Jump to content
ARC Discussion Forums
  • advertisement_alt
  • advertisement_alt
  • advertisement_alt
Sign in to follow this  
Devilleader501

lacquer Clear problem

Recommended Posts

I decaled an F-15 2 days ago and sprayed over the model tonight and the clear went opaque. I am wondering if it was because it was cold outside but the clear was warm. Because it was around 50 degrees outside I put the rattle can in the sink with warm water. Has anyone had this happen to them if so what if anything did you do to correct this. Im not mad about the model and I am sure someone I know will still want it the way it is Im just curious as to how this can be corrected in the future. The clear actually turned a milky color after it dried. Heres a few pics as to what I am talking about.

20150515_2120451_zpslcyqkicb.jpg

Share this post


Link to post
Share on other sites

Yes, it was the temperature. You may have warmed the rattle can, but the aerosol spray cools very rapidly due to adiabatic cooling (the drop in pressure as it leaves the can) evaporation of the propellant and solvent, and loss of heat to the cool air. Clear coats, gloss or otherwise, are particularly problematic in this regard. Fifty degrees is a bit cold for spray painting. Ideal conditions for spray painting are 65° to 75°F, 45 to 60% RH. The further you get from those conditions, the more likely you are to have problems. A spray booth is the best solution. Otherwise, wait for good weather.

If the cloudiness is due to frosting, you might be able to correct it with a light coat of clear gloss. If the cloudiness is due to entrapped moisture or solvent, that is less likely to help.

Share this post


Link to post
Share on other sites

Would it have been better to just spray the clear without warming it up first. 50 degrees was a number off the top of my head but may have been more around 60 degrees. I live in Arizona and we are having some really weird weather right now so a swing of 40 degrees in either direction overnight is nothing new. Building a spray booth may be my next project. I have been wanting to build one for some time now. Is there any certain clears you would recommend from the rattle can. The only clears I can get here are automotive and rattle can.

Share this post


Link to post
Share on other sites

Hard to say, but as you are in Arizona, entrapped moisture probably isn't the problem.

-

Automotive lacquers are probably better, especially if you buy quality, as opposed to the cheapest you can find.

A spray booth isn't merely a good investment—there is no negative aspect.

Share this post


Link to post
Share on other sites

You're welcome.

"A true expert is a humble man. He knows the extent of his own ignorance.";)/>

Share this post


Link to post
Share on other sites

Lacquer blushing. Google it for a better understanding.

Caused by the dew point and the ambient temperature being too near one another. Even if the ambient temp was 10 degrees above the dew point, the adiabatic cooling Triarius described above could drive the surface temp of the model below the dew point.

There's a possibility you might recover from it by simply spraying (lightly) some lacquer thinner over the area. Obviously, you should test this in a inconspicuous area first.

A paint booth will not solve the problem if it's installed in the same uncontrolled environment in which you cleared it in, unless it's heated and the subject to be painted is allowed to stabilize to the booth temp before spraying.

Edited by sluggo2u

Share this post


Link to post
Share on other sites

Yes, over spraying with Lacquer thinner will fix it.

I use Dull Cote Lacquer exclusively and have had this occur in the past, straight lacquer thinner from the airbrush will melt the frosted lacquer.

This is why I do not use acrylic clears, if something goes wrong you cannot correct them, but with lacquer you can always fix them using this method.

My typical flat cote method is to put Lacquer thinner in my cup, add the dull cote, not a real scientific ratio, but at least 50/50, as this cup empties I add more thinner, till I am spraying straight thinner on the last pass.

Curt

10_23_12.jpg

Edited by Netz

Share this post


Link to post
Share on other sites

A LOT of great points here. As I've stated many times before(for me anyway), "Triarius is the man when it comes to all things chemical." Triarius, I also like your quote about being humble. Too much pride gets a lot of people into a lot of trouble. True humility is a trait that is all too rare. A humble man knows when to drop back and punt. Anyway, enough rambling. Sluggo2u, you make a good point about temperature. "Ambient Temperature" is a non-specific phrase to describe the outdoor temperature. There are a lot of other aspects to ambient temperature, but basically it is the local temperature. For this reason, when the outdoor temperature is near the dew point, it will be humid and is often times a good "predictor" of rain in the near future. In my home state of Ohio, we have a saying about weather. "If you don't like the weather in Ohio, just wait 10 minutes." For that reason, I do a lot of airbrushing in my basement. I run a de-humidifier and use space-heaters when necessary to keep my humidity and temperature as near as possible to ideal painting conditions. Triarius have done a great job answering your questions. I simply wanted to chime in and let you know that it is best to paint under ideal conditions and it is possible to attain them yourself.

Share this post


Link to post
Share on other sites

Actually, you can fix some acrylic clears using a similar method, but use either 90+% isopropyl alcohol, or ethyl alcohol instead of lacquer thinner. I've done both with Future and Tamiya clears. May require a bit more finesse with an airbrush, since isopropyl evaporates more slowly than most lacquer thinners, and ethyl (or denatured) evaporates more rapidly.

Depending on the composition of the original "lacquer," these solvents may also work with non-acrylic lacquers.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...