Hello

I would normaly ask this question to the manufacturer (mohawk here) but they seem to take forever to reply and their answers seems to be vague and sometime doubtfull. The only infos they provide seems to be about nitrocellulose lacquer without specifying if catalyzed or note.

So I want to make a black toner. I have a vinyl sealer and POST-cat lacquer (One you have to catalyse the whole gallon). Mohawk have proposed me to glaze between lacquer coats but from my experience with lacquer you use toner since the burn in process can cause problem. I suppose I could glaze between vinyl coats but want to try to keep the sealer coats to a minium.

How do you guy do it? (I mean technique not the receipe) If possible I would prefer using my black mixol paste since it is "blacker" and my transtint dye give more of a dark blue/black.

Tone using vinyl sealer?

Tone the catalyzed lacquer? I Read here that you should not tint finish with acid catalysis.

How do you handle sanding? these coats are so thin (I keep them Under 3% solid) yet all spec sheets recommand sanding with 320 between coats.

Right now I have tested both ways without sanding the toner coat (juste applied one) and got similar results in apperance. The only Odd effect is when I apply a heavily reduced post-cat coat it dry with a completely MATTE (and I mean NO SHEEN at all) appearence. The seen is restored when I Apply the next clear coat.

After nail scratching both pieces after 48h I seem to have no intercoat adhesion problems. If I scratch hard enough to remove the finish the coat come in one "piece" and doest seems to flake.

Thanks for your help.

I don't know if I'm understanding correctly
Are you trying to get a "glaze" effect?
Is it a stain job?
If you are using a post-cat top coat, you need to stick with the system
Post cat sealer and use a glaze that is compatible with the system
When glazing, adhesion is compromise so you need to be careful and know about what product to use

My Schedule goes like this

-Dye (bare wood)
-Washcoat (3% vinyl)
-Pigment stain
-vinyl TONER?!?!
-Vinyl sealer
-Grain filler
-post cat TONER?!?
-Topcoats

Now like I said I have tried tinting the vinyl sealer and the top coats using mixol paste with good results. From what I have read when you use a lacquer system you use toners since lacquer need to burn-in the previous coat and glaze could cause problem.

My main concern is the fact that most infos I could find speaks about straight lacquer. You put mixol in them, spray thin coat and dont worry about adhesion since they burn in regardless of the drying time.

With postcat I found little infos (and mohawk was very vague about how to do it). I am not necessarily looking for mix receipies but rather exprience regarding what to tone (the sealer? the post cat?), to sand or not that coat and wich products people used (I got mixol paste here).

Right now I have had sucess tinting both the vinyl sealer and the post cat and skipping the sanding on these coats. The resistance seemed about the same with all three samples (untoned, vinyl toner, postcat toner). And like I said the only odd effet I got was when spraying the lacquer toner was that a coat that had NO SHEEN at all (completely MATTE) but it was restored after the last coat.

I know I won't get definitive awnser but rather idea to try and experiment to see wich seems to work best. Most infos I found is about regular lacquer and/or it was unclear whether the expert was refering to regular/catalyzed lacquer

Normally I do a self seal with a post cat. So I would first stain if needed and then put on a seal coat. Then I'd mix up my toner/shader coat with the catalyzed mix.
Usually I thin this 50%.

I'll scuff with a Mirka Mirlon pad to get a toothed surface and apply the toner.

I spray it on with an HVLP to control the color depth I want. And with black you need to wait about 10 minutes for the color to completely form. I find it gets darker in that time.

Then I spray on as many coats as needed to get the color I want and wait for it to dry for sanding. Scuff lightly and topcoat.

I'm using a ML Campbell Microton Dye for my color. And it too has a blue tint to the black. Usually when doing this I'm doing transparent black so I'll stain with a pigmented black stain which seems to deal with the blue tint of the toner.

thanks for your answer leo.

Generally what gritt do you use when scuff sanding a toner coat. My main concern (other than sanding throught the finish) would be to end up with an uneven toning coat by an uneven sanding.

My post cat recommend a 320 gritt between coats.

Thanks

I pretty much do all my scuffing at 320. The Mirlon pad is 320, maroon colored pad.

I'm not really scuffing as much as toothing. Not worried about leveling, just getting a scratch in there. Since I'm working on the toning I just keep going around in circles until I get the desired color on all pcs. I don't scuff between tone coats as long as they are within about 2 hours.

thanks leo so if I understand correctly your are describing something like

lacquer
scuff sand
toner as needed
no sand
lacquer

as long as I dont let the catalysez toner harden too much the clear coat should "bite" into it? my lacquer specify a minimum drying time but no max recoat interval.

I myself would likely scuff the last coat of the toner before the last one or two coats went on. I just wouldn't want to chance a problem later on. Again, just a light scuff with the Mirlon pad would be enough.

thanks a lot leo will get some of those pads and test the schedule on scrap

You'll really learn to love them. Another one to love is the foam back Mirka Soft Gold. Especially if you are doing contoured surfaces..

