Watco spray can lacquer clear finishing problems

[newuser1]

I've finished this pine duosonic body with Duplicolor spray cans and the finish came out really good. After drying for over 2 weeks I started applying Watco clear lacquer semi-gloss spray can finish yesterday and the result has these awful lines as if some of the finish hasn't dried fully yet.

The humidity was about 55% yesterday and I sprayed the guitar outside. Is that humidity trapped into my clear coats or is something else causing this problem?

 

[dsutton24]

It looks to me like you're spraying too dry, that is you're not getting enough finish on for it to flow out and level.

Is it actually wet to the touch? I've used a boatload of Watco lacquer with no trouble. It should be dry to a light touch within minutes.

 

[newuser1]

It looks to me like you're spraying too dry, that is you're not getting enough finish on for it to flow out and level.

Is it actually wet to the touch? I've used a boatload of Watco lacquer with no trouble. It should be dry to a light touch within minutes.

It is dry. Should I spray from closer, or just go slower?

 

[newuser1]

Anybody else willing to chime in?

 

[tewiq]

Hold your guitar body and use reflected light as a way to see the surface that your spraying .You need to see the shine as your spraying, that usually will be your best guide. I would try slower, but check the instructions on the can as to the distance that they recommend.

 

[stratisfied]

It looks like you haven't shaken your can enough and are getting different levels of semi-gloss. It also appears from the striping you have that you aren't applying an even coat.

 

[newuser1]

It looks like you haven't shaken your can enough and are getting different levels of semi-gloss. It also appears from the striping you have that you aren't applying an even coat.

I warmed the can for 30 minutes in hot water and I was shaking it for 2 minutes before application and every few passes while applying it, so that shouldn't be it.

 

[newuser1]

Do I have to sand down the uneven clear coats now or can I continue spraying on top of them hoping that it will fix it?

 

[Lowerleftcoast]

You can keep spraying.

Humidity/moisture usually ends up with a foggy or blotchy discoloring kind of effect.

I agree, it looks like it is not applied evenly. Use the advice of using the light to see the flow-out.

Too fast? Maybe.
Too far away? Maybe.
Not enough overlap on each pass? Maybe.

 

[snarf_nyc]

Could be mottling? its comes up if the metallic base is uneven and usually shows itself once you get clearcoat on. How many coats of sealer or primer did you use? and did you sand the sealer smooth before you shot the base? It kind of looks like the sealer/primer isn't even and it's making the metallic orientation look blotchy with stripes.

If you keep building clear coats, cut and buff it nicely, you might not even notice!

 

[Silverface]

After drying for over 2 weeks I started applying Watco clear lacquer semi-gloss spray can finish yesterday and the result has these awful lines as if some of the finish hasn't dried fully yet.

Why did you wait 2 weeks? Does the Duplicolor you used contain alkyd resin and mineral spirits (you should always read the MSDS to check)? If so it's a blend of lacquer an oil base enamel and could take a month for each coat to dry depending on thickness.

When I have had to use Duplicolor because a client requested a very specific color, I'd lay down 30-4 color coats (just enough to get smooth coverage and flow one day and do the clear coats and o(usually) buffing the second day.

If not and it's standard acrylic, nitrocellulose of a nitro/acrylic blend a properly applied coat dries in 30-60 minutes as long as the temp and humidity were OK. 55% is fine - over 60 is not. Lacquer does NOT cure over time - it dries ONLY by evaporation of the volatile components. And that happens within an hour at most UNLESS it's applied too heavily.

It doesn't look dry - it looks like the coats may have been too heavy and/or all applied in the same direction...or sprayed laying flat. All 3 of those methods will create lines, as you end up putting pressure on lacquer that's not dry and pressing it away from the center of the fan pattern.

Each "coat" should be made very lightly, using 3 light passes. A single coat should not cover or flow out smoothly like paint does. lacquer is a completely different animal. Coverage and flow do not happen until the 3rd or 4th coat.

We don't have any information about your "target's" position; spray direction; number of passes per coat (of everything you applied); and how light or heavy each coat was.

It is dry. Should I spray from closer, or just go slower?

