High gloss polish on vanish

[TheFallen018]

Hi, I recently varnished a black surface with a high gloss varnish. After a few days I took a look at it, and noticed that the varnish, although it looked really good, it had left slight depressions on the surface where it had been sprayed on. I proceeded to sand it back with a wet sandpaper, working grades up from 1000 - 7000. After I finished, I proceeded to polish the surface, however it was unable to bring back the high gloss finish, and left the black looking lightly more grey than it should. Does anyone know how I can fix this?

[ian]

what was the underlying finish?
could it have been a shellac piano finish?

also 7000 seems fairly coarse for a really high gloss finish
I think normally you'd polish with something finer than 20,000

[TheFallen018]

what was the underlying finish?
could it have been a shellac piano finish?

also 7000 seems fairly coarse for a really high gloss finish
I think normally you'd polish with something finer than 20,000

I can't seem to find any grade 20,000 anywhere, but I've ordered a grade 15,000 for now. I'm also not quite sure what you mean by what underlying finish it was, but I know that I painted, and then varnished this piece from the bare wood. So what I'm sanding into is a normal oil based varnish.

[ian]

Hi Fallen

just to confirm
you have painted (sprayed?) a surface black
you have then sprayed over that surface with a clear high gloss varnish?

is it a varnish, a polyurethane, a catalysed lacquer, a pre-catalysed lacquer, nitro cellulose or ?
is it compatible with the underlying black finish

in terms of getting to a high gloss finish, you need a flat surface and to remove the all scratches from the previous abrasive.
is it possible that the underlying surface is not flat enough?

many people recommend using auto motive polishes to get a really high gloss surface


I'll defer to others but I'm wondering if what you are trying to achieve can only be done by polishing (without first cutting) the clear coat straight off the gun.

[router]

This is totally dependent of what you have put on, varnish, poly, precat lacquer,shellac?

If I want a high shine I cut the surface flat with wet and dry from 800 through to 1200 and then cut it back with G3 on rotary buff starting at about 800rpm and going up to about 1500rpm.

If you have an area or something else to try it on as a practice it would be good.

It works an absolute treat and you will finish with a mirror finish.

It all depends on what has been applied that you are trying to shine.

[Master Splinter]

If you're seeing a slightly different black, it sounds like you've sanded completely through the varnish layer and into the black finish.

I know if I want a high gloss finish I'll use car products, and typically:

Prime wood (car primer surfacer)
Lightly sand (300 grit- ish)
Spray paint - 3-5 coats, few minutes flash off between coats (nb stand can in 50 degree water for 10 mins beforehand to improve atomisation)
Leave to dry (overnight or next weekend)
Then either compound with car buffing compound, or cut back with 1200 or 1500 grit first if I've been a bit careless with the paint and then compound.

This is typically using the '4 spray cans for $10' enamel paint from Supercheap Auto, but I am meaning to try it with some of the Aldi enamel paint, as I picked up several tins marked down to $4 each.

[soundman]

Time after time we have people looking for a high gloss finish after the fact or using a finish product that simply is not appropriate or capable.

It realy must be understood that a high quality, high gloss finish, has to start with the very first stage of preparation...and any error in preparation or finishing at any stage will show up in the final finish.

It also must be understood that some products are simply incapable of producing the results some people are expecting.

spraying a coat of high gloss clear over an inadequately prepared surface will not result in a good finish....it will just show up every lump and bump in the surface.

I find the majority of time I simply do not have the time to do the meticulous preparation and pay the minute attention required to produce a good high gloss finish......so I avoid high gloss finishes if at all possible.

I have fairly well developed finishing skills ( certainly better than most hobbyists), and I have all the equipment and facilities short of a climate controlled spray booth........I do not believe a good high gloss finish is within the capacity of most hobbyists.

so.....for most of us we have to be content with a less than perfect high gloss finish......or to stick with satin or semigloss finishes.

now back to the original problems........we have a clear over colour....this realy is an advanced technique...and not of great advantage on black.

was the clear used compatable with the colour coat below?
was the clear a type of product that would resond well to rubbing out with fine abrasive?......if it was a polyeurathane.....the answer is no.......polyeurathane, simply does not polish at all well.

as has been mentioned......it may be the surface has been rubbed thru both the clear coat and part of the colour coat below.

It is most likley, that most of the imperfections where not in the clear top coat, but in the surface below.

if you want a good high gloss black finish......the product you need is a good quality black product.
AND..unless you have high skill and knowelledge levels, you are looking for a product that will give a fairly high gloss finish and will flow out straight off the gun......with maybe some rubbing out with compound.

Nitro laquer or acrillic laquer will do this well.......but not without good preparation.....for a quick and dirty, but fair gloss finish...ya cant go past QD automotive spraying enamel.


If there is one thing I know about it is spraying stuff black.........probably 60% of what I spray is black....very rarely gloss, for the reasons mentioned.

One trick with black is to deliberately stay away from 100% gloss.......every persentage point you move below 100% makes your job easier.......staying inn the upper end of semi gloss, can look convincingly glossy withoiut showing up every single piffling error you have made at every stage prior to the final coat.

cheers