LYNN – It sounds like something out of science fiction, but spontaneous combustion is a very real fire danger.Fire Lt. David Legere said chemical reactions involving cloth items soaked with petroleum or other chemicals and the container they were stored in started four fires in the past year.The most recent one ignited Monday night inside the former Towne Paint Supply building at 21 Neptune Boulevard.Legere said oil-soaked rags stored in a plastic bag covered by sawdust caught fire shortly after 11 p.m. He said workers converting the building into a restaurant had been using the rags to varnish wood.Firefighters extinguished the blaze in a couple of minutes, confining it to a small area in the building. A similar fire caused much more destruction to a half block of Andrew Street on Feb. 1.A chemical involving work gloves used by workers handling cooking grease started a fire that gutted the American By-Products building and two adjacent storefronts.Legere said the spontaneous combustion reaction started in the gloves after they had been cleaned and dried.”It slowly built up heat and started smoldering and smoking over a period of three or four hours,” he said.By-Products was closed the weekend after the fire broke out, but General Manager Phillip Bruno spent the two days after the fire arranging spare trucks and contracting with Lynn-based Cutillo Welding to start demolishing the fire- ravaged structure.By-Products resumed business on Feb. 4 and set up a temporary trailer for Hatch Hearing Aid Center in a parking lot across from Hatch’s gutted storefront.The fire also forced a church congregation and a law office to seek new locations.Another combustion blaze started in the Lido Restaurant’s basement and caused less damage than the By-Products fire.Legere said cloth items coated with oil or other chemicals should not be left in piles on or near material that could catch fire.”I don’t think people realize the danger of this,” he said.