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View Full Version : best sealer, primer and lacquer



PV Audio
09-06-2005, 09:16 PM
whats the best u can get in all of the above for lacquering speaker cabinets? i'm sick of cheap *** sealers and primers screwing with my projects, so i need to know whats the good stuff to use.

:)

thylantyr
09-06-2005, 09:57 PM
I collected a bazillion recipes for finishing on top of MDF and it get confusing.
The bottom line is to use a high build primer for MDF and to prep the surface
smooth and planar if you want a high gloss reflective finish with less distortion.

I think you should look into automotive finishing products to get the uber results,
but that stuff cost more. It's good for show cars, good for speakers? /hehe

You can ask the folks here for specific brands;
http://www.carsound.com/cgi-bin/UBB_CGI/ultimatebb.cgi?ubb=forum;f=4

If you don't want the show car finish then you can use simple and cheap recipes
that aren't too bad and can give you good results, but not show car quality.

This finish was such a recipe, you can see the gloss reflection but you see the
distorted image, not mirror like.
http://home.pacbell.net/lordpk/robarray/11.jpg

This recipe was;

Zinsser BIN spray primer, $5 a can. A few coats to build up. Sand between coats,
or use judgement as the first or second coat may not need sanding depending
on how thick you layed it on. Ideally, spray thin coats even though the spray is
thicker. Try to spray from a distance and spray fast.

During this phase I noticed BIN isn't a sandable primer but goes on thicker
than $4 gray automotive primer, so when I tried to sand it with an orbital sander,
the primer sticks to the sand paper, these sticky particles were like fine grains
of sand and when the paper clogged, it re-scratched the surface -- arg. Sometimes it make big scratches on areas that I sprayed on too thick. So watch out.

I used an air compressor while sanding to blow away these particles. For smaller
speakers, not giant towers, you can manage easy and just be careful when
sanding, I think I used 320 grit. If you do it right, there is a baby butt smooth
finish, it feels good :)

For sanity check, I used some gray primer as the final top coat to double check
for defects left behind on the BIN primer since it's dark, I can more more defects
and I applied a few coats, maybe two or three. It goes on thinner than BIN and
sands well. I was able to get a nice polish with this gray primer on top of BIN.

The other reason for using it was. I embeded magnets in the MDF and did a Bondo layer. This was a pain to get right and I can still see the magnet imprints,
the gray primer revealed this better than the white BIN primer. You can skip
the gray primer stage if you feel good about what you did.

The final step was to use spray can paint, gloss black. This is the parts that really
suxs. Dust particles kick your butt and ruin a nice paint job. Clean up the garage,
blow it out with compressed air, wait hours to let the dust settle and mop the
floor wet and keep it wet when painting so dust doesn't kick up when painting.

I found some cool paint, Rustoleum Professional paint, cost a dollar more and
comes in a bigger 15 oz can. I did tests, this paint dries hella fast. I painted two
piece of wood using this paint and regular Rustoleum and the Pro paint dried much faster and because it did, less particles of dust settled on the sample.
I repeated the test to verify results, the Pro paint owned for a dollar more.

You can do three coats, wait 1 hour between coat, lay a nice stream, but not too
thick on the edges as it runs. Lets it dry for a few days before handing.

The MDF edges sux bad. Before I did all this, I used Minwax sanding sealer on
the edges and that absorbed so much sealer that it took ten coats to fill those
edges and because there was so many coats, some of the sealers leaked to
the front baffle and created high spots which needed sanding off. /not sweet.
If I were to do it again, I would tape off the front baffle before sealing edges.
I might try a thick sealer next time. Some people mix yellow wood glue with
water, 50/50 mix to seal edges.

///

If you want non MDF recipes, then there is a bazllion of them too. Those speakers
I made were oak plywood with stain, then two coats of thin wipe on polyurethane. I spent weeks trying so many recipes on tons of sample pieces and
nothing satisfied. Here is the deal with oak, it's got big pores that need filling and
if you want a thick top coat that looks nice you need to fill those pores OR ignore
the pores and use a thin coat instead. It's a personal preference. Pores + thick
finish looks poor. Pores + thin finish looks better, the lesser of the two evils.

If you must fill those pores, I have some esoteric recipes that involves acetone
based wood filler mixed with more acetone to make a mud. This mud is layed
on the wood to fill the pores and you make a 'squeegee' out of a wood block
wrapped in an cloth rag soaked in acetone to scrape the mud off, but hopelly
not pull the mud out of the pores. Do two magic mud coats. If you want to be
clever, mix some stain with magic mud.

There is another way that sorta works, but I didn't have great results. You use
a gel stain as it goes on thick to fill the pores, but as you apply gel and gel and gel, the dang wood gets darker and darker and darker. catch 22.

If you use wood with little or no pores, then the job is easier. Stain it. /done.

A simple wipe on poly is fine. I have a more complex lacquer recipe I got
from this man.

http://members.shaw.ca/lcleven/home_page1.html

Bottom line. Experiment on scraps first.

Tips
Polyurethane is polyurethane no matter what brand youo get. The difference is
vicosity. Minwax brands are 'thinner' which actually has advantages to make it easy to apply. Thicker poly is like a Parks Pro brand, goes on thick, may or may
not be desirable depending on what you do. Wipe on poly seems to be the same
as any other poly, they just charge more, maybe it's thinner?

Varnish - Typically is thick and you need to thin it.

Shellac - Interesting stuff, but the common stuff in store contains wax which
is not good as a base for other top coats.

You sorta have to buy all these products and just do some tests to see what
you can do with it.

PV Audio
09-06-2005, 10:23 PM
my friend you are a life saver

thanks ALOT

:)

PV Audio
09-06-2005, 10:26 PM
yo, is that professional paint a lacquer? or an enamel...

either way, u got pics of the finish? thanks