Do I have to sand down the uneven clear coats now or can I continue spraying on top of them hoping that it will fix it?

You never, ever sand between clear coats or color coats.

Whose finishing procedure are you following? Your questions are all very basic procedural questions, and asking things that are "absolute" rules in lacquer application.

DO NOT SAND between coats to try to smooth things out. Sanding creates more problems than it solves, and lacquer is self-leveling IF applied correctly. NO sanding should be needed except to fix small runs - "finish sanding" before buffing is only done if mistakes were made and the whole system is uneven or has "waves" in it. But EVER between coats except after the sanding sealer applied first and again after paste wood filler, if applicable.

If you applied the color too thick you'll have problems with solvent entrapment - evaporative components unable to get out of the coating - which may "feel" dry - but unless each coat was very light it's not. You may be able to press a thumbnail into it and leave an impression, If so - it's too thick. And clear coats can re-wet pigments - in thick color coats the clear can push pigment to the sides or release the trapped solvents - either can create lines.

If ALL the color coats are too thick you'll have to remove them and start from scratch.

But if you were spraying with the body laying flat or partially propped up you have uneven thickness - it's always thicker close to you and thinner as the fan edge is further away. You need to always spray at a 90 degree angle to the piece, and always maintain a parallel "pass" - no "golf swings". And each coat should be at 90 degrees from the previous coat - "right to left" (or left to right), then turn the piece or nozzle on the tip so the next coat is across the previous one. And ALWAYS working from the top down, or you end up with overspray drifting onto what you just sprayed!

ALL of this should have been worked out and perfected when you practiced - prepared some scrap and applied the ENTIRE system on it - from sanding sealer, tinted paste wood filler, or pigmented primer, color coats, clear coats and buffing.

The practice runs should be repeated until you got the desired results, asked question if you had problems and learned how to "fix" minor errors. You shouldn't start work on the actual guitar runtil you know what you are doing.

And - no offense, I'm trying to help you - asking if you should spray closer, or go slower, are questions that come up at the very beginning of the practice runs.

Applying more color or clear over what you have - if you didn't practice using all the products first - will just make things worse. You *MAY* be ale to sand it completely smooth, apply pigmented primer over what's left, and proceed from there.

But you may have solvent entrapment if the coats were applied to full coverage. If so, full removal is the only solution - and then practice runs on scrap until you have your technique perfected with each product.

To really advise you properly we need to know (in each case the number of coats, direction of passes and time between coats):what primer was used, how it was applied and how it was sanded; how the color coats were applied, how the color coats were applied, and how many/in what direction the clear coat(s) were applied and WHEN the "awful lines" appeared.

 

[newuser1]

Could be mottling? its comes up if the metallic base is uneven and usually shows itself once you get clearcoat on. How many coats of sealer or primer did you use? and did you sand the sealer smooth before you shot the base? It kind of looks like the sealer/primer isn't even and it's making the metallic orientation look blotchy with stripes.

If you keep building clear coats, cut and buff it nicely, you might not even notice!

Why did you wait 2 weeks? Does the Duplicolor you used contain alkyd resin and mineral spirits (you should always read the MSDS to check)? If so it's a blend of lacquer an oil base enamel and could take a month for each coat to dry depending on thickness.

When I have had to use Duplicolor because a client requested a very specific color, I'd lay down 30-4 color coats (just enough to get smooth coverage and flow one day and do the clear coats and o(usually) buffing the second day.

If not and it's standard acrylic, nitrocellulose of a nitro/acrylic blend a properly applied coat dries in 30-60 minutes as long as the temp and humidity were OK. 55% is fine - over 60 is not. Lacquer does NOT cure over time - it dries ONLY by evaporation of the volatile components. And that happens within an hour at most UNLESS it's applied too heavily.

It doesn't look dry - it looks like the coats may have been too heavy and/or all applied in the same direction...or sprayed laying flat. All 3 of those methods will create lines, as you end up putting pressure on lacquer that's not dry and pressing it away from the center of the fan pattern.

Each "coat" should be made very lightly, using 3 light passes. A single coat should not cover or flow out smoothly like paint does. lacquer is a completely different animal. Coverage and flow do not happen until the 3rd or 4th coat.

