Unwanted texture, help!

[I’ve got wood worm!]

Hi all.
I am being offered the ongoing commission of finisher to a luxury range of acacia wood handbags. The company is Rocio, check them out they do some really interesting designs!

The half shells are coming to me rough and with some machining defects and ridges, straight from CNC machining (I presume) in the Philippines. They are made from Acacia sleepers.
The company wants me to quote them for the sanding down and application of spray lacquer.
I sanded the test shell down using 180 and then 240 grit. Then applied 3 coats of spray lacquer to one side. After leaving to full cure strength, ill flip them over and spray the inside.
Upon inspection this morning, I can see/feel lots of texture in the surface from the pores in the wood. I personally don’t mind this look and feel but as a luxury brand and judging from the thick looking, high sheen appearance of their other products, I don’t want this to be a reason to lose the ongoing commission.

Here are a few pictures to try and explain my challenges:

Retrospectively, maybe I was naive in using only 240 grit and have since sanded it using 1500 grit and reapplied the spray lacquer. I’ll be interested to see how this dries.

Can anyone give me any advice on how to combat this? Is the choice of spray lacquer wrong? Do I need a thicker brush on varnish or something? (Finishing is not really my stronghold) I believe my technique to be fine, never had a problem before and make sure to overlap sprays and not be too heavy or too light etc. Am I not sanding it enough?
I don’t want to elongate the process too much and it may be prohibitively expensive for them (even though this one will probably retail for £675!)

Any advice is greatly appreciated, thanks.
Dave.

 

[Droogs]

Firstly sand to 320g
Clean off then build up very thin coats of shellac
Use golden/blonde
Give each coat time to dry fully and sand with 320 followed by 400 once you have built up a smooth even coat
Leave to fully cure then de nibb
Now build up your laquer in fine mist coats x3 then apply a couple of normal coats
Leave to fully cure and polish with autosol


Or cover in liquid glass. Less steps just as much work

Hth

 

[Droogs]

If you are going to be doing this often then invest in a paint oven system for your spray booth this will get the full process down to around 3 days for each batch rather than around a week. And you want to do these in batches or you'll soon be well peeved that you took the job on as they will be a lot of FAFF individually

 

[I’ve got wood worm!]

Interesting! Thanks for the replies.
This sounds like a right PITA if I'm honest, not sure I want the job now!
I have a relatively small workshop, working out of a single car garage and am mostly tooled up for joinery and the rougher side of woodworking, not really a finishing house.

They were pressing for time so I have submitted a project proposal report with the amended finish, though the texture was reduced slightly after sanding with 1500 grit and applying a 4th lacquer coat, it still suffered from this problem.
Droogs' advice sounds like the technique that they're probably after, but I don't think that they will accept the subsequent costs from a lengthier process... I watched a couple of youtube videos from guys that were using this exact technique and the finish was great, though it's not up my street at the moment. We'll see that they say, I'm not expecting much though!

Thanks again.
Dave.

 

[Sgian Dubh]

They were pressing for time so I have submitted a project proposal report with the amended finish, though the texture was reduced slightly after sanding with 1500 grit and applying a 4th lacquer coat, it still suffered from this problem.
Dave.

You don't say what lacquer you're using, but presumably it's something like pre-cat or acid cat lacquer. My first observation is that, in my opinion, you're oversanding. There's really no good reason to go finer than about 180 or 220 grit prior to spray polishing. The wood is a coarse grained species, hence the visible pores and relatively rough texture, so the solution is to fill the grain to create a smooth surface and there are different ways to achieve that. An efficient method is to use a grain filler, such as this stuff from Jenkins, or much the same type from Morrells; there are other suppliers. You just have to pick the right colour from the range available, but generally you usually go for stuff that's a shade darker than the wood you're filling, although contrasting colours, even bright ones, can be used if that's the look you want. Because your wood has distinctive light and dark bands, you might consider using a transparent grain filler.

Grain filling can be done prior to the application of any finish, or it can be done after a first light'ish coat of polish. The second option helps preserve the colour of the surrounding wood better because the polish creates a barrier between the grain filler and the dyes and pigments it contains meaning they, along with the binder, lodge in the pores, but those colourants don't affect the wood surrounding the pores. In which order you undertake the processes is down to the look you require, so it's obviously best to establish the procedure on some practice pieces prior to pricing up the job. Slainte.

 

[MikeG.]

It might be worth your while popping a version of this thread into the turning sub-forum, because these odd timbers and finishing issues are everyday stuff for them. I doubt you'll get a better answer than Richard has just given you, but there will be people who have turned acacia.

My only experience with acacia is having the thorns go through my tyres in Africa, so I can't help directly.

 

[Cabinetman]

I’m with Richard as well, it’s not often I want to glassy finish, many years ago I made a couple of interior oak doors that required that sort of finish and I filled the grain with putty which was time-consuming and messy and probably not the right thing to do but it worked fine I then French polished them.

Hell those must be some thorns! I’m guessing you could almost use them as nails.

 

[MikeG.]

.....Hell those must be some thorns!.......

They can be up to 6 inches long, and baked iron hard. Never drive over elephant dung, because elephants eat acacia but don't digest the thorns, meaning their pooh is full of it, and held up at appropriate angles for tyre penetration by the mixture they're embedded in. Think blackthorn's big brother, and twice as strong and hard.

