Removing excess enamel wash is removing underlying acrylic layers too and I don't know why

I had the same experience years ago: I painted with Tamiya acrylics; a week later I gave it a coat of future, decalled two days after that; gave it another coat of future the next night; then let that dry for two more days. I had read somewhere that enamel washes were superior to others, so I made a wash using Model Master paint with Testors' enamel thinner, which then proceeded to strip paint away. It didn't do it everywhere: mostly, I noticed, in places where it had pooled. The paint and clear coats came off when I disturbed it with my brush trying to remove the excess. 

I though it would be safe to use over an acrylic coat, but obviously this wash hadn't read the hobby magazines. I stopped using it and went to mineral spirits, and I've been suspicious of any kind of enamel wash, home-made or commercial, ever since.

Thanks Greg!

You should be proud of that, it looks good.

High scores for perseverance.

Thank you all for your feedback and advice. I managed to complete the Spitfire so I thought I'd post a photo. There are lots of areas where I can improve but I'm pleased with the result, especially since it's been over 40 years since I completed the last one!

I have two other kits on the go (Airfix 1:32 WW1 B Type Bus and a Mr. Hobby 1956 VW Beetle) and will put your advice to good use. I did minimal weathering on the Spitfire but the WW1 bus will see its fair share of Flanders mud.

Thanks again!

oldermodelguy

 

 

JohnnyK

I find that Testors' enamel thinner also removes Testors' Metalizer paints, eventhough the paints are lacquer paints.

 

 

 

 

Ya, not too handy for cleaning up pin washes !

 

JohnnyK

I find that Testors' enamel thinner also removes Testors' Metalizer paints, eventhough the paints are lacquer paints.

 

Ya, not too handy for cleaning up pin washes !

Jon_a_its

I can't comment about curing times, as I build so slow my club nickname is glacier!

I have noted in my own use of a dozen types of paint, some are considerably more sensitive to handling.

In my use (your milage may vary) Hataka def. needs a good primer (badger Stynylres or Halfords rattle-can),  with Tamiya & MIG being the most durable to handling.

All paints need time to cure fully, so if, as above, the coats closest to the plastic aren't cured, they can delaminate, with Valejo Polyurethane primers being the worst (imho) for this.

Flory says allow 24 hours for Acrylic, & a week(!) for Enamels.

Have you considered Flory Models Clay based washes, these are totaly inert and don't react to anything.

Here he applies over a unspecified satin finish, but I'm having the least issues (I can't gloss for toffee) with Windsor & Newton Galleria Gloss & Satin acrylic varnish.

Flory Models Tutorial: http://promodeller.com/weathering-wash/

US Stockist: https://www.highaltitudehobbies.com/flory-models-products

 

 

 

 

 

I've watched a few Flory Models videos on YouTube but I haven't checked out their weathering wash. Thanks for the suggestion.

Jakealoo

After taking all the advice on board I decided to do a small test on the topside of the Spitfire which I had covered in one light coat of X-22 clear gloss about two weeks ago. The pin wash flowed much better than on the underside (topped with two coats of Klear) although I'm finding that some of the panel lines in this 1/72 kit are so shallow there is very little to flow into.

After letting the pin wash dry for 5 to 10 minutes I was able to remove the excess using mineral spirits without affecting the underlying layers. The only sections that didn't work out as well were those shallow panel lines where removing the excess in some cases removed the panel line as well. Overall I'm pleased with the result and have learned a lot in the process.

 

Yep. Now experiment with length of time the pin wash dries for and the level your wiping cloth/cotton bud/qtip is saturated with the mineral spirits. You can probably let the spirits half dry out before you wipe. Something to play around with at least.

After taking all the advice on board I decided to do a small test on the topside of the Spitfire which I had covered in one light coat of X-22 clear gloss about two weeks ago. The pin wash flowed much better than on the underside (topped with two coats of Klear) although I'm finding that some of the panel lines in this 1/72 kit are so shallow there is very little to flow into.

After letting the pin wash dry for 5 to 10 minutes I was able to remove the excess using mineral spirits without affecting the underlying layers. The only sections that didn't work out as well were those shallow panel lines where removing the excess in some cases removed the panel line as well. Overall I'm pleased with the result and have learned a lot in the process.

For a pin wash I always try very hard to keep the wash tight into the line I am applying it to, to minimize any cleanup. I find it is very hard to apply a solvent wash and clean up afterwards without affecting the sheen, even if the color does not come off.

Jakealoo

Thanks Stikpusher and Phil_H ... I will increase the drying times as you suggest. Some of the paint manufacturers imply that the first coat can be applied just minutes after using their primer but perhaps that's just a means of increasing sales. I recently picked up a bottle of Stynylrez "Easy App Surface Primer" and it says "Let dry 5 to 8 minutes (3 minutes if dried with an artifical heat source)". Nevertheless I will follow your advice.

 

Those are mighty fast times on that Stynylrez, not to mention weather conditions, humidity factors etc.. I cook it for 30-40 minutes in the dehydrator this time of year, maybe 20 minutes in dry winter weather or let it go a few hours if air drying. And overnight air drying in humid weather. After you work with it for a while you get a feel for it.

Edit: I just shot some Stynylrez this afternoon, thinned a little with 91% ipa. You don't get any more humid day than today around these parts, the primer was still wet after about 8 minutes air drying or so and it's now about finishing up in the dehydrator. There is no way you were putting anything over that primer today without the heat setting. I think it will be dry when it comes out of the dehydrator by looking in there though.  30 minutes @ 105 f and about 8 minutes dry time before it went in.

