Wood Preservative Clear
Flood CWF-UV 1-gal. Clear Wood Finish
https://www.lowesforpros.com/pd/Flood-CWF-UV-Clear-Exterior-Stain-Actual-Net-Contents-128-fl-oz/999978922 $19.98 was $17.08
I prefer the clear version rather than the "cedar tinted" version even though the clear version is $1 more. Apply with plenty of ventilation to get rid of the VOCs, but does not contain particularly bad ingredients so ok to use internally.
MSDS: http://www.homedepot.com/catalog/pdfImages/a1/a14b62b9-a704-46b2-a92e-9e2d1968585f.pdf
Can then put varnish over it...
Varathane 1 gal. Amber Gloss Interior Polyurethane (Case of 2)
http://www.homedepot.com/p/Varathane-1-gal-Amber-Gloss-Interior-Polyurethane-Case-of-2-266250/203326145
$64.92 for 2 gal
Note this is amber color, but might be ok. Currently
best bet.
Epifanes varnish very expensive but might be best bet for front door.
Tung oil is also a good solution (also works outside)...
https://smile.amazon.com/gp/product/B007RO1Q5U/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 $22.98 + $0 + $0 for quart
https://smile.amazon.com/gp/product/B007RO1PJC/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A3L90ILH9AHNA6 $55.99 + $0 + $0 for gallon
https://www.realmilkpaint.com/category/oils/