I'm pretty sure Goof off is what our partners believe we're doing when we say we're building guitars ... :D
Peter
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I'm pretty sure Goof off is what our partners believe we're doing when we say we're building guitars ... :D
Peter
This is getting along, but I'm having a hard time getting the poly as shiny as I want, partly because I don't actually know what I'm doing :p
https://i.ibb.co/FH75JrP/20220518-113535.jpg
You can see in the photo there are what I would describe as little divets all over the surface, so even though the flat bits are quite shiny it still doesn't look like a mirror. The photo is probably one of the worse bits, there were a few patches that I actually did get really smooth. Can I have some tips for getting this smoother?
I have wet sanded with 1500 and 2000 and used car polish, but I'm not really sure what to do next.
How are you applying the poly? Wiping or spraying?
This may be a silly question, is that a satin poly?
It looks like satin to me. If that's the case, it will polish, but won't look the same as a true gloss poly no matter how much it's buffed.
I'm wiping. Yes it's satin, I figured that it won't quite look the same as a gloss, but I've seen that I can get some of it to some degree of shiny that's better than having those little pock marks in it, so I was hoping there was a way to still get it all at least smooth.
Okay so... re: the dimples, the only way to get rid of those is by level sanding with a coarser grit paper before moving on to the finer 1500 & 2000. You just need to be careful not to sand through or you end up with a whole other set of problems.Quote:
Originally Posted by jarro_2783
Since you're wiping on, it looks to me like they may have been caused by possibly wiping on a new coat before the previous one was cured enough or the rag touch the surface before the newest coat whilst it was still tacky. That's purely speculation on my part, but satin poly is usually much more forgiving than gloss, so something happened there.
It needs to be treated just like "orange peel" that occurs with spraying.
re: polishing satin poly, the reason satin poly doesn't "shine" like gloss poly is because is has solids mixed in to it that diffuse light when it tries to reflect off of it (that is a very generalised explanation). I typically don't even sand satin poly unless I have to fix a defect (like an effing bug lands on it!). If i do need to sand for any reason, I just do what needs doing and then apply a fresh coat or coats until I get as near perfect as I can get it. Sometimes this means a few extra coats, but it's worth the time IMO.
If there's one step in guitar building that takes time and shouldn't be rushed, it's the finishing process.
I was afraid the answer was going to be more sanding :(
I find my sandpaper gets gummed up with poly quickly, so I could wet sand with 800, but I'm not sure if that would be the right approach at this point.
It's possible that I added more layers too fast, I was doing about 3 a day because it dries so fast. But also the veneer was not completely flat, so the bumps could just be from bumps in the veneer.
That's a sure sign that the poly is not fully set. Depending on how many coats have been applied, how much they were allowed to "dry" between coats, ambient temperature and humidity etc... you may need to leave it for at least 4 weeks before sanding at all.Quote:
I find my sandpaper gets gummed up with poly quickly...
As I said before, finishing is not a race or an easy task for the impatient. (and I definitely fall into that category!)
I didn't realise it needed so long, I think I'll just let it sit for a while then.
When I say gummed up, it's not like it's wet, but the dust just sticks to the sandpaper really quickly. Will it not do that once it is set better?
After I let it dry, do you have a recommendation for where to start with the sanding? Would you go all the way back to 240 and just be careful to not go through just to get those small bumps out?
It's called "corning" and it can still happen with dry sanding even when it's cured, but it shouldn't happen straight away.Quote:
When I say gummed up, it's not like it's wet, but the dust just sticks to the sandpaper really quickly. Will it not do that once it is set better?
If there are significant bumps or debris, maybe start with P400. If it's reasonable smooth you may get by with P600.Quote:
After I let it dry, do you have a recommendation for where to start with the sanding? Would you go all the way back to 240 and just be careful to not go through just to get those small bumps out?
Also if you have any drips, runs to debris in spots but the area around them is good, you can use a method called strip sanding to fix the defects then regular flat sanding after that.
Strip Sanding
Thanks, that's very helpful. I'll leave it for a couple of weeks and see how I go.
I do have some runs, so I'll see if that helps get them out too.