I can't comment about curing times, as I build so slow my club nickname is glacier!

I have noted in my own use of a dozen types of paint, some are considerably more sensitive to handling.

In my use (your milage may vary) Hataka def. needs a good primer (badger Stynylres or Halfords rattle-can),  with Tamiya & MIG being the most durable to handling.

All paints need time to cure fully, so if, as above, the coats closest to the plastic aren't cured, they can delaminate, with Valejo Polyurethane primers being the worst (imho) for this.

Flory says allow 24 hours for Acrylic, & a week(!) for Enamels.

Have you considered Flory Models Clay based washes, these are totaly inert and don't react to anything.

Here he applies over a unspecified satin finish, but I'm having the least issues (I can't gloss for toffee) with Windsor & Newton Galleria Gloss & Satin acrylic varnish.

Flory Models Tutorial: http://promodeller.com/weathering-wash/

US Stockist: https://www.highaltitudehobbies.com/flory-models-products

As an autobody/paint tech I agree.  While you can top coat fairly quickly, paint will take at least a day or so to fully cure even though it is dry to the touch.  Enamels even more so than laquers or acrylics.

I'd give acrylics at least a full day and laquers 2 days

Jakealoo

Some of the paint manufacturers imply that the first coat can be applied just minutes after using their primer

In your case, Tamiya's Surface Primer, whether it be in the spray can or a 40ml jar, is a lacquer based product. At 30 minutes, I'd rather suspect it's still outgassing, which may be detrimental to an acrylic color/top coat.

Thanks Stikpusher and Phil_H ... I will increase the drying times as you suggest. Some of the paint manufacturers imply that the first coat can be applied just minutes after using their primer but perhaps that's just a means of increasing sales. I recently picked up a bottle of Stynylrez "Easy App Surface Primer" and it says "Let dry 5 to 8 minutes (3 minutes if dried with an artifical heat source)". Nevertheless I will follow your advice.

modelmaker66

I have found x-22 is not a good clear coat if you use enamel washes.

I was wondering. Thank you for posting that.

Jakealoo

I left the Tamiya Fine Scale Primer to dry for 30 minutes before applying a layer of Tamiya acrylic. I left that for several hours before applying two coats of Klear which I'm leaving to cure for at least 24 hours.

I'd have left the primer for 12 hours before applying the colour coat, then another 12 hours before applying the clear coat, which then should be left for 12-18 hours.

As Stik said, Tamiya acrylics are touch-dry in minutes when airbrushed, but are still soft for some hours before they're fully cured.

Applying the clear coat over it all further increases the curing time as it adds a more or less impermeable layer which blocks exposure to oxygen, which is required for the curing process.

Jakealoo

Thanks ... my replies to everyone's responses are being moderated and so the answer to the first question (which was asked earlier today) hasn't appeared yet. I'm in the process of doing another test where I left the Tamiya Fine Scale Primer to dry for 30 minutes before applying a layer of Tamiya acrylic. I left that for several hours before applying two coats of Klear which I'm leaving to cure for at least 24 hours. I've been using a cotton bud lightly soaked in thinner. I may have pressed too hard the first time I attempted to remove the excess pin wash (from the 1/72 Spitfire) but on my second test I was very careful not to apply too much pressure but obviously not careful enough (unless the Testors is to blame). On the current test I will use mineral spirits and go easy on the cotton bud. Thanks again.

 

I like to let any primer coat dry and cure overnite before any next colors are applied on top of the primer. If you’re only waiting at most a couple of hours, that does not give anything time to cure, only time to be surface dry. 

I think I'm going to try one coat of Klear rather than two and see what happens.

Testing can be fun ... this afternoon I experimented with what happens when you forget to replace the nozzle after cleaning an airbrush.  Luckily I use a spray booth and so the collatoral damage was minimal. Lesson learned!

I have found x-22 is not a good clear coat if you use enamel washes. It will do just what happened to you.. I suggest mr. hobby GX100 Super Clear III, Alclad clear coat or johnson's klear.

 I think it's safe to say go back to X 22 now that you see mineral spirits works and doesn't hurt acrylic clears. You can always test it on a sprue if you're unsure. I already know it's safe but you may need to prove that to yourself. To me testing is more fun than building lol !

Happy to hear you are making progress.

Thanks Greg. Originally I used Tamiya X-22 on the Spitfire but after encountering the problem I decided to try Klear as so many others rave about it (I'm actually using "Revive" which is newer version of it).

The good news is that the mineral spirits worked much better. I let the two coats of Klear (Revive) dry for over 24 hours and none of the underlying paint layers were affected when I removed the excess Tamiya Panel Line Accent. The only negative was that the capillary action on the panel lines was not as good as it was when using the X-22. I suspect my two coats may have been a little heavy for the tiny panel lines on a 1/72 aircraft. This made the clean up a bit tricky and the results aren't quite as good as I had hoped but good enough. When I do the topside of the aircraft I'm only going to use a single coat of Klear and let it dry over the weekend.

Thanks to everyone for their help.

That seems like a lot of paint coats in a short time to me, but then I am a very slow builder so my opinion might be skewed. If your paint coats are thin, maybe you are ok but it you are heavy-handed with the airbrush like me, I think you might want to consider longer dry times.

In your OP you mentioned using Tamiya clear coat, in your last post you typed "Klear". I'm a little confused.

The is the second post here in 2 days regarding a solvent-based thinner damaging an underlying Tamiya acrylic coat. I don't use a lot of Tamiya, and I hope somebody with Tamiya experience will chime in. I regularly use home made enamal wash made with Testors enamels and Testors enamel thinner over acrylic clear coats