 

[Cabinetman]

The things you learn on here ha ha. No I’ll remember that and I won’t drive over any elephant dung on my way home! It doesn’t bear thinking about what it does it do to their intestines.

 

[profchris]

Lacquer keeps shrinking, so even if you spray enough to sand level, the pores will reappear a few weeks later. If you repeat the process then you might be lucky second time around (or need a third go).

Pore filling is the answer. Even then, a high gloss finish is a lot of work, it shows even the smallest imperfection.

 

[Ttrees]

I wonder if pumice would work for this, or if the pores might be too large?
I have very little knowledge on finishes, but from looking at these results, it looks a whole lot nicer than a epoxy pore fill.
This video gives an impression on what pumice looks like

 

[doctor Bob]

They can be up to 6 inches long, and baked iron hard. Never drive over elephant dung, because elephants eat acacia but don't digest the thorns, meaning their pooh is full of it, and held up at appropriate angles for tyre penetration by the mixture they're embedded in. Think blackthorn's big brother, and twice as strong and hard.

Now you have me worried ........... what if it's not horse poo but elephant poo on my gravel track!!!!

 

[clogs]

it's easy to find Acacia in France below the Loire valley and further south in Europe......
very nasty, have you seen the butcher bird use them......

Acacia is the preferred wood for the vineyard posts then oak......
Acacia lasts up to 50 years I was told.....oakis anything upto 10 years.....where I lived.....
Almost as bad is wild Almond.....

 

[MikeG.]

..........It doesn’t bear thinking about what it does it do to their intestines.

Absolutely nothing at all. It's just about their favourite food, and their tongues, throats, stomach, guts, and bowels are much tougher than boot leather.

 

[Cabinetman]

Hell like eating Barbedwire.
T trees, I’d forgotten all about pumise, I got all my dad’s old woodworker annuals out many years ago and taught myself to French polish from them, I seem to remember they called the pumice bag a "ponce bag" I don’t know why it is but I never trust Americans showing us how to do things on YouTube – actually there is one exception, come back to him later. Probably because they talk too much.

 

[profchris]

I've recently tried pore filling with pumice. Not the proper french polishing version but my own lazy adaptation.

1. Two or three coats of shellac allowed to dry.

2. Sprinkle a little pumice on the work.

3. Moisten a pad with dilute shellac, rub away in a circular motion.

4. Gently sand level when dry.

The back of a ukulele takes only 2 or 3 mins to do, and I can repeat after an hour or so.

it works nicely on mahogany, but a truly full gloss would need 4 or 5 applications.

 

[Cabinetman]

So Profchris, do you think it would work? Personally and I’m sorry to say this, I think the company is looking for a cheap way out of a difficult problem.
So "I’ve got woodworm, " unless you have managed to find (through us all) a way to finish their handbags in an economical way I wouldn’t go signing any contracts in the near future.
Some of these companies employ pretty low level people who get themselves into a bind and are desperate to pass the buck. Read that contract carefully you don’t want to be stuck with the cost of all those duff handbags. Ian

 

[johnnyb]

polyurethane 2k lacquer is what's needed on this type of stuff. like rolls Royce dashboards! plenty of buffing with mops as well.. it's a strange product not really shrinky like lacquer. try it but it's a bit poisonous.

 

[I’ve got wood worm!]

You don't say what lacquer you're using, but presumably it's something like pre-cat or acid cat lacquer. My first observation is that, in my opinion, you're oversanding. There's really no good reason to go finer than about 180 or 220 grit prior to spray polishing. The wood is a coarse grained species, hence the visible pores and relatively rough texture, so the solution is to fill the grain to create a smooth surface and there are different ways to achieve that. An efficient method is to use a grain filler, such as this stuff from Jenkins, or much the same type from Morrells; there are other suppliers. You just have to pick the right colour from the range available, but generally you usually go for stuff that's a shade darker than the wood you're filling, although contrasting colours, even bright ones, can be used if that's the look you want. Because your wood has distinctive light and dark bands, you might consider using a transparent grain filler.

Grain filling can be done prior to the application of any finish, or it can be done after a first light'ish coat of polish. The second option helps preserve the colour of the surrounding wood better because the polish creates a barrier between the grain filler and the dyes and pigments it contains meaning they, along with the binder, lodge in the pores, but those colourants don't affect the wood surrounding the pores. In which order you undertake the processes is down to the look you require, so it's obviously best to establish the procedure on some practice pieces prior to pricing up the job. Slainte.

Sounds like a workable technique. Thanks Sgian! I’ll look into the fillers and work it into my cost estimate.

 

[I’ve got wood worm!]

Lacquer keeps shrinking, so even if you spray enough to sand level, the pores will reappear a few weeks later. If you repeat the process then you might be lucky second time around (or need a third go).

Pore filling is the answer. Even then, a high gloss finish is a lot of work, it shows even the smallest imperfection.

Yeah, thanks. That’s what I worry about. Aiming for such a high quality perfect finish is perhaps not in my gamut. I’ve got too much regular woodwork on to become a master finisher unfortunately.