Hi Randy,
That's a pretty admirable piece of wood!
Know, however, that you are treading on soft ground (ha! pun intended!) when you talk about just slapping on "some epoxy" and expecting all your problems to be resolved.
Let me explain some of the pit falls.....not least of which is ......just in the way the skin of an apple does not fully protect the rotten parts...neither does a thin film of epoxy totally protect the surface of your softer wood parts against all brutality totally and completely....(but yes, it does help, especially if you do the sealing/soft part absorbing first steps properly....read on! ).
First (well, last, but most recent question).....yes industrial or professional grade two part chemically hardening urethanes are way harder and much more abrasion resistant than pretty much all epoxies......do not confuse them with regular run of the mill retail store poly's that are rubbish by comparison and not remotely in the same league....they are also much more expensive and typically contain isocyanate hardeners (= nasty stuff, not for use by amateurs or without proper PPE and or correct ventilation.)
There is also a big difference in the hardness of epoxies themselves....some of the cheaper one are actually very soft and scratch easily....while the harder more expensive ones are as tough as a rat's teeth (which, incidentally are 6 on the MoH hardness scale....human teeth are approx 0.5....diamonds are 10 by way of comparison....how do I know this?....I am presently involved in a rat war and I am losing....this rat likes fridge wires and internet cables the sneaky little rodent...but that is another story).
Next....you can put a typical poly on top of an epoxy if you want, thereby getting a different sheen but know that all epoxies have a recoat window (read the data sheet) and if you exceed it then your poly will not stick well and may peel off in spots and then you will be mad, specially as it will be all your fault...so yes you should scuff it lightly and uniformly before you put the inferior softer coating on top. Better yet, don't go that route at all (again, ...read on).
Prior to that you will find that simply pouring on the magical epoxy glop to your wonderful looking wood will result in greatly different absorption of the product and in some areas it will get sucked in and in others it will sit on top and the result will be irregular and not very nice at all and you will say "This is no good"...and you will be correct.
Like with any soft irregular substrate (such as inferior concrete floors...and I've done 100's of thousands of square feet) you need to seal the substrate first....and this may take more than one thin "seal coat" application to achieve or you risk a rough nasty looking result....sealing it properly also gets rid of the tendency of the wood to outgas and cause annoying bubbles in the surface of your thick epoxy (that's also a temperature related problem that you should find out about....and how to deal with it...your epoxy should go on a cooling substrate not a warming, temperature rising, substrate, in which any trapped air is expanding, albeit only slightly and hence outgassing.)
You can use a thinned version of your topcoat epoxy (careful what solvent you thin it with, Varsol ain't it!) or a different (but compatible) clear type epoxy to do the sealing.
Again....be careful of the recoat window and do not exceed it.(read the data sheet...if you don't have it....then get it, you will need it!)
As a side note, you can under-seal a surface (still needs another coat) but you pretty much cannot "over-seal" a surface, especially if you have soft highly absorptive areas......if you are even remotely concerned about "did I seal it enough".....then put on another coat as its too late once you pour on the finish coat.
Speaking of which...epoxies are very temperature sensitive and if its cool (like your garage?) you will have a much longer recoat window (or way shorter if very warm)...to say nothing of the fact that at cooler temps your thick viscous product may not flow out or level in the way you want it to, it may just sit there like a cow pat in an unseemly fashion.
Even when the surface is "sealed" .....you may be wise to pour a thinnish levelling coat on the entire thing first and let that cure up before you pour on the "final" coat with gay abandon......the whole key here is careful attention to the details BEFORE you get to what should be this last glorious step if you want to get the results you hope for.....it is not as simple as "just pour on the great stuff I got yesterday and it will be great.".....doubtless the stuff is great but only if you do all the prior steps fully and completely.
BTW if you have holes or deep cracks, fill and block those first or much of your topcoat will simply drift down and through and away.
Lastly, as to the gloss or sheen level......you would be far wiser to adjust the shine by sanding it back down to whatever level you desire unless you have spray equipment and the correct sheen and type of industrial 2 part urethane or conversion varnish...but I suspect if you did have that we would not be having this conversation, right?)
Don't worry.....we can get there from here anyhow....it just takes a little longer (and, if you are like me, you may have more time than money).
Let it cure fully and complete and hard..hard..hard.....know there is a big difference between "dry to the touch" and "fully cured" for sanding purposes.
If it gums or globs, drags or sticks even a wee bit when you scuff it....it ain't cured enough!
You may need to let it sit for week or more before you can buff it down......then simply use very very (very!) fine sandpaper or wire wool and be nice and gentle and even and patient.
The good thing about this approach is you will have no adhesion problems down the line, its cheaper and it can be repaired or fixed up easily at any point in the future plus there is the zen of buffing out a finish to be enjoyed.....to say nothing of the fact your friends will all come for miles to admire it and will amazed.
Good luck!
Onwards to victory.
...and post a picture when you done so we can all admire your hard won result.
Julian.
