Finishing/Buffing/Polishing Redwood Slab with Oil-based Varnish thinned with Danish Oil

Question

I have a 3x5 ft Redwood slab with 1 coat of varnish/danish oil (50/50) mixture and 1 coat (last applied) of just varnish. I applied fairly thick coats for both layers.

The varnish The Danish oil

I scrubbed down the slab between the two coats with #0000 steel wool.

On the last layer, I notice that some application streaks/brush strokes are left over in the varnish as well as some nibs and what looks like a hair that must have become trapped.

I'm interested in finding the best course of action to obtain a high gloss/polished/buffed looked.

Questions:

First and foremost, is this kind of finish possible with the type of varnish I'm using?

Assuming the answer is "Yes":

1. How many more coats of varnish and/or varnish-oil layers should I apply before stopping?
2. To obtain a high gloss finish, what rubbing and/or polishing compounds should I use (links to products would be great!)?
3. As well as what method of buffing and polishing should I use?
4. I've assumed that something like this buffer/polisher would do the trick?
5. But I'm pretty lost on what compounds/liquids (as well as any other tricks/tips/steps) that I need to use in conjunction with the buffer/polisher on the final coat.

Thanks!

EDIT: Adding pictures of piece after recent 3rd coat of varnish + Danish oil: NOTE: coats are now:

1. 50/50 varnish + Danish oil
2. varnish
3. 50/50 varnish + Danish oil

Answer 1

On the last layer, I notice that some application streaks/brush strokes are left over in the varnish as well as some nibs and what looks like a hair that must have become trapped.

I'm interested in finding the best course of action to obtain a high gloss/polished/buffed looked.

If you want a high gloss you'll need to either A) cut back (even up the current surface and make it uniform) and begin wiping on thin layers of wiping varnish or B) build up the varnish and then sand smooth and buff.

First and foremost, is this kind of finish possible with the type of varnish I'm using?

It may be possible but it's not an ideal candidate, no. Firstly it's a spar varnish, which is inherently a little softer than varnishes commonly used for interior applications (this is intentional, it's what helps it withstand movement when exposed outdoors).

Secondly it's a satin varnish so has some matting agents added (all varnishes are inherently full gloss unless modified in some way). If you want a gloss surface you should use a gloss varnish ^_^

How many more coats of varnish and/or varnish-oil layers should I apply before stopping?

This is a "How long is a piece of string?" question because it depends on how thickly you're applying it, whether you remove some or all of the excess and at the end of the day how thick you want it. Short answer is, as many as necessary so that you don't cut through when wet-sanding.

As to how to perfect the surface, often referred to as 'rubbing out', the basic process is to build up, wait for it to harden sufficiently, flatten off, sand smoother and smoother (usually ending north of 1200 grit) and then polish to the degree you want using a choice of polishing agents and processes.

This previous Answer has links that cover the process in more detail, How do I remove scratches between layers of polyurethane? but there are a great many other guides to doing this online that have been published since.

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I applied fairly thick coats for both layers.

Just for general reference, it's better to apply a few thin coats than one thicker coat. This is a basic rule of finishing and applies in most cases.

While thicker coats can dry perfectly well (and some finishes are intended to be applied fairly thickly, spar varnish used outdoors being one) often you're better off applying more thinly and using more coats, your drying will be faster and more reliable, and perhaps surprisingly you can actually save time overall — this is particularly the case when it's more humid and/or colder, where thicker coats can take days to dry a very thin coat can dry enough overnight, or 8-12 hours.