Glazing Pigmented CV and Sanding Questions

      Glazing with conversion varnish can be tricky. Here, finishers discuss some fine points. October 15, 2009

I just finished my CV on all carcasses and frames, assembled and installed. I'm moving on to my doors and trim, which now need glaze.

The schedule before was as follows:
150 sand
SW cat vinyl sealer
150 sand
SW Kemvar primer surfacer
150 sand (transparency was brought back and most product was sanded off; mostly used as a slight grain fill and leveler)
SW pigmented CV
180 scuff
2nd coat SW pigmented CV
320 scuff
1 coat clear Kemvar WW CV

The results are great and from what I've seen, the dft is under 5 mils on frames where there were a lot of overlapping passes. Now I need to add a glaze coat in on the next few runs of finishing. I really don't want to glaze over the white, as I've heard it stains (going to test tomorrow), but that would add another coat. Anybody put a Kemvar glaze on their pigmented CV? The reps have all told me that there is no need to sandwich the newer Kemvar glaze with vinyl.

Some will say the sanding is too fine, but the tech sheet for the primer says 400-600 to keep scratches down. I've stuck with 320 max, but I get burn-throughs on the edges. What do you guys use on your routed edges that need to be sanded for glaze? I've tried the red scotchbrites with a few burn-throughs, and I think the greys are a little too fine. The SW reps keep telling me that if I just knock the gloss out, I've opened the pores and I sanded enough. One even said that he just finished his personal kitchen and didn't sand between the three final coats. He said that the product will chemically adhere as long as the recoat window is maintained.

All of my work from first sand to last coat is being done in an 8 hour day. Temps are right around 70-72 degrees and the finished items are kept in a temp controlled room for at least a 72 hour initial cure (they won't see less that 65 probably ever). Any opinions?

Forum Responses
(Finishing Forum)
From contributor J:
I've always found glazing and CV to be a bit problematic at best, and try to stick with pre-cats when glazing if I can. The trouble comes with the recoating of the CV after glazing. If you don't scuff the previous coat of CV well enough, adhesion is a problem. If you do scuff well enough that you don't have to worry about adhesion, then the glaze wants to take into the sanding scratches. If you rush the glaze while the base coat of CV is still green, then the glaze bites into it and changes the color.

I found that using an uncatalyzed vinyl sealer before glazing helps even when the glaze does not call for a vinyl sealer. The CV ends up getting some solvent bite through the glaze and into the vinyl. Just out of curiosity, what is the purpose of the vinyl sealer under the primer surfacer in your schedule? I put primers, surfacers straight to the wood under opaque finishes.

Other than that your schedule looks fine. The 180 scuff of the first CV coat is rougher than what I would I use, but if it works for you, great. Oh, and I would be very cautious of overall mil thickness too.

From the original questioner:
Thanks for the reply. I only use the vinyl under the primer for the 5 piece doors with the MDF centers. I'm thinking that the only way to do it and get good results would be to put on my pigment, one coat of clear, glaze and then another coat of clear. That way the glaze won't bite into the white. The Kemvar glaze is meant to be applied to CV without sanding, but there still needs to be a scuff between coats. Since I'm only doing a hanging glaze, I'm hoping that my scuff after the glaze will help to remove the stubborn glaze from spots I don't want it, plus help the next coat of CV to adhere.

From contributor J:
That sounds a lot like the way I do it. I use a pre-cat vinyl base coat from Valspar with the color mixed in as my primer. This cuts the primer/color steps in half. Scuff sand the first coat, then shoot a second color coat and then clear before glazing. One less product gives me less mil thickness to worry about, so I can scuff the first coat of clear over the glaze and shoot the final topcoat really smooth.

From the original questioner:
I just have issues with burn-throughs with my sanding. They aren't all the way to bare wood, but they actually make the spot darker. They almost look like black greasy fingerprints. With dyes and stains, the grain pattern hides this. With pigment, it's a no go. Why do you clear before glaze? I like the idea and think it will work better, but I'd like to hear your reasoning.

SW has said that 4 mils is a guideline and that one of their larger production shops (in So Cal area) won't go below 8 mils on their pigmented jobs. My dft has been between 3.5 and 4.5 on my non-glazed items.

From contributor J:
The reason I clear before glazing is the vinyl base coat I use is actually a tinted primer. Being pretty much dead flat it will soak up glaze like a sponge and drastically change the background color. So on jobs where the customer wants the clean, "glaze only in the profiles" look, it makes it a lot easier to clean up excess glaze off the surrounding surface if you put down a coat of clear first. On other jobs where I am looking for a very heavy glaze effect such as faux finishes, I glaze directly over the vinyl color coat.

