water to prep the surface for touch up. This softens the finish and preps it for chemical adherence to the new coats. Even still, I would notice witness lines... but they'd often disappear during buffing (with a little heat). On the other hand, I always saw witness lines with CA touch ups on EM6000.

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