We don't have any information about your "target's" position; spray direction; number of passes per coat (of everything you applied); and how light or heavy each coat was.


You never, ever sand between clear coats or color coats.

Whose finishing procedure are you following? Your questions are all very basic procedural questions, and asking things that are "absolute" rules in lacquer application.

DO NOT SAND between coats to try to smooth things out. Sanding creates more problems than it solves, and lacquer is self-leveling IF applied correctly. NO sanding should be needed except to fix small runs - "finish sanding" before buffing is only done if mistakes were made and the whole system is uneven or has "waves" in it. But EVER between coats except after the sanding sealer applied first and again after paste wood filler, if applicable.

If you applied the color too thick you'll have problems with solvent entrapment - evaporative components unable to get out of the coating - which may "feel" dry - but unless each coat was very light it's not. You may be able to press a thumbnail into it and leave an impression, If so - it's too thick. And clear coats can re-wet pigments - in thick color coats the clear can push pigment to the sides or release the trapped solvents - either can create lines.

If ALL the color coats are too thick you'll have to remove them and start from scratch.

But if you were spraying with the body laying flat or partially propped up you have uneven thickness - it's always thicker close to you and thinner as the fan edge is further away. You need to always spray at a 90 degree angle to the piece, and always maintain a parallel "pass" - no "golf swings". And each coat should be at 90 degrees from the previous coat - "right to left" (or left to right), then turn the piece or nozzle on the tip so the next coat is across the previous one. And ALWAYS working from the top down, or you end up with overspray drifting onto what you just sprayed!

ALL of this should have been worked out and perfected when you practiced - prepared some scrap and applied the ENTIRE system on it - from sanding sealer, tinted paste wood filler, or pigmented primer, color coats, clear coats and buffing.

The practice runs should be repeated until you got the desired results, asked question if you had problems and learned how to "fix" minor errors. You shouldn't start work on the actual guitar runtil you know what you are doing.

And - no offense, I'm trying to help you - asking if you should spray closer, or go slower, are questions that come up at the very beginning of the practice runs.

Applying more color or clear over what you have - if you didn't practice using all the products first - will just make things worse. You *MAY* be ale to sand it completely smooth, apply pigmented primer over what's left, and proceed from there.

But you may have solvent entrapment if the coats were applied to full coverage. If so, full removal is the only solution - and then practice runs on scrap until you have your technique perfected with each product.

To really advise you properly we need to know (in each case the number of coats, direction of passes and time between coats):what primer was used, how it was applied and how it was sanded; how the color coats were applied, how the color coats were applied, and how many/in what direction the clear coat(s) were applied and WHEN the "awful lines" appeared.

Fair enough, here is more info about the finishing I applied.

Here is the product description of the Duplicolor spray cans I used - it looks like it is acrylic lacquer:

Perfect Match® Premium Automotive Paint – Duplicolor

Detailed Product Information for Dupli-Color® Perfect Match® Premium Automotive Paint: get full product description and specifications, check out How-To Videos (as applicable) and see how other automotive enthusiasts have used Perfect Match® Premium Automotive Paint on their vehicles

www.duplicolor.com

I didn't use any sealer or primer. The only thing I sealed were knots (pine body) to make sure they get even color coverage. For that I used epoxy, which I have done successfully before and this time also worked great.

I've read in a book called Understanding Wood Finishing by Bob Flexner, that you don't have to use sanding sealers, and I quote:

"Products sold as "sanding sealers" don't seal the wood any better than the first coat of any finish. Sanding sealers just make sanding easier."

I did 6 color coats in total, and each one of them was very light, and I didn't start getting full coverage until the 4th coat. I have a home made spray stand, which looks like this:

Each coat I started with the sides of the body, while the body is parallel to the ground, then back (body is at 90 degrees to the ground), and then front (90 degrees to the ground). For the front and back I started at the top going down, from left to right and then right to left alternating, doing 50% overlaps. I sprayed at 90 degree angle starting spraying before the body and releasing the spray button after exiting. I never switched the cap spray pattern. I did all 6 coats in one day about 15-20 minutes apart. The finish came out absolutely great, with consistent coverage and shine, looking flawless. I spray outside when the conditions allow it, and use a small spray tent. The finish was looking absolutely dry in an hour after the last color coat, and after leaving it outside overnight even the smell of it was very, very faint. As I said the finish looked great. I left it for 2 weeks before the clear coat, simply because of lack of time combined with bad weather.

