A Question About Lacquer

I am doing my first finish on my partscaster, and I was wondering if laqcuer really has to cure for so long. I've read that it has to just sit around for about six weeks, but that seems a bit extreme. I thought a week at most would be sufficient, but you guys are the experts. So, how long does it take?

It dries on the outside then cures underneath forever...when the smell goes away it's 100% dry, can take months...

Can you play the guitar while it dries underneath the top coats?

You can handle it, here's more detail...the best is to hang it up and forget about it for awhile...

http://www.tdpri.com/forum/finely-finished/201307-how-do-you-tell-when-lacquer-dry-enough-sand.html

http://www.reranch.com/101a.htm

PM Colt W Knight...he knows the drill...

If you put the hardware on your guitar too soon, you'll dent the lacquer. It's worth the wait.

If you wet sand it too soon your going to be doing it again later. It might look level now but in one or two months after it shrinks a bit it wont be level anymore and you will notice alot of imperfections that you thought you sanded out.

After the clear coat. I should tell you that using clear nitro from Reranch gets the best results that I have seen. 40 years if surface discoloration in 2 weeks or less.

Not with a good job of grain filling. With sanding sealer alone, yes - to a point. But you can offset even that a bit by doing a good job of presanding and applying multiple coats of sanding sealer.

The sanding sealer and the lacquer used also makes a difference. The higher the solids-by-volume the less shrinkage; also, some resin blends shrink more than others. It takes applying many, many different brands and types made by each brand (in the case of bulk or professional lacquers intended for trade sales, like Mohawk, who has several aerosol sanding sealers and clears) and watching the pieces over time...and on different types of wood...to be able to predict shrinkage.

Depending on what I'm trying for as an end result I may sand in two weeks...or an hour.

Also, (and this may be a surprise to long-time finishers...it was to me) with most of the good grades of fine abrasives made today wet sanding is not necessary. You can dry sand with absolutely no lubricant and get the same results. This is a good thing, as wet sanding can cause liquid to soak into screw holes, open end grain and all sorts of spots, changing the results once it dries out - or causing blisters if the areas are sealed later.

Not with a good job of grain filling. With sanding sealer alone, yes - to a point. But you can offset even that a bit by doing a good job of presanding and applying multiple coats of sanding sealer.

The sanding sealer and the lacquer used also makes a difference. The higher the solids-by-volume the less shrinkage; also, some resin blends shrink more than others. It takes applying many, many different brands and types made by each brand (in the case of bulk or professional lacquers intended for trade sales, like Mohawk, who has several aerosol sanding sealers and clears) and watching the pieces over time...and on different types of wood...to be able to predict shrinkage.

Depending on what I'm trying for as an end result I may sand in two weeks...or an hour.

Also, (and this may be a surprise to long-time finishers...it was to me) with most of the good grades of fine abrasives made today wet sanding is not necessary. You can dry sand with absolutely no lubricant and get the same results. This is a good thing, as wet sanding can cause liquid to soak into screw holes, open end grain and all sorts of spots, changing the results once it dries out - or causing blisters if the areas are sealed later.

Care to share some good quality abrasive sources? I hate wet sanding. My spray technique leaves very smooth results these days, and I don't have to sand a lot. So if I could get away without using any water at all I would be a happy camper.

I use these products almost exclusively for instrument work:

http://micro-surface.com/index.php?main_page=product_info&cPath=273_193&products_id=88

They have a zillion products (I got into them in my "other life" in the coatings industry, where a lot of fine-finishing and faux-finish craftspeople use them), so to narrow it down, if you hit the link look for the 3"x4" soft touch "regular" pads. The assortment is a good place to start, with grits starting at the *equivalent* (IMPORTANT - we'll get back to this) of 400 wet-or-dry and going all the way to what would essentially be 14,000 grit - which will generally polish whatever you just polished with the usual liquids or pastes.

The on thing to be aware of is that their grit numbers are NOT equivalent, so it's good to keep the sheet from the packaging handy to help you until you get familiar with the differences.

I've bought the 3"x4" sets and keep a set that I've cut down to get me a 2"x2" set plus a 2"x 1" set (cheaper than buying the 2" x 2"). I also like the cigar-shaped type - great for working inside cutaways, cleaning up edges of control cavities etc.

If you have a Rockler store near you they usually stock both of the assortments I mentioned plus a bunch of single-sheets in various grits.

The stuff *appears* expensive - but as it's essentially non-loading (you can brush off anything but really sticky stuff, which you shouldn't be sanding anyway) for lacquer and woodwork I find a usual pad set lasts me a year or two - and I use them every day. I'll temper that by stating that I've bought a few sets over the years and have no idea which ones are the oldest!

Like Colt I use them less for finish coat sanding and more for primer/sealer/filler work and fine-sanding the non-finish-sanded "finish-sanded" bodies sold by most major outfits. However, I *do* use the "beyond 2000" grit pads either as final prep for or in lieu of final polishing. If you work your way through the grits and finish with the ultra-ultra fine gray you'll have a mirror-like gloss without ever touching a buffer.

And while you CAN wet sand with these I recommend NOT doing it. First, there's really no reason to - the abrasives are totally different. Second, the abrasive sheets on the pads are glued-on, and when I still wet sanded everything from force of habit I found the adhesive eventually loosened (OTOH it glued right back together when dry with contact cement.

I find the pads a distinct advantage over small wood blocks (or 9V batteries, which are not necessarily flat!) - they handle curves and rounded edges beautifully and it's easy to control the pressure. I've even taken wood or sheet metal, shaped a curve and used it as a backing for a series of pads. If there's anything better I have not found it yet.

Hope that helps. They are products that have definitely saved me a load of time and money.

Here's the best source I've found for Micro-Mesh: http://www.sisweb.com/micromesh/.
I buy the 12x12 sheets and cut them into eight 3x6 sheets. Micro-Mesh is not as expensive as it seems because a sheet lasts a long time. It doesn't load when used wet. When I've used it dry it seems to load similarly to conventional sandpaper. The difference is it can be washed out.