Hi all
I'm using a brush to lacquer my new mahogany-veneered boxes, but I'm getting a lot of dips after the lacquer dries. I used 10% thinned lacquer for the first layer (as the instructions on the lacquer can say), and unthinned for the second layer. The first layer was completely absorbed by the veneer so I didn't sand it, but I sanded the second layer. For the third layer I used thinned lacquer again (more than 10% thinner) as someone on this board recommended, to allow the lacquer to even. But as it dried, dips started to appear. What am I doing wrong? Is the lacquer too thin, or what?
Thanks,
Mr. Push-Pull
I'm using a brush to lacquer my new mahogany-veneered boxes, but I'm getting a lot of dips after the lacquer dries. I used 10% thinned lacquer for the first layer (as the instructions on the lacquer can say), and unthinned for the second layer. The first layer was completely absorbed by the veneer so I didn't sand it, but I sanded the second layer. For the third layer I used thinned lacquer again (more than 10% thinner) as someone on this board recommended, to allow the lacquer to even. But as it dried, dips started to appear. What am I doing wrong? Is the lacquer too thin, or what?
Thanks,
Mr. Push-Pull
Attachments
How long did you leave between coats? Possibly not long enough. I think it was a mistake to thin the third coat as it seems to have reacted with the second unthinned coat.
What glue did you use to bond the veneer? Maybe there is some reaction with that?
Are you using the correct thinner? There's different types of laqcuer/paint systems - cellulose, acrylic etc.
What glue did you use to bond the veneer? Maybe there is some reaction with that?
Are you using the correct thinner? There's different types of laqcuer/paint systems - cellulose, acrylic etc.
There's not much you can do about the dips, its part of the wood/veneer your using. What your seeing is the laquer effectively shrink, something common with all solvent based paints, and reveal the imperfections.
You've got a couple of options:
Apply copious amount of laquer to effectively level the surface and then sand flat.
Fill the depressions but possibly make the veneer look terrible depending on the grain and pattern.
Live with the natural look and sacrifice the gloss finish.
You've got a couple of options:
Apply copious amount of laquer to effectively level the surface and then sand flat.
Fill the depressions but possibly make the veneer look terrible depending on the grain and pattern.
Live with the natural look and sacrifice the gloss finish.
I left the lacquer to dry for 2 or 3 days between the second and the third layer. It didn't stick to the sand paper so I assumed it had dried. The instructions say 24 hours drying time.richie00boy said:
I used PVA to bond the veneer.richie00boy said:
The istruction say to use thinner for alchidic paints/lacquers, and that's what I used.richie00boy said:
So the shrinking should be less severe with unthinned lacquer, right?ShinOBIWAN said:
In this case I think I'll try a fourth layer on the back of the box (unthinned) after sanding, and see what happens.ShinOBIWAN said:
mr_push_pull said:
Not really, thinning is just to make the laquer flow better on application and is mainly used for spray applications. The shrinkage is caused by the paint losing mass as the solvents are released during curing/hardening. Even a rather thick coat will shrink significantly after a month or two, revealing the depressions once again. Its the reason why joints reappear whilst painting MDF, that same thing will happen here. However, enough applications will see this effect lessened to the extent thats its invisible to all but the most concentrated examination.
pinkmouse said:
I agree, I've seen a similar effect when the surface (styrene in my case) had been contaminated by silicone mould release agent and I had neglected to clean the parts properly.
I think i would leave the job a couple of weeks to sit and see if it is going to react any more before I'd put any more layers of laquer on, then make a decision as to wether to sand back to the wood or carry on.
Lacquering - What am I doing wrong?
Hi Mr Push-Pull
What was on the veneer before you painted it? What kind of lacquer is it?
I paint a lot of things and in my experience, the only rewally successful way to paint/or lacquer things is to apply the stuff by spray - either from a spray can bought at hardwarte stores/paintshops, or by airbrush. A cheap airbrush (you'll still need a small compressor or at the very least a 12v tyre inflator - will not cost a lot. Here in Cape Town, airbrushes start at around 12 Euro to 'the sky is the limit. I have many spray guns and a few airbrushes, cvheap and expensive. In my opinion, a cheap airbrush comes within 95% of doing the same job as the expensive ones.
Mistakes people often make, is to apply too much pant or lacquer.
Easy does it. Rather 4 or 5 coats that 2 thick coats.
It looks like you will have to sand most of the lacquer off , before trying again.
Good lick
bulgin
Hi Mr Push-Pull
What was on the veneer before you painted it? What kind of lacquer is it?
I paint a lot of things and in my experience, the only rewally successful way to paint/or lacquer things is to apply the stuff by spray - either from a spray can bought at hardwarte stores/paintshops, or by airbrush. A cheap airbrush (you'll still need a small compressor or at the very least a 12v tyre inflator - will not cost a lot. Here in Cape Town, airbrushes start at around 12 Euro to 'the sky is the limit. I have many spray guns and a few airbrushes, cvheap and expensive. In my opinion, a cheap airbrush comes within 95% of doing the same job as the expensive ones.
Mistakes people often make, is to apply too much pant or lacquer.
Easy does it. Rather 4 or 5 coats that 2 thick coats.
It looks like you will have to sand most of the lacquer off , before trying again.
