Wipe-On Lacquer
 

I am doing a few things to spruce up a house I will sell. 1953 craftsman. Some of the window sills are very tired. Failed finish, missing in some spots, discolored or worn. My plan is to do a little light sanding, which will leave most of the lacquer in place, and then apply a thin coat or two of new lacquer. I feel pretty confident the original finish is lacquer.

I am not trying to refinish these sills. Just make them look a little less distressed.

I have thinned polyurethane before and applied using a lint-free paper rag (from an auto body shop) with good results. I wonder if this is the technique I should use to apply lacquer.

I've done alot of finishes over the years. Typically lacquer is always sprayed. Some of the Minwax
polyurethanes are wipe on and can look very nice if applied properly. They also come in satin,
semi gloss and gloss. If lacquer is the base you can safely topcoat it with most other finishes.
Someone else my chime in on wiping lacquer but I think you would end up with a sticky mess.
There is also Rubio Monocoat. I have not used it, but you might want to look it up on some
YouTube videos. The wipe on polys might be the easiest to use though. They also can be
sprayed with good results.

Thank you. The poly would be easy to apply, but I just wonder if it would play nice with the existing petrified lacquer.

To check if it is lacquer, get a white rag and wet with lacquer thinner and rub the painted surface, it should pick up the colour pretty fast.

As far as I know you can put a softer paint over a harder paint, so poly works over Lacquer.

But if you have lacquer finish and are able to find some lacquer paint I would stay with it. Keep in mind most of what is in the lacquer paint is lacquer thinner prob about 90% of it, so quite flammable. Should be able to apply with bristle brush, likely dissolve most poly brushes. Inside a house I would want lots of ventilation and only work on small areas at a time.

These window sills are clear lacquer over wood. I don't think poly existed in 1953.

Perhaps a bit of diluted (wipe-on) poly is the best idea.

Keep in mind that lacquer is pretty clear, while the poly's tend to be a little more
amber which can alter the look. Try one sill first and see what happens. The Minwax
polys are fairly thin to begin with so don't over thin them. Sand,use tack rags then
good brushes or rags to apply.

It's really the bottom sills that look ugly. And really, mostly just the one behind the kitchen sink. It really just needs to be replaced, but I am not a carpenter. I can build tube amps. I can rebuild Porsche engines. I cannot saw two boards and have them fit together.

If you think it really is lacquer be cause of the age then it would be nitrocellulose lacquer.
To test this you can use a q-tip dampened with acetone to see if it softens and pits. I am guessing what you have is shellac which you can test with isopropyl alcohol or denatured. It will soften very quickly.

That is really helpful. This suggests I can identify whether it is shellac or lacquer. It also suggests I could strip it. At least....the kitchen window lower sill. By using acetone or alcohol.

Wait. Isopropyl and denatured (ethanol) are two different things. Are we sure that either will dissolve shellac?

I think alcohol of any type will dissolve shellac IIRC.

Don't strip it unless you absolutely have to. I bet its lacquer too but how old is the house? Use this, Deft. Its self leveling (to an extend) and it will stick to lacquer.

Depending on the condition of the exiting finish, brush on, sand between coats until absolutely flat. Mask off and rattle can. Thin coats. Now that's already a lot of work but I bet your buyer isn't going see the brush marks if you did the last coat with a brush.

Do not go over varnish or enamel, possibility poly. too.

https://www.woodworkingshop.com/product/PARDFCLEAR/

Here's the product. I suggest semi or stain to hide brush marks or imperfections. Anything glossy, the imperfections will read like a book

Rattle can lacquer works so well now with the wide, flat spray tips. No sputtering and furniture quality finish. The time is in the prep and masking. If I was doing a kitchen full of cabinets I'd load my airless but rattle canning smaller projects and not having to clean my spray equipment is so nice. Another thing to consider using lacquer in an inhabited house is the few days of stink.

I would sand them with 150, and as long as the color is not too bleached out, coat them with
waterbased poly like Polycrylic.

If you need a little color added, wipe them as evenly as you can with oil based stain, gently wipe off excess 15-30 minutes later and topcoat with the Polycrylic the next day.
Since the wood is already sealed, the stain will act more like a glaze so be artistic when removing the excess.

The waterbased will stick to any existing finish as long as it is prepped properly.

Careful with that. Oil base stain must dry completely and many do not because its been applied to an existing top coat so it just sits on top and water base clear will not stick to it.

Hit it with 220 or 320 grit (I like 320) and see if some of the marks come off. If not the other trick is to build it up with a brush on the low spots (chipped or worn away finish) let dry and apply more on that spot and sand away a bit until flat, spray last coat or brush to finish.