The lead paint issue has been talked about many times here. Here is my experience. I am renovating the windows in my old house. I am certain there is lead paint on them. I sand at the end of the stripping process. I wear a mask when sanding and take a shower at the end of the day. I have had my lead levels tested and I am fine.

Now, if there are children around or you are a woman of child-bearing age, then you would want to look at this differently. But otherwise, IMO, this exposure is not particularly dangerous.

What type of stripping product are you using? You might be able to put more of the stripper on the areas that didn't come clean the first time.

Could you post a photo of the window and show us the problem areas?

I am using back to nature professional grade. It has blue lid. I put a thin coat over some stubborn patches and came back in a few hours. It helped a lot. I also used a wire brush, and cleaner. I am more optimistic today. Pictures attached are after cleaning. I will wear a lead mask when I do the sanding and will take precautions. I do have a 13 yr old child. My house is 1925 . Can you from the grain what kind of wood this is?

That's oak. Oak is usually harder to strip because the paint sneaks into the deep grain areas.

Sorry to hear your problem but I have been stripping old outside widows myself I feel the worst thing to do is sand it I never do that first dust goes everywhere plus nasty stripper I do not use aswell get a nice professional carbide paint scraper a little elbow grease and it comes off like shaving your face put a tarp down on the ground to catch all the waste do not worry about the low spot if they are smooth your painting over that anyway and the majority of clean area will adhere the paint over that now after you scrape it with a 2 inch wide carbide get a slight smaller or pointed scraper or similar sound like alot of time but it goes pretty quick with a carbide professional scrapper and they are not that expensive after you scrape lightly hand sand with 80 grit then 100 then 120 or now wipe down and paint it will be fantastis without all the dust from trying to sand it first before scraping and all that nasty stripper that you left on there will easily scrape off do not strip again safe your lungs and time and other time and lungs aswell I do it this way all the time the windows and or doors and trim go rather quickly with alot less mess and and alot less dust and fumes that go every where that you cannot control please do as I suggested safe your and others health and time! health