I hate poly

Thane_Bitter

Working on a wood project (pff, I wish, it's MFD - Mostly Found saw Dust) and made the mistake of using a polyurethane finish on the cut edges (the material was made with a finish, I only needed to do something with all the cut edges). Two days in and it is still tacky, it can't be humidity related because its under 40%, temperature is around 68 freedom units. I meant to put a fan on to blow air around last night but forgot (the joys of aging).
Putting it on this morning seems to be speeding up the process. But I think it will take a week of drying, more sanding and coating before this simple little project is done. I would have used banding (edge banding) but they carry every other colour but a dark walnut.

What is your favourite topcoat and why? At this point I am leaning towards real shellac and mixing it myself from raw flakes.

Somewhat-Reticent

Thane_Bitter ( Any stain/primer first? MDF = Medium-Density Fibreboard? )
Polyurethane stages - dry first, then cure (cross-link). Longer if thick. Durable when done.

Zach

I agree, regular slovent-based poly can be a slow curing, sticky pain in the backside. For indoor, above the floor work, I've had good results with Varathane water-based. While it typically requires more coats than regular poly, it's pretty easy to work with, doesn't usually require sanding between every coat, and can usually be recoated in 2-4 hours. Assuming I don't screw something up, I usually apply 6 coats, sand between coat 2 and 3 and before the final.

https://www.rustoleum.com/product-catalog/consumer-brands/varathane/ultimate-polyurethane-water-based

I use laquer on a few projects. The finish is harder and looks a little better to my eye than poly. However it's tricky to apply and dries FAST. Keeping a wet line is nearly impossible on larger projects without spraying. As well, the odor is quite overpowering and potentially flammable without adequate ventilation until cured.

I've used shellac with success. The odd thing about shellac is some items placed on a shellac finish basically melt into finish. The brown cord on a lamp 'melted' down to the wood top everywhere it made contact. 🤔

Thane_Bitter

Zach I was told by a woodworker (I think they primarily turned pens and made electric guitar bodies) that winter was the only time he would do lacquer finish, the fumes are overpowering and up hear with the heat and humidity of summer the prospect of doing it seems like a painful suicide. I like the idea of the stuff, its natural (or at least used to be) and certainly there are many examples of how long lasting and durable the finish is.

Interesting about the lamp cord, I wonder why that happened, if the finish still had some solvent left or that the stuff in the cord out gasses something that eats into the finish.

I guess this is why epoxy finishes are all the rage, you get the look of a wet finish that is highly glossy and of course it's rather durable and strong.

GrumpyCanadian

Zach I use laquer on a few projects. The finish is harder and looks a little better to my eye than poly. However it's tricky to apply and dries FAST. Keeping a wet line is nearly impossible on larger projects without spraying. As well, the odor is quite overpowering and potentially flammable without adequate ventilation until cured.

I haven't tried it, but apparently one can get low-VOC, water-based lacquer. From what I've read, it still dries quickly, but the stench is mostly eliminated.

Thane_Bitter

Somewhat-Reticent Yes it was stained medium density fiberboard. First coat vanished into the material rather quickly. It might be that the stain was still outgassing, its solvent first going deeper into the material first, but the surface was dry before the first poly coat.

I did put a fan on to help move the air around, that seemed to help speed up the process, temp and humidity stayed about the same. Final few coats were left to dry hard, sanded with 500 grit, before the final coats. Overall not bad, MFD was cheaper than particle board but it's not as rigid. It's also more sensitive to holes size, with particle board I had no issues with splitting, but with the MDF using the same type of screw (confirmat type, hex head) some of the smaller pieces required extra reaming to prevent splitting.

Zach

GrumpyCanadian Thank You! I will look into it.

GrumpyCanadian

Zach I just bought a small can for some basic work that I have to do. I haven't used it yet, nor even opened the can, so I can't comment on usability, quality of finish or stench. However, I found it interesting that the can claims a VOC content of 226 g/L, while the traditional WATCO stuff is typically over 650 g/L, with that lingering, flammable stench. If it's any good, I'll switch permanently, for the limited amount of work that I do with it.

Zach

GrumpyCanadian After you mentioning they exist, I went searching and have come across a few water based laquer products. One is even a pre cat. The problem I'm finding is they are almost universally adorned with my favorite sentence: Not for sale in California. 🫤 I have workarounds for this problem however it's a pain on short notice. I have four cabinets to get done and will have to use the old-school stuff which is widely available here as is the equally volitile thinner. Glad the State knows what's best for my lungs. 🙄