Before spraying the color coats I warmed up the cans for 30 minutes in hot water and was shaking the can regularly during application. I've done several bodies with Duplicolor Perfect Match and I know how to achieve a good finish with it now .

The Watco clear is another matter. I was using the same spraying technique described above, however I ended up with these uneven clear after 3 coats. Maybe I just need to continue in the same manner until I get better coverage?

 

[eallen]

While your quote from Bob Flexer may work on general wood working finishes those are generally not metalic solid color or guitar level finish qualities. You can use a standard coating to seal as long as there is no incompatibility but standard coatings are a fraction of the solids of sanding sealer as well as formulation differences to promote adhesion. Do to the lower solids of a standard finish product it takes multiple coats to equal a coat of sanding sealer. There is a reason production companies use sealers.

While it could be the picture it looks like the color coats have some color variation. It is a common practice by many including myself when spraying solid colors to start with a white base coat. The base coat color can change depending on the end effect desired. That allows any grain variations to be covered and provides a consistent color base for coverage of your color coat without grain variations showing thru.

It is quite hard from the photos for me to tell for sure what the finish texture or other issues you might be referring to.

 

[Silverface]

I've read in a book called Understanding Wood Finishing by Bob Flexner, that you don't have to use sanding sealers, and I quote:

"Products sold as "sanding sealers" don't seal the wood any better than the first coat of any finish. Sanding sealers just make sanding easier."

While your quote from Bob Flexer may work on general wood working finishes those are generally not metalic solid color or guitar level finish qualities.

My buddy @eallen is absolutely correct - except for the fact that Flexner is totally wrong!

This is a long post - but covers several topics that apply to this and other projects:

FWIW I worked in a paint/lacquer (which are NOT the same thing) lab for part of my 40 year career in coatings, where incoming raw materials were tested; formulations developed/tested, every batch of coatings tested, field inspection/testing was done if there were issues of certification of compliance were needed and so on...

Primers and sanding sealers were tested for penetration into wood surfaces, stain resistance (prevention of tannic acid bleed into topcoats for wood coatings)...

And critical sanding sealer tests were not only for penetration & adhesion (of both clear - for extended stain penetration time allowing color depth control by the applicator - and opaque types), but covered different types for use with different types of lacquer, water-based paint coatings, oil-based enamels, epoxies, polyurethanes, and industrial/military coatings you'd never encounter in retail or commercial paint stores.

=> Sanding sealers contain primarily different sizes/shapes of calcium carbonate and other pigments (yes, pigments can be "clear" OR colored) that the paint chemist/formulator selects in very specific ratios in order to *partially* fill the grain of a wide variety of wood. Sanding sealers - which are often also formulated to lock out tannic acid, light sap and other discoloring materials found in different woods - need to work on both lightly open-grain woods such as pine and mahogany to open-grain woods such as most types of ash.

Comparatively smaller pigment grains penetrate the grain more deeply; larger ones sit higher; "comparatively" is a key word, as with tighter grained wood medium-size particles only partially penetrate or don't penetrate at all, large particles sit on the surface held on my the sealer's resin (lacquer, acrylic, vinyl, alkyd etc) and as you go through wood types with progressively more open grain, the larger sizes penetrate.

When you sand the sanding sealer ( and you just need to sand lightly so the surface is smooth, assuming the stuff was applied properly in multiple light passes in crosshatched directions) the grain is partially "locked".

The clear types prevent stains & dyes from penetrating both quickly and deeply too fast for the average applicator to control (which is done by wiping areas that start to absorb and get darker or mottled and "pulling" the stain or dye out of those areas.).

Without clear sanding sealer, many stained or dyed wood surfaces look like an inconsistent, mottled mess that's difficult (sometimes impossible) to correct.

