Although I primarily use acrylics, I sometimes use enamels. I find that MM enamels don’t last long once the bottle is open. I even tried to prolong the life of MM enamels by sealing the bottles with a kitchen wrap but to no avail.
How is Humbrol in terms of longevity?
My first use of both Humbrol and MM enamels didn’t result in stored remaining paint lasting very long, but I read you don’t want to put thinned paint back in the bottle, (or tin.) Since then, any left over of thinned paint just gets ditched when spraying is finished.
Also I think it’s really critical that the container be kept meticulously clean, around the threaded areas of both the bottle and the cap. For that reason I never shake the container to mix the ingredients, I first stir completely with a stick to loosen all of the really thick solids at the bottom, then use the Badger or other little electric mixer to get a fully blended paint.
I don’t pour the paint over the bottle edge, I draw it out with pipettes, that way the threaded surfaces remain clean. Your idea of kitchen plastic wrap is a good one, I do that as well, can’t guarantee that it works, but it sure can’t hurt.
Now, by being careful with the bottle handling, I find I can store most any enamel for several years. Rarely do I find it gone bad due to drying up.
Humbrol seems to last a very long time for me as well.
Patrick
Although I always stir Tamiya acrylics, for some reason I always shake MM bottles with metal beads inside. That obviously makes threaded surfaces dirty and I don’t clean them after a paint session. Perhaps, that reduces the longevity of my MM enamel bottles… I never put thinned paint back in the bottle.
I’ve managed to keep both Humbrol, Colourcoats and MM for several years–and I do thin them as soon as I open them; about 50-50, with lacquer thinner, so they are always ready for airbrushing right out of the bottle.
I used to add some Floquil “Glaze” to each bottle. It seemed to work with all the brands of paint I use. Supposedly it helped both preservation and airbrushing. It’s no longer available; discontinued along with the whole Floquil line. I don’t know if there’s a suitable substitute.
I always decant Humbrol and Colourcoats into a glass bottle. You can buy empty mixing bottles at Tower Hobbies, Micro-Mark and/or Amazon (although they sometimes don’t have them).
It’s only my preference, but I don’t find the metal tins as handy as a bottle with a twisty lid.
I’ve read before that thinning the paint will reduce it’s shelf-life, but haven’t personally encountered this. Of course, I don’t think I have any paint much older than ten years.
In my experience, I have found that Humbrol paints tend to last far longer than MM enamels- as long as the tin top and lid do not get damaged to where they no longer properly seal. As much as I like Testors MM Enamels, I have never gotten the same longevity out of them, and in recent years I have noticed a serious drop in that aspect of their quality control.
Hmm…poor quality control at MM. In last August, I used two brand new MM enamel bottles. Then I sealed both bottles with a kitchen wrap and stored them in a closet. I opened them a few days ago only to find gooey messes in both bottles.
I use both Model Master and Humbrol and so far I haven’t ever had any longevity issues with either brand. I have some bottles of MM that are over 5 years old and some tins of Humbrol that are older. Recently I have taken to getting my Humbrol tins directly from the UK since my LHS carries a limited quantity and since my other half is from the UK with family still there it turns out to be cheaper for me. In fact her family has also started to send me the tins of the Revell paints as well which is nice to have on hand.
Sometimes the MM brand can be old bottles sitting on the display shelf. Believe me, I’ve picked up my fair share of gooey, gummy paints - particularly Gunze - only to return them for an even exchange. That’s why I always open the bottles to see what condition they’re in before buying them.
I’ve generally had better luck storing MM Bottles than Humbrol tins - however, i echo Patrick206 that the thread and lid interior of the bottle should be meticulously cleaned prior to closing. I’ve got a few bottles that are now 8 years old and good as new with a stir up.
Never gotten more than a couple years out of Humbrol - i find the tin tends to distort slightly after multiple openings and it’s harder to keep clean. I often find Humbrol tins have turned to goo after a few years, despite my best efforts to keep them nice and clean.
I have had several MM enamels turn to a gel-like substance after awhile but that has never happened with Humbrol in the little tins. I have some Humbrol silver(#11) that is probably close to 30 years old and while pretty thick, with a bit of thinner it’s still viable paint. I’ve had to scrape dried paint away from the edge of the Humbrol tins a few times in order to get a good seal with the lid. I use enamels almost exclusively and my collection is about evenly divided between MM and Humbrol. The fact that I’ve never had Humbrol paint “go bad” gives it the edge imho…[:D]
Gary
Yup, what he said! I have some Humbrol paints in my paint collection that are nearing 30 years old and still are good once stirred and thinned if need be. I have some older MMs that are over 20 years, but those are rare exceptions. I had a new recent purchase of a newly issued color from MM go bad after one use- nearly a full bottle that turned to a rubbery gum that could not be used. If both companies make the same color, I will opt for the Humbrol Enamel. Why? Because I know I will likely get my money’s worth. If only MM makes the shade I am looking for, then I buy it from them… and hope that it will not go bad.
I need about 10 colors for painting details and dry-brushing, and that’ll cost me about $30. I don’t want to deal with gooey MM enamel messes.
10 Humbrol tins will cost you about 1/3 less. They have their quirks and must be stirred thoroughly, but no enamels will give better results once you have mastered hem.
I love working with MM enamels, but their short life is indeed a problem. Unopened they last a long time, but once opened they go bad pretty fast. Once thinned to airbrush consistancy they go bad even faster 
I too have some Humbrol tins well over 30 years old and are still good. I also have some Testors small bottled enamels about the same age that are also still good.
The quality control issue mentioned is a big reality as I have purchased the small Testors enamel paints recently, only for them to go bad in less than a year!! [:|] I also find that they don’t cover as well and evenly as the older Testors enamel paints.
Here is a tip…For Humbrol tins I always have little squares of aluminum foil handy and always clean the lid close the jar and seal with the aluminum foil over the top. I dab a little color on the foil to know what color it is. The foil will last the life of the paint.
This works very well. Humbrol paints need to be stirred very well, more so than any other enamel.
I love Humbrol for many applicatons their flat white and flat black are the most opaque and useful of any manufacturer for brush painting.
Testors MM enamel the only tip I can give is to clean the lid with a q-tip every time, and wipe the jar top to the glass.
These little extra efforts are worth it, for paint that is about $300 dollars a gallon.
One thing about all of this- you never really know how old the paint is when you buy it. Esp. these days if it’s at an LHS- it may have been on their shelf for years or even decades.
That said, I have Humbrol tins that are probably 10 years old and still give good results. I don’t think I’ve ever had one go solid. Thats happened too often with MM.