I sound like a salesman. :o

Here is a general priciple for vinyl sealer, scuff it first. In general this applies, but not always.

Sanding:
1. To create a tooth to the finish, a scratch pattern. Or...
2. To level, to cut down, to contour, to shape, to "get rid of."

Scuffing: when you only need a tooth, only need to roughen the surface, you only need a scratch pattern in your surface.

To scuff, for sure the red Mirka "scotchbrite" creates a great tooth. It's a more flexible pad then the 3M Scotch-Brite pads. In terms of tooth, both 3M Scotch-Brite & Mirka are generically called "non-woven abrasive pads. To scuff in between coats in order to have a scratch pattern, Mirka or Scoth-Brite red or gray non-woven abrasive pads will scratch enough for your next coat to achieve proper intercoat adhesion. Steelwool will, also. In sandpapers you can use up to at least 600 grit. As a general practice, 320 is the norm and finer sanding might be too fine. You could do 220 but then your sand scratches will show.

When sandwiching glaze, if you scuff the undercoat, versus not scuffing, then the look of the glazecoat is different. Not scuffing the undercoat gives you a cleaner wipe. Scuffing gives you a dirtier wipe. It's a matter of looks & anesthetics how clean or dirty to wipe.

When possible, scuff, at very least. A mechanical bond always enhances the performance of your finish system because you don't want to just assume that your coat bit into (burned into) the undercoat enough. Even with NC lacquer on NC lacquer, I've experienced witness lines when I've accidentally sanded between coats, even though one would think that the coat should've melted into the undercoat. Whoops.

You can add Mixol to your catalyzed topcoat. It's best to "let it down" in lacquer thinner and then add the colored lacquer thinner to your catalyzed lacquer.

Your washcoats can be anywhere from 3% - 6% solids, I also like to keep my washcoat at 3%.

The advantage of using vinyl sealer versus self-sealing is that vinyl sealer penetrates into the wood or MDF better than your topcoat, and it's this extra penetration of the sealer into your substrate that gives your final more resistance to moisture. For me, I prefer the added resistance to moisture. I also prefer toning with vinyl sealer versus topcoat because the vinyl sealer is usually thinner than whatever topcoat material that I'm using. Last, the sealer coat shouldn't be more than 1/2 dry mil of your total finish system unless your using a sealer that, by design, you can build to much more than that 1/2 mil, e.g., ML Campbell's Level Sealer, polyester sealers, plural component polyurethane sealer.

thanks a lot dan for that indepth answer.
so basically toning the sealer or the topcoat seems to be a matter of preference since I havent been able to find a definitive answer.

I will also try to scuff LIGHTLY my toner coats to avoid adhesion problem. I also did the samething after my stain and let me tell you it was more like stroking the stain with the sandpaper rather than sanding.

I tested the sanding pressure on scrap pieces for the stain and it man it was a light pressure. As soon as I started to scuff the stain would come off.

I will do the same thing with my toner to gauge the pressure I can apply.

I think as scuff sanding as getting rid of the gloss. Not so much you need tooth. The gloss surface could be 2000 grit(???) You need to get it much lower. The efficient way is to use the most aggressive grit possible. As others have noted 240 grit scratches are visible in both clear & pigmented coatings. Therefore 320 grit is the proper choice. In theory you could sand 600grit, as long as you get rid of the super smooth gloss. It would take longer and use more abrasive.

Scotchbrite type pads are great because they don’t clog.

The reason for scuff sanding is because the bond is often more mechanical than chemical in later coats, sometimes *only mechanical*
(depends on exact finish type, of course).

So how hard/much you need to scratch it depends on the finish type involved (and often it's exact formulation).

It does not carry over magically to any other finish, either, and unless you know enough about the chemistry, you aren't gonna guess well :)

If you want to know whether whatever you do for scuffing is sufficient, do a cross-hatch test with a box cutter and a piece of tape.

That is what will tell you whether what you want to do is sufficient or not.

Everything else is just a guess or a guideline, and won't give you a real answer while that simple test will.

Daniel,
Could you describe the cross hatch test in more detail? Do you cut at 90º and try to peal back with tape? What kind of tape please?

Easiest way:
https://www.amazon.com/CGOLDENWALL-Adhesion-Cross-Cut-Multi-blade-spacing/dp/B0751
4H9CK/ref=dp_ob_title_kitchen

Contains all you need and directions.

If you are too lazy, and even that is not cheap enough, a box cutter/exacto knife and regular masking tape works fine.

If you want the exact right tape, it's https://semicro.org/products/cross-hatch-testing-tape-1x60-yd

or https://www.elcometer.com/en/elcometer-99-cross-hatch-coating-adhesion-test-astm-t
ape.html

Truthfully, for the situations being described here, this level of exact testing tape is not going to be needed.
Most finishes that are well adhered are not going to be pulled off by most masking tapes you have laying around.
Most finishes that are not well adhered will be ripped off by *any* tape you have laying around.

While it is possible to end up in the middle, it's somewhat rare unless you are hand scuffing and inconsistent, or the finish is curing unevenly.