As to your problem with sanding spots, I have had the same issue and found the best way to avoid it is not to sand my second color coat or the clear coat before glazing, which is why I like to stick with uncatalyzed vinyl and pre-cats for the solvent bite. Post-cats would have some definite adhesion issues with this method.

From contributor O:
What type of sandpaper are you using? This can make a difference. I'm glazing over two coats of CV which I sand, then a clear which I don't sand. Topcoat with CV within the re-coat window. I'm using a solvent to slow it done and get a smoother finish so there's less sanding. I'm in SoCal - are you?

From contributor U:
I see you are a SW user, but that seems like an awful lot of steps to achieve such a simple look. I'm a Campbell user, and to replicate what you are doing my steps would be as follows:

1) Sand all panels with 180, or no finer than 220.

2) Apply a coat at 5 wet mils of their post-catalyzed Clawlock primer. This is a very high solids primer and sands like a dream. It can also be tinted to any color so this satisfies the color issue as well. Give it an hour to dry, then sand with 320 foam backed paper. Apply another coat of your tinted primer, same mils and application procedure.

3) After an hour dry time, sand the primer with 320 grit foam backed sanding paper. This is where good technique pays because you don't want any burn through.

4) If you typically use a wiping glaze, they offer the Vintage Alkyd Base wiping glaze. It does not require sandwiching between vinyl coats. Some in the industry call this product simply "no vinyl glaze." It does require about an hour for dry time, but it is very workable, and is great for antique looks. If application and dry time is an issue, try Campbell's Amazing Glaze. It is spray only and very acidic as far as biting into anything less durable than Magnamax (cured at least 12 hrs) or any of their post-cats (only 1 hour dry time necessary). Once applied, this stuff dries in seconds, and works off where you don't want it with a scotch-brite pad. CATech offers a glazing tip (looks a lot like a basketball pump needle) that replaces the tip on the gun, and allows the glaze to flow into the details and only in the areas you want it. Again, you get a very fast application, as well as dry time.

5) Apply a clear topcoat (would recommend at least Magnamax but prefer Krystal post-cat over top). Sprayed at the right mils (4-5 wet), one coat of clear on top is enough, but two coats is superior.

Using these products, you can achieve a very durable, very nice looking, and very fast project. The pricing up front might be a little higher for materials, but your labor will be reduced with less steps and less down time waiting on paint to dry.

Would you like to add information to this article?
Interested in writing or submitting an article?
Have a question about this article?

Have you reviewed the related Knowledge Base areas below?
  • KnowledgeBase: Knowledge Base

  • KnowledgeBase: Finishing

  • KnowledgeBase: Finishing: General Wood Finishing

    Would you like to add information to this article? ... Click Here

    If you have a question regarding a Knowledge Base article, your best chance at uncovering an answer is to search the entire Knowledge Base for related articles or to post your question at the appropriate WOODWEB Forum. Before posting your message, be sure to
    review our Forum Guidelines.

    Questions entered in the Knowledge Base Article comment form will not generate responses! A list of WOODWEB Forums can be found at WOODWEB's Site Map.

    When you post your question at the Forum, be sure to include references to the Knowledge Base article that inspired your question. The more information you provide with your question, the better your chances are of receiving responses.

    Return to beginning of article.

    Refer a Friend || Read This Important Information || Site Map || Privacy Policy || Site User Agreement

    Letters, questions or comments? E-Mail us and let us know what you think. Be sure to review our Frequently Asked Questions page.

    Contact us to discuss advertising or to report problems with this site.

    To report a problem, send an e-mail to our Webmaster

    Copyright © 1996-2016 - WOODWEB ® Inc.
    All rights reserved. No part of this publication may be reproduced in any manner without permission of the Editor.
    Review WOODWEB's Copyright Policy.

    The editors, writers, and staff at WOODWEB try to promote safe practices. What is safe for one woodworker under certain conditions may not be safe for others in different circumstances. Readers should undertake the use of materials and methods discussed at WOODWEB after considerate evaluation, and at their own risk.

    WOODWEB, Inc.
    335 Bedell Road
    Montrose, PA 18801

    Contact WOODWEB

  • WOODWEB - the leading resource for professional woodworkers

      Home » Knowledge Base » Knowledge Base Article