The pigmented types allow enough penetration of the color coats for good adhesion, yet prevent them from being sucked into the grain like a sponge.

If you DON'T use a sanding sealer...and especially if you apply full coverage coats...(because properly-applied lacquer is self-leveling) you'll have a very thin coating on the hard grain, a soaking-in of material in the soft/open areas and almost always some level of solvent entrapment in the open grain.

Always use sanding sealer (or a lacquer-compatible "stain preventative primer/sealer" on wood that commonly bleeds through coatings when applying an opaque finish (if you don't know which ones do, look them up!) - even if you don't think you need one!

I did all 6 coats in one day about 15-20 minutes apart.

That's DEFINITELY one of the problems.

In my opinion, Duplicolor's application instructions - even for their products - are wrong. They say "lacquer does not have a recoat window" and "you can reapply lacquer at any time". They use roughly the same solvents as other aerosol lacquers - and those solvents and other volatile contents MUST evaporate full from each coat before the next one is applied.

LACQUER DRIES ONLY BY EVAPORATION - THERE IS *NO* CURE TIME. THE SOLVENTS AND OTHER VOLATILE COMPONENTS MUST DRY BEFORE RECOATING OR THEY WILL BE TRAPPED AS THICKNESS BUILDS AND AS THE TOP SURFACE DRIES TO THE TOUCH.

Those solvents DON'T EVAPORATE "at any time" and will be trapped in the open-grain areas. The stuff may "feel" dry - but that's not how you test for dryness. Without inspection tools, you don't - which is why you apply LIGHT COATS an hour apart to be safe.

Another side note - Stewart MacDonald's "Guitar Finishing Step-by-Step" (written by Dan Erlewine) is another book that is is wrong - he repeatedly states that lacquer has a "cure time", which is incorrect unless it's a catalyzed lacquer that undergoes a chemical reaction. Conventional lacquers - even StewMac's Colortone - dries by EVAPORATION only. Also - that book ONLY applies to Colortone...and by coincidence, Deft...lacquers. "Four days is the minimum drying period before rubbing out" is wrong for conventional lacquer; most finishers I know buff the next day. And "The finish coat will cure after three to four days" and "After a week of curing..." are both absolutely incorrect - there IS NO CURE TIME, even for Colortone lacquers. Some need a longer DRY time for evaporation - but "cure time" for lacquers is one of the MOST common misconceptions in the DIY guitar finishing world.

Back to general lacquer usage - the ONLY time you coat "wet on wet" or even "wet on tacky" with lacquer is with the LAST clear coat, and only if you have enough experience to know EXACTLY how to time that coat so it's not too thick, won't run or cause orange peel, and can go right to the buffer after about an hour.

And that takes a LOT of practice time AND actual finishing.

I have applied quite a bit of Duplicolor lacquer when clients wanted their metallic lacquer colors (rather than special ordering expensive pints or quarts and adding to hazarous waste leftovers).

By the way - you are applying an acrylic/nitrocellulose blended lacquer. For those who have doubted this in the past - read Duplicolor's aerosol "acrylic lacquer" MSDS and look at the contents: one is "cellulose nitrate"!!

Yes, Duplicolor is a blend of acrylic and nitrocellulose resins - "acrylic" is NOT listed on the MSDS because it doesn't HAVE to be - it's not hazardous! Blends are common because 100% nitrocellulose lacquer dries to a very stiff film, and is far more subject to early cracking, checking and dings.

In my opinion and based on my experience with dozens of lacquer products, the application instructions are wrong for 99% of the lacquer products on the market and will likely result in solvent entrapment, lap marks, "alligatoring" and/or orange peel. NEVER use those instructions for another brand of lacquer, and I don't recommend it with Duplicolor.

Unless you apply VERY light, transparent coats of Duplicolor - the traditional light, non-flowing coat made up of three VERY light passes of any conventional lacquer - you will end up with higher mil thickness in the areas of overlap - ESPECIALLY if you did not spray in a crosshatch pattern, and worsened because softer grain areas have sucked primarily solvents into the wood due to the lack of a sanding sealer.

