I began using Scalecoat since about 1968 when several of my friends switched from floquil as their paint of choice. The only time that I saw a bottle of Scalecoat solidify in the bottle was about 5 years ago. Sattler's Hobby Shop had a new bottle of B&O Royal Blue straight from the manufacturer that was a brick.
Scalecoat originally had a rubber plug that was placed in the mouth of the bottle to prevent air reaching the paint after closing it up and it worked well, but I guess the cost became too much and it was discontinued. Since that time, when I closed the bottle after using it, I tighten the lid and turn the bottle upside down to store it. I have never lost a bottle of paint.
I use the small mixing bottles that are made for the Paasche H3 airbrush and when finished with the bottle, if there is enough for a rerun, I will cap it tightly and stored it upside down, labeled, for future use. Generally, I do not return the thinned paint to the original paint bottle.
I have had the paint in the smaller jar harden when stored upright, but found that was I had failed to tighten the lid tight enough and air got to it.
Floquil is a good paint, but you should really strain and thin it before use as, in my opinion, the pigments are very course! Once I have done that, I have never had any problem with it.
Until recently, I had an old jar of Scalecoat DGLE (Brunswick Green to the great unwashed), that was made up from three bottles of locomotive black and one bottle of Pullman Green back in 1968 that was still in good shape.
The EPA would not have liked it as it still had the lead base in it. I still have a PRR L1 2-8-2, a PRR I-1sa 2-10-0 and a PRR B6sb 0-6-0 that was painted with it and the finish is still in good shape today. That stuff was almost bulletproof. Today's Scalecoat will chip, even when baked, because the lead binder is no longer used. I guess some kid tried to eat an engine painted with it, so they banned that formula!
I still use Scalecoat and have found that it is a very foregiving paint that gives you a great finish when used properly!
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Newark, Delaware, 19711-7479