I bought several bags of play sand that I plan to use on my layout. What temperature and time should I use in the oven to ensure the critters are dead?
What critters? There shouldn’t be any if you bought the bag new
Even though you are using play sand, there are a couple things I would do. First, run a magnet through it to remove any metal shavings from the sand. I wouldn’t take any chances even with play sand because you just don’t want any metal migrating anywhere. Second, I would run it through a strainer to get different grades or sizes. You will find uses for these grades in your scenery. Then I would dry it out by covering a cookie sheet with a lip around the sides with aluminum foil. Spread the dirt out on the foil and bake it in a 250 degree oven for about an hour. Like I said I know you have play sand, but I wouldn’t take any chances. Hope this helps.
I have used playground sand which I am going to guess is the same thing as your play sand for sand casting, Like HaroldA I run a magnet through it and strain it into various sizes. Finally I run it through the microwave to sterilize it and kill any eggs which might be loitering therein.
I use the bagged WHITE play sand from the Big Box stores.
This has been steralized and it ALL is the same size of sand!
While I don’t like the white color so much - but it can be colored once glued down with a real thin mix of Latex paint (in the color of your choice) as the sand will take the color real easy.
I use this sand to make small terrain over the flatter areas around the towns & buildings. I just pour the sand out and let gravity make the little mounds.
Then I just glue it down with the 50/50 white glue and water.
I sometimes have to use windshield washer fluid to pre-wet the sand to get the glue mix to soak in.
Later on I will add the ground foam etc. to finish up the scene - but for the time being - it gets rid of the plywood pacific look!
As for any bugs - once glued down - the bugs are permanent residents of the scenery! Think Fossils ! 
BOB H - Clarion, PA
Great answer. Hadn’t even thought about the metal aspect. As for screening it down to various sizes, I’m not that fussy at this point and am anxious to get some sand on the layout to see whether I like how it looks.
Thanks to all for your help.
My ballast / dirt all over the layout was scooped up off the side of a mountain road, sifted, and place directly on the layout. No magnet, no baking, etc. Maybe I got lucky and my SoCal dirt was layout friendly?
Since it was already taxed to death, based on location, nothing would be alive in that soil anyway![:D]
For the sake of domestic harmony, I went to a resale shop and bought a used toaster oven to dry and sterilize the dirt I collect to use for scenery. It was all of $10.
Typically, i’ll run it for about 30 minutes at 500 degrees for a batch, which is usually a half-inch deep layer in the tray.
Be sure to do this outdoors or in a garage, as there can be a pretty strong odor from this process, depending on what was living in the dirt.
I agree I would do 500 degrees in the preheated oven for a half hour to kill off any unwanted “visitors”
Just because it is “sterilized play sand” doesn’t mena critters haven;t hopped onboard and or laid eggs somewhere along the way.
THe magnet is a good idea also. MAchines with metal parts may have left some goodies while it was processed and weighed and packaged.
I also use play sand in small zipper bags to hold down things on the layout while things are drying. Just be sure the baggie doesn’t touch any glues or you will have glued it to the layout where you may not want it!!
Something else to consider when using sand is the noise quotient. When glued down close to the track, sand tends to act as a sound amplifier.