I'm not seeing any ambering. What I'm seeing is a wood that has been made "wet" from a sealer/finish product. Ambering is much more ORANGE than what you are seeing. To test my theory, go ahead and use a WET (water only) cloth to wipe down a tread. You will notice the wet wood will look identical to your sealed treads. That will be the same colour as your finished oak treads. Your use of the WS EasyPrime is perfect for white oak. The Loba 2K Invisible Protect does not need a sealer. When you purchased the Invisble Protect, did you indicate that you wanted to use the sealer TOGETHER with the finish??? I would not add anything to your finish. In fact, I suggest you sand off the EasyPrime and start with the Invisible Protect. See if you can get the SUPER PALE finish you are looking for. But be aware. Your treads are different in presentation than your wood floor (both the cut and the width and obviously the selection of heart wood vs sap wood). The colours you are seeing are completely normal and natural to white oak in a "clear finish" (water borne products are normally rated as "clear"). The EasyPrime is showing you the colour you would get under a traditional water based polyurethane. You need to try some Invisible Protect ALONE on a tread to see if you can get a better match to your factory finished floor (which is EXTREMELY DIFFICULT BTW). Loba doesn't normally sell products that amber. You have to SPECIFICALLY request/purchase their AMBERING additive - which you did not do. That means the colour variation is down to the wood itself. And to be clear, your treads, over their lifetime, will slowly FADE. Yep. Wood traditionally gets LIGHTER when exposed to light. The oil based finishes are the one's that turn a STRONG ORANGE as they age. White oak can fade quite nicely. I think the WS EasyPrime is giving you the slightly darker look of "wet wood". I would guess the Invisible Protect will give a lighter presentation. https://www.loba.de/fileadmin/site_structure/produkte/11474/us/BRO_US_11474_2K_InvisibleProctect_AT_Flyer_US.pdf

I have to agree that these were preexisting but almost invisible because of the sanding. The top pic looks like "old finish" was left in place. Considering how thin your boards are and how old they are, this is not unexpected. And to be clear, old floors can have 80 years worth of contamination (ie. wax, shoe polish, Pledge, Murphy's Oil soap, soap, hairspray, hair dye, etc) on them. These products can, and will, get past the original finish and contaminate the wood. Just like old urine stains pushing all the way through a board (the dark gray stain is most like an old urine stain...cause that's what they look like after many years), these contaminants can go several millimeters into the wood. Especially things like cooking oil, Murphy's Oil soap (anything oil based really) or even melted wax from a candle. After sanding, you wouldn't have 'seen' these things. But a quick swish of a slightly damp mop (make it wet to give some depth of colour) and all of these things would have been evident within moments of the water touching the wood. And that's why you can see them now. The clear coat is like water hitting the wood. It gives the colours depth...and definition. But unlike water, the finish is permanent. At this point, I would keep going with your plan = 2 more coats of Loba 2K Invisible. And You will want to hurry. To get a good 'stick' the next coat should be put down within 24 hours of the previous...or else the flooring guy has to abrade the floor again to get a mechanical grip rather than a chemical stick. Keep going. Know that you are getting 20 years more out of these floors that probably should have given up the ghost 20 years ago. That means you are extending the life by 40 years. For an old hardwood floor, that's impressive.

I labored what to use on my oak floors, I decided on the Loba 2K invisible.. I read , watched video's and then ordered. Took me 2 weeks to be very precise, I sanded via machine with 40, 80 and 100 grit. My floors were in decent shape to begin with, the water based finish had given it that amber look 15 years ago, I realy was tackling my kitchen and decided why not do the entire floor. I used a machine sander 40, 80, 100 grit before applying the first coat. I purchased the Loba roller and watched many video's, I applied cross grain in sections, then without applying any more liquid, went with the grain to blend. I awoke the next moring with white lines cross grain. I should have reached out then. But, NO, I used the 100 then 180 on a buffer -using the perforated pads suggested and then applied the second coat the same way. 24 hours later, same problem, I have lines cross grain, I am nauseous. An expensive product, time consuming. due diligence. I am rehabbing my home so I am not without skill. The sanded floor looked great. I will call tech support tomorrow to see if there is anything I can do. The only other additional detail - I used the whitener in the first batch only.

Thanks very much for that G&S Floor Service, I’ve had a look at the product range on the official website and we don’t seem to have Nordicseal/Naturaseal as well as Bona Craft oil. I’ve attached a screenshot of the product range and Prim Intense for reference. I had the site inspection done this morning and he tells me that regardless of methods dark water damage marks can’t be removed or toned down much - he tells me bleaching causes problems down the track. 3 options were given to me: Bona White (1-2 coats) and then 1-2 coats of Bona Traffic (HD) - he seems more comfortable working with non-HD product as HD dries too fast he says. If 2 coats of Bona White are applied then only 1 coat of BT (HD). He tells me there is not much difference between HD and non-HD in terms of durability. Staining with non-Bona products as Bona staining products are not very good and then finished with BT (HD). He also doesn’t recommend going with this method as it takes much longer (1 full day working solo) - his boss tells me that for intensity of white effect Drifast stain and Prime Intense are not as good as 2 coats of Bona White. The guy who came out tells me Bona White can be applied by a roller and would be easier. Natural wood colour - by sanding and finish with 3 coats of BT or BT HD. I get the impression that they would want to do the job in an easier way since these guys work solo. They tell me that they’d take 1-1.5 weeks for 145sqm floor size.