When applying clear coats you inevitably re-wet the surface (whether applying the next coat right or wrong), and in thicker areas some pigments like to "float" into the clear coats, as lacquer becomes simply ONE coat as each applied coat melts into the previous one. But you had inconsistent pigment reaction with the first couple of clear coats because of inconsistent mil thickness and insufficient drying of the color coats.

And if you applied full coverage coats instead of light coats, with coverage and flow starting at the third or fourth color coat you were applying it too thickly - i.e. like paint.

Lacquer ain't paint.

IMO you applied the color coats too thickly and did not allow enough dry time between coats. I recommend stripping it and applying a lacquer sanding sealer; then apply whatever lacquer you end up using in THIN coats made up of three almost "fog-like" passes (with full coverage and flow not starting until the third coat) - and at least an hour apart.

 

[Boreas]

If you want to try to salvage your project and not retreat, I would recommend laying the body flat when spraying to avoid runs from wetter coats. BUT I would make more passes with more overlap than what you were doing before. Keep speed the same. This should put down a wetter coat and help melt the layers below. Just do one coat this way and see what happens. Continue to warm/shake as you gave been. My feeling is it just needs a couple wetter coats. See if the streaks change or stay the same after this coat.

Worst case is you waste more nitro, but it may salvage the project. Just my $0.02.

 

[stratisfied]

I didn't use any sealer or primer.

View attachment 985062
View attachment 985063

There's your problem. Your wood grain is telegraphing through the paint as "shading".

People don't realize it but metallic colors are quite transparent. If you don't have a uniform color under it, you get shading. The darker grain against the white wood shows through as streaking. You need a solid primer under it. A little known fact is that a white primer will make a light metallic color brighter, a light gray will render an accurate color and a dark primer will create a more subdued color.

Primer your body with a white or light gray automotive primer (they are heavily pigmented for good coverage) and then recoat with color. The streaking will disappear.

 

[Silverface]

If you want to try to salvage your project and not retreat, I would recommend laying the body flat when spraying to avoid runs from wetter coats.

This applies the material at uneven mil thickness, - much thinner away from the tip and heavier closer. There are VERY few aerosol coatings that can be sprayed "sideways" - at a 90-degree angle to a flat surface.

And coats thick enough to run on a vertical surface are just as bad (if not worse_ on a flat surface, where fast drying lacquers can easily be applied too thick, skinning over and leading to solvent entrapment - and a coating system that never dries properly.

This technique generally creates overly thick "stripes" that trap solvents in the overlaps.

You never want to spray at an oblique angle unless you're applying a specialty coating mean to be sprayed that way. Only fillers stains, rubbed-on materials and brushed or rolled coating should be applied to a horizontal surface.

 

[trev333]

I'm totally wrong too..

I spray mine flat.. I get no "stripes" on metallics... with cans...
I never spray a vertical body.... I just hang them up to gas off....
must be doing something right..

I don't cut/polish either... or buff.... off the can finished...

they're guitars, not cars.....

hand sprinkled holo flakes too... with fingers....

 

[trev333]

how do you spray the roof of a car/truck body?.. turn it on it's side?....

 

[Boreas]

This applies the material at uneven mil thickness, - much thinner away from the tip and heavier closer. There are VERY few aerosol coatings that can be sprayed "sideways" - at a 90-degree angle to a flat surface.

And coats thick enough to run on a vertical surface are just as bad (if not worse_ on a flat surface, where fast drying lacquers can easily be applied too thick, skinning over and leading to solvent entrapment - and a coating system that never dries properly.

This technique generally creates overly thick "stripes" that trap solvents in the overlaps.

You never want to spray at an oblique angle unless you're applying a specialty coating mean to be sprayed that way. Only fillers stains, rubbed-on materials and brushed or rolled coating should be applied to a horizontal surface.

Trying to apply wet coats with rattlecans is obviously full of compromises. That's why pros don't use rattlecans. I can usually even out uneven application with additional coats of nitro, but a run or sag ruins my day. I am not saying this is the best way to finish a guitar body, but I am trying to save the OP the aggravation of starting from scratch.