Good lick
bulgin
There are one of two things happening here... and I can't tell from the photo. Shin and Pinkmouse are right on the money here.
First, you could be just seeing little pits in the wood that need to be filled with lacquer... This is why you hear folklore about "40 coats of hand rubbed lacquer". If that is the case, keep coating and sanding to fill them up. As you apply more coats, sand more as you want to orevent to much build-up. Avoid thinner until you have filled the pits. The thinner is just soaking into the previous layers and making things spongy. Be sure to allow the final finish to dry several weeks before the final polish.
Second. you could be experiencing "fisheyes"... I think I see at least a few. Fisheyes are usually caused by oil. As you apply finish, the oil is driven from the surface and gathers up into the shape of small dots, and in these areas the laquer backs away leaving a perfect circular pit. These can be a nasty thing to deal with. Oil from skin, sweat and stain can cause these too. You know it's a fisheye if the surface is flat and the lacquer mysteriously forms a circular pit. There's a little drop of oil right in the middle of that pit. (Oil Stain = EVIL)
Always wash your surface before recoating. The best thing is freshly washed white tee shirts. Paper towels work too but leave lint. You need 2 rags, one wet, one dry. Use a mild solvent, like alcohol. Work a small area, use one rag to wet the surface, and immediately use the other rag to wipe the solvent off(do not allow the solvent to evaporate). Keep changing or turning the dry rag.
The one rag method is poor. Yes, you clean off some of the foreign matter, but the rest is just spread around very evenly. Two rags will get the gook up and off your workpiece.
Finally, if none of this works, and you know you have fisheyes, go to the paint store. There is some stuff called "fisheye preventer". It is uaually a little capsule of secret stuff that you add to your paint. An autobody paint store will have it too. It emulsifies the oil on the surface so it will mix with the lacquer and then, all is well.
First, you could be just seeing little pits in the wood that need to be filled with lacquer... This is why you hear folklore about "40 coats of hand rubbed lacquer". If that is the case, keep coating and sanding to fill them up. As you apply more coats, sand more as you want to orevent to much build-up. Avoid thinner until you have filled the pits. The thinner is just soaking into the previous layers and making things spongy. Be sure to allow the final finish to dry several weeks before the final polish.
Second. you could be experiencing "fisheyes"... I think I see at least a few. Fisheyes are usually caused by oil. As you apply finish, the oil is driven from the surface and gathers up into the shape of small dots, and in these areas the laquer backs away leaving a perfect circular pit. These can be a nasty thing to deal with. Oil from skin, sweat and stain can cause these too. You know it's a fisheye if the surface is flat and the lacquer mysteriously forms a circular pit. There's a little drop of oil right in the middle of that pit. (Oil Stain = EVIL)
Always wash your surface before recoating. The best thing is freshly washed white tee shirts. Paper towels work too but leave lint. You need 2 rags, one wet, one dry. Use a mild solvent, like alcohol. Work a small area, use one rag to wet the surface, and immediately use the other rag to wipe the solvent off(do not allow the solvent to evaporate). Keep changing or turning the dry rag.
The one rag method is poor. Yes, you clean off some of the foreign matter, but the rest is just spread around very evenly. Two rags will get the gook up and off your workpiece.
Finally, if none of this works, and you know you have fisheyes, go to the paint store. There is some stuff called "fisheye preventer". It is uaually a little capsule of secret stuff that you add to your paint. An autobody paint store will have it too. It emulsifies the oil on the surface so it will mix with the lacquer and then, all is well.
lufbramatt said:BTW pinkmouse, whats going on with the traffic in chatham? I was stuck outside chatham station for 25 mins earlier today, nightmare
Well, I can't blame the school run for once! That's usually what the problem is round there. They are ripping up the ring road round the town centre though, that may be the problem.
Fancy a pint sometime now you're back for the summer?
Looking at the picture, I would take an educated wag and say you had some contamination on the veneer. Normally if the holes are round, its due to solvent popping, shaking the lacquer and allowing air bubbles to get inside. These dips all appear to be irregularly formed and from what I could tell by the picture are randomly spaced. And I would suspect it to be a wax or soap used on the veneer cutting machine blade. Another thought is the moisture in the PVA may be trying to leach out. But my guess is a some on the veneer. How long after you glued was it before you lacquered?
mr_push_pull said:The only thing I can do is see what happens after a fourth unthinned layer, I think it can't be worse than this. All sides already have 2 layers of lacquer and this doesn't leave me with many options. Anyway, it doesn't look that bad from the distance
If you haven't done so I suggest using a sanding sealer after the initial sanding, prior to applying the first coat of finish. Doing so will help fill small pits and pores present in most hardwood veneers. Of course in order to do that now you'd have to sand off all the finish you've already applied and devise a system that would allow you to somehow suck the first coat out of the depth it has seeped to but that's a small detail
Seriously, one alternative to using a sanding sealer is to apply more coats of finish (5 or 6, maybe even 8) and to sand using a finer and finer grit as you go along, sand before applying each coat except for the last one. You can start with 80 grit and finish with 320 if you want perfection but usually using a grit finer than 220 is overkill because no one (but you) will be able to tell the difference.
In theory this should work fine. I say "in theory" because I have yet to succeed in producing a finish that could rival with, say, that of the ProAc Response Two or anything that has Sonus Faber written on it.
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