Furniture, Wood and Cabinetry Finishing - Going from white stain to dark stain

I have oak stair railings that were stained a miniwax white pastel color. I want to go to a darkner stain. I have sanded it and used chemical stripper but there are still specs of white ingrained in the wood. When I apply a darker stain it shows through really bad. What can I do?

You have to get that white stain out of the pores of the wood to not have this show through.You have a more serious issues than most because the stain has white pigment in it which is even worse than a light wood tone as far as seeing through another stain is concerned.

you'll have to either try more stripper,as strong as you can use and with steel wool,stripping brushes etc and/or sanding until you remove the wood that has the stain imbedded in it.

Your situation is similar to a floor.It is sanded down to below the original finish before it is refinished.

How about using a gel would that cover the white pigment?

You would have to experiment and see.