Replies

1. 
   Sgian_Dubh | Jul 22, 2001 03:50pm | #1

   *
   This is a nitrocellulose lacquer from ML Campbell. I use ML Campbell products quite a bit, and you're coming up against the 'finish printing' factor, which is what you described. I'm not sure from your description how long you are leaving the first side to dry before flipping over and spraying the other side. I allow overnight at least, and 24 hrs. is better, and this varies with the temperature you are working in, 70°F being the median generally used for calculating such factors. Using your method you can end up with a roughness due to overspray on the first side polished unless you mask off carefully to the edge.

   I also use alternative methods, e.g., I'll drive 3 pins into the hidden or less visible side of the panel, perhaps into the tongue if it's a panel held in a frame, spray this pinned side, flip over immediately, spray the show side, rub down lightly ten- fifteen minutes later and leave it alone at least overnight, or even better, for 24 hrs before I recoat. With pre-cat lacquer, three coats is about your limit before you increase the chances of chinese writing occurring, but with the nitrocellulose you are using you can build up layer upon layer.

   Also contact your supplier or ML Campbell directly. They have a lot of printed technical information they can, and will happily supply you with. ML Campbell I have found like happy customers and they go out of their way to help. Sliante, RJ.

1. 
   Ron_Brese | Jul 22, 2001 10:16pm | #2

   *b From the Workshop of Ron BreseSgian, The side in question had in fact cured for 8 to 10 hours. In the past I have used Behlen lacquers and have not experienced this finish printing. In fact I have been able to rotate carcass sides(considerably more weight) against a cloth cushion without finish printing after only 3 or 4 hours drying time. I will check with my supplier for more info. This could be a case of getting what you pay for.

1. 
   Sgian_Dubh | Jul 23, 2001 04:01pm | #3

   *Ron, I'm not familiar with Behlen products so can't make comparisons. I do know that ML campbell nitrocellulose and pre-cat's will imprint if you get at them too quickly. I don't remember exactly, but I think both really need about 24 hrs. after application to be safe from the phenomenom. Again, this depends a little on temperature, i.e., 70°F being the mean used to calculate such things. Also, if you've used retarder this can lengthen the risk period for imprinting. ML Campbell's post-cat lacquers seem to be free of imprinting risk very quickly as compared to the other two mentioned. As before, contact your supplier or ML Campbell for technical data. I tend to find this companies products generally reliable and user friendly as long as you follow the application recommendations and subsequent care in handling, particularly in the short term. Sliante, RJ.

1. 
   Ron_Brese | Jul 24, 2001 01:28am | #4

   *b From the Workshop of Ron BreseSgian, I contacted Merit Industries today and they in turn called the tech people at M.L. Campbell. Their opinion was that the heat and humidity that we are experiencing this time of year was causing the plasticizers in the lacquer to stay soft longer than usual. According to them the standard stack time of 12 hours would probably increase substantially during these conditions.

1. 
   Sgian_Dubh | Jul 24, 2001 04:31am | #5

   *Ron, at this time of year around here I intensely dislike spraying finishes designed to be sprayed. Heat and humidity seem to play havoc with your spraying and general finishing schedule. I wouldn't discount ML Campbell's reasoning as mere bull. My experience, although I can't fully explain it, rather backs up their theory. Currently it's typically about 95°- 100°F after about 10:30 am, and anything up to 80% humidity, and falling during the day, in my workshop. My experience is that the most problematic finishing jobs I've ever encountered have been on the US gulf coast where that aforementioned heat and humidity seem to do a number on me on an all too regular basis. Sliante, RJ.

2. 
   Ron_Brese | Jul 25, 2001 01:45pm | #6

   *b From the Workshop of Ron BreseSgian, Yesterday (Tuesday) I still had finish printing problems with parts that I had sprayed on Saturday. The first parts that I used the Campbell lacquer on had no such problems. Tuesday it occurred to me that those first parts had been base coated with Behlen lacquer. After testing to prove compatibility I used the Campbell lacquer for the final coats with no problems. The problems began when I start using the Campbell lacquer by itself.Going on this theory I sprayed one of the parts that was still finish printing with a good wet coat of Behlen lacquer. It was harder 30 minutes after I sprayed it than it had been after 3 days of drying, this morning it was even better. My conclusion is a formulation problem with the Campbell lacquer.

3. 
   Sgian_Dubh | Jul 25, 2001 05:15pm | #7

   *Ron, Interesting experiences you're having. I've been using ML Campbell's products for about 6- 7 years. Mostly I've used their pre-cat lacquer, vinyl sealers, tinted pre-cat lacquers and some of their stains. I have had some problems in the past, and one is Chinese writing in their pre-cat. I think it's sometimes known as crawling where the polish cracks across the grain and is due to too heavy an application, i.e., a dry coat thicker than 5 mils. Other problems have been orange peel, blushing, and a dried film rough or sandy to the touch. Most of these problems I've put down to the high heat and humidity I experience in these parts most of the year and my attempts to deal with the conditions. For instance the sandiness described is due to a failure to deposit a wet coat, so I compensated by applying a heavier coat with additional thinner and retarder added, which sometimes lead to orange peel, imprinting or crazing, and so on, and so on.Anyway, last August I decided to use their nitrocellulose lacquer for the first time because with the extreme conditions I work in at that time of year I didn't want to have to deal with possible pre-cat problems, which as you surely know is limited on the number of coats you can apply, three being the recommended maximum. Nitrocellulose can be applied coat upon coat and rubbed down later, and I was finishing a piece that wouldn't be subject to high abrasion or liquids lying on it. The upshot is that the conditions were so extreme that I had to gash a load of lacquer retarder in the stuff to get the gun to lay a full wet coat so as to avoid the problems I've described, and some of which you seem to be coming across too. I found that the polish took about six- eight weeks to really fully harden, so imprinting was a distinct possibility for quite some time. I put this down to my need to add so much retarder to the spray. I might check this Behlen's stuff out as you seem to be having quite good success with it, perhaps better than your experience with ML Campbell's products. I see their nitrocellulose lacquer is almost twice the price of any other comparable product. I wonder why? Is it that much better, or is it because they only sell in dinky wee quarts as opposed to the 1 gallon or 5 gallon containers I'm used to buying? Sliante, RJ.

4. 
   Ron_Brese | Jul 25, 2001 07:34pm | #8

   *b From the Workshop of Ron BreseRichard, Considering what I've been going thru this week with this lacquer fiasco, and when I think of how much money this whole ordeal has cost me, I wouldn't recommend "Putting Spit on a Dish Pan", unless you had tried it before and had been successful. In fact I would highly recommend that to anyone that has a finishing system or process that produces reliable results in a predictable time frame, to tide that horse till it falls to the ground, before changing. If it ain't broke don't try to fix it. Let's see I don't think that I can come up with anymore cliche that fit this situation.By the way nice table and chair in Woodwork.

5. 
   Sgian_Dubh | Jul 25, 2001 08:37pm | #9

   *Thanks for the compliment on the table and chair Ron. I haven't seen the article. I hope everything I said there made sense. That's the purpose for writing them of course, and er,.........and they do pay too, which is another reason for my drivellings. Plus at this time of year, given the chance, I like to hibernate in front of the computer composing them!As to the polish, you have a good point. It's nice to be adventurous with polishing, but sometimes the old tried and true is the safest option. My guess is that you are experiencing heat and humidity somewhat akin to to what I often have to deal with. Sliante, RJ.