How do you get a closed pore finish on mahogany? I have been trying for a long time without success. I would sand the sealer flat, no pores showing, and when I put the topcoat on, the grain would appear again. I am looking for a sprayable solution instead of sand and buff. Any advice?
You didn't say what you were using. I would use a self-seal conversion varnish or go up to a higher-end product, like a two-part polyurethane base coat and two-part polyurethane topcoat. If you are staining the wood, you can use either a filler stain or filler glaze stain to help fill the pores.
I have looked at the PianoLac specs, and waiting 3 to 10 days to polish would put me out of business. My jobs are always "hurry up and wait" or "I want it yesterday." I just need something fast. I usually build then finish in a small shop, so I would need a system that will keep me working till I get it done. In a small shop, I can only do one thing at a time - build or finish.
This MLC product is meant to sit in the wood pores, not on top of the wood. This is unlike the polyester and 2-pak urethanes which can be built up on the wood and then topcoated.
And you should apply your wiping stain before applying the A.C. Sealer. What that means is that you have to do some practicing so you will get a feel for how much to sand off and when you have sanded too much off (leaving you with sand-throughs in your stain coat).
Within about 40 minutes of applying the A.C. sealer you are ready for topcoats. Is shrinkage still possible even with the use of the A.C. Sealer? Yes, but it's very little.
I have a friend from Oregon who uses Duravar (a catalyzed lacquer) in such a way that he gets no shrinkage and he completes his spraying the same day, ready for rub out soon afterward. First, he uses Martin-Senoir's Acrylic Enamel Reducer (only 20% by volume) for the Duravar instead of the MLC suggested reducer. Second, he starts out with his filling by spraying dustcoats and light sanding. Then he sprays his full wet coats. He has repeat customers, no call backs and years of experience. But before I suggest that anyone try this maverick approach to using Duravar, you ought to have him detail you the steps himself.
In all this, I think that without big drying ovens for you to use, you have to rely on the passage of time.
This procedure will release remaining solvents and cure the coating, ready to rub.
If you've been spraying thin coats and filling the pores as per the advice on the website, shrinkage will not occur. This may seem an outrageous claim, but I have finished over 20 grand pianos, most of them Steinways, for very critical customers, with PianoLac. I followed up on them in the customer's home, and there has never been one instance of shrinkage.
After staining, use a 2K urethane isolator.
Polyester grain filler. Grind down with a random orbit sander. This is the best grain filler on earth. Nothing else is even close.
Either polyester or 2K topcoat. Grind down with fine paper and ROS.
Automotive rotary buffer and compounds to high gloss.
I know that this works and is permanent. This system is completely devoid of thickness limitations. Put it on as thick as you want.