Mohawk Blush Retarder-any time limit?

[Lou Tencodpees]

I ran into some lacquer blushing while clear coating my current project. After some research I decided to try out Mohawk Blush Retarder. I gave it a couple days but it didn't go away. It'll probably be a week before I receive it. Never having used it before I'm curious if its effective after that much time. I understand its best to go very light and sparingly to avoid running.

Appreciate any insights.

 

[Freeman Keller]

My one experience with blushing was my own fault, I sprayed in too high off humidity. I tried the Behlen blush eraser and it did not correct the problem. After a couple of years of being bugged by the finish I stripped to bare wood and started over.

 

[dogmeat]

I don't know that particular one but retarder is generally mixed in as part of the reducer before you spray. it is a slower drying solvent. the evaporation of the carrier solvents causes a lowering of temperature. the quicker it flashes off, the greater the temp drop. if the dew point is close to ambient temperature then moisture starts condensing out

 

[photondev2]

I have used it successfully to fix blushing issues. I only use Mohawk lacquer. It didn't take long to work. I made sure it was a warm day with low humidity.

 

[old wrench]

It will melt new lacquer or old lacquer

Definitely ease into it with very light sprays until you see how it acts - it's possible to melt all the way through as many lacquer coats as you might have applied


.

 

[Lou Tencodpees]

I have used it successfully to fix blushing issues. I only use Mohawk lacquer. It didn't take long to work. I made sure it was a warm day with low humidity.

Yep, using Mohawk rattle cans. I switched to their Ultra Flo clear for the final coats, that's when I ran into the blushing issue. Being in Texas low humidity/warm days can be far and few in between, but point taken.

 

[Sea Devil]

I've never had more than brief episodes of light blushing that vanished within minutes. I've used the blush retarder to manipulate dry time, increase leveling, blend the edges of spot repairs (Mohawk makes another product specifically for that, but I haven't tried it) and to make ancient, flaking finishes lie down so that they can be clear-coated. It will "re-wet" any lacquer finish, no matter how old. But it also seems to starve a finish of plasticizers, rendering it more brittle. That's why products like Qualrenu amalgamator exist, but amalgamators completely screw up the surface and turn it into a gooey soup. That said, amalgamator applied with an sensitive touch can do miraculous things. I've actually used it on shoes to revive cracked and heavily creased topcoats!

In spite of your bad experience with the Ultra-Flo, I'm intrigued by it. I use Mohawk products a lot and find them to be reliable and easy to control. The Ultra-Flo sounds like a great product under the right conditions.

 

[stratisfied]

I use the Ultraflow both for touchup and full finishes. Never experienced blushing. It flows out so well you can even do airbrush spot touchup sprays on polyurethane and polyester finishes with near perfect blends. On a new finish, you can bypass the wet-sanding and it just buffs like glass.

Here a top I did spot repairs, a partial re-burst and full overspray. No wet-sanding. Sprayed and buffed.

 

[Lou Tencodpees]

The Ultra-Flo sounds like a great product under the right conditions.

Yeah, I am positive the fault is my own and not the product. I think I went on too heavy during non-optimal humidity.

 

[Sea Devil]

stratisfied, that looks fantastic! I'll have to try it out. My local store carries it.

 

[old wrench]

Yeah, I am positive the fault is my own and not the product. I think I went on too heavy during non-optimal humidity.

That is how blushing always seems to happen - too heavy of a coat

It's part of the learning curve for spraying lacquer.

Most of us are used to using rattle-can "spray paint" which is very forgiving and hard to mess up with no matter how you spray it on - lacquer requires a lighter touch


.

 

[stratisfied]

stratisfied, that looks fantastic! I'll have to try it out. My local store carries it.

Thanks!

I think you’ll like the Ultraflow.

 

[Silverface]

I understand its best to go very light and sparingly to avoid running.

NEVER spray blush eraser/remover etc. directly on the surface! You will overload the surface with solvent and end up with a runny mess.

Mist it at least 18-24" above the surface and mist it at a 90-degree angle. letting it drift down onto the problem area. Mohawk/Behlens (same thing) and other anti-blush products are slower-drying solvent blends with a small amount of lacquer resin (nitro or acrylic - doesn't matter, they are compatible with each other - many lacquers are nitro/acrylic blends.).

Blush is simply trapped moisture resulting from spraying coats too thick or when the humidity was over the manufacturers' specifications. Usually it's a combination of problems - since lacquers do NOT cure and dry only by evaporation, keeping each coat thin - especially in marginal conditions - is absolutely critical. Each coat should be VERY thin and consist of 3 very. very light passes; a single coat doesn't flow together - "flow" and coverage doesn't occur until the 3rd or 4th coat.

NEVER spray lacquer like you would spray paint!

As an example, I've been doing finishing work for 50 years and live in Southern California, where conditions are generally more favorable. But this year was typical - from around November 1 until now Dec 10) I've had about 6 days of favorable "open garage" spray conditions (in a garage with no gas water heater - even with an open door spraying with one in the area is literally playing with fire.).

I used to have a booth, explosion proof/hard-wired fans and dehumidifiers when i was spraying daily, but now i just do my own stuff and a few favor jobs. But now I check the temp/humidity daily several times and only spray when I can. I was also in the coatings business for decades (this stuff was side gig) and understood measuring coating thickness to the point where I could do it by feel. Usually.

But done right - and with conventional lacquers, not lacquer enamel blends like Colortone and Deft - I could spray a guitar in 2-3 days (not including fillers if needed), buff it out the next day (no finish sanding - that's done only if there are problems) and it'd be good to go.

If you get blush after several days it's a strong indication that one or more coats were too thick, even if sprayed in just-below-the-limit conditions. Blush will occur immediately or within 12 hours or so if the coats are proper thickness.

Hope that's helpful.

 

[Sea Devil]

I've found that if you mist a little blush remover on, you can add more multiple times at about ten-minute intervals and it only makes the finish gummy; it doesn't pool and won't sag if it's horizontal. In other words, you can use quite a bit of it if it's applied gradually. I once did about six passes, and it was mostly set about two and a half hours later. I wasn't trying to remove blush, just trying to level things out a bit without adding or removing material.

If you use too much, it can create cracks in much the way that spraying straight thinner can. That's what I meant by starving the finish of solids/plasticizers. Thin coats over fat can shrink the surface faster than what's undeneath; that's what creates cracking. I've had good results shooting some retarder first and hitting it with a fast-drying clear while the substrate was still wet, but I don't recommend trying that on your guitar. You should never try anything for the first time on the actual piece you're finishing if you can avoid it.

Do try things like that on scrap. You can see the surface moving if you have good enough lights. Lacquer is very volatile, fast-drying stuff, and it's fascinating to observe how it behaves. Of course, sticking your face inches away from it right after spraying isn't good for you, so wear protective gear. (I should say, keep it on... you should already have it on even for short bursts.)

 

[Sea Devil]

BTW, "thin" and "fat" in the above post refer to ratio of solvents to solids, not the thickness of the application.

 

[eallen]

I have had times when sprayed on blush remover won't take care of it that scuff sanding with 800 grit to break the hardened surface followed by reapplying the remover has then worked.

I have have been times when scuff sanding alone has remedied it after a day setting when blush remover wasnt available.

Eric

 

[Sea Devil]

It kind of soaks in from the top down and saturates the surface easily if you put too much on at first.

 

[Willie Johnson]

Just use appropriate protective equipment, or you'll go from this:

to this:

 

[Lou Tencodpees]

I am going to assume spraying blush remover should also be done in optimal conditions (low humidity)?

 

[Sea Devil]

I was terrified of overdoing it the first time. I had visions of the finish turning into greasy snot and just sliding off. It will work its way down a bit if you watch the surface and just add as much as it's willing to absorb. It's like watering dry dirt.