Nitro problem -- need help!

[Harold in Tn]

This is a problem I am having with finishing. The finish is Behlen's lacquer.

[ken cierp]

This is what I suspect

http://www.woodfinishsupply.com/LacquerRetarder.html


Behlens has a good technical support team it would not hurt to contact them -- send along a picture as well. Other then the blush that guitar looks real nice.

[dhlutherie]

I agree with Ken's assessment and the link provides some excellent advice. Blushing is an extremely common problem when applying Nitro Lacquer. Because I have to spray in my garage I will regularly encounter this problem during the summer months. Any time that the humidity is > 70% (approximately) you will definitely encounter this situation. Regardless of your repair at hand I would purchase some retarder so that you always have it on hand. Here are some additional comments:

1. If the "blush" has not been coated over you can always sand off the previous coat. If you are not spraying your finish this is probably the only approach (see comment below on Blush Remover).

2. As suggested in the subject link, you can mix up some lacquer reducer (thinner) and retarder and spray a coat over the affected area. It may be wise to spray complete sections as the "blushing" can sometimes be hard to see until later. Dial down the spray gun (fluid amount), move the gun back, or move quickly to not flood the area. The trick is to apply enough thinner/reducer, but not apply so much to create runs. DO NOT APPLY WITH A BRUSH YOU WILL END UP WITH A HUGE MESS! If you don't have a spray system purchase a rattle can of Blush Remover.

3. If the blushing is minimal your next coat (with retarder added) may eliminate the blush. If in doubt sand the previous coat with a fine grit (320 or greater) abrasive.

4. When adding retarder make sure to follow the manufacturers recommendations. Do not use too much retarder as this can create problems with the finish. Too much retarder, at minimum can dramatically extend drying and curing time. It can also leave the finish softer than normal.

5. If at all possible use the same manufacturer for both the lacquer, lacquer reducer/thinner, and retarder. I have had some "interesting" reactions between some lacquer thinners and lacquers. If in doubt mix up a small amount in a clear glass jar to assess compatibility. Once you find an acceptable match between a thinner and lacquer stay with it.


If you are going to be doing a lot of finishing I would recommend that the following authors/resources - Michael Dresdner (spelling?), Bob Flexner, or Jeff Jewitt.

[Harold in Tn]

Thanks for the info. Let me see if I ubderstand this. Since I have sprayed all the lacquer that I want to and have polished the surface, then I should get a can of Blush Remover, spray it on as a "mist coat" and then what? Let it sit, rub it in or what? Thanks again for the help.

[Harold in Tn]

Probably follow the directions on the can, right?

[dhlutherie]

If the blush is trapped below additional coats of lacquer I'm not sure that the blush erase will work. You will have to test it and see. DEFINITELY DO NOT WIPE THE BLUSH ERASER AFTER APPLICATION. I believe that this product is a combination of lacquer reducer and retarder. As with all solvent type lacquer products each coat will soften or melt into the previous coat. Wiping the spot will create a huge mess! While I have not used this product I assume that the instructions will tell you to apply a wet spray coat and let it sit and naturally dry.

In the event that the Blush Eraser does not work you will have to sand the affected area to get close to the problem. Either your sanding will remove the defect or it will allow for the Blush Erase to do it's thing. Don't agressively sand the area or you will create additional problems. Feather your sanding out from the area. The best approach is to use either 400 or 600 wet sanding paper. You will probably have to apply some light coats of finish to the affected area, again feathering out the finish. Let the repair sit for at least 4-5 days (minimum) before attempting to again wet sand, rub-out, and polish. The key is to take your time and error on the conservative side. Pushing the repair can create additional problems and a lot more work.

[Harold in Tn]

Dave, I don't know if the picture came through or not, but I tried the blush eraser to no avail. If the picture is here, then you can see that I have sanded down to the wood in that one spot. Ken's advice is to sand the entire top down to the wood and refinish. I can do that if I have to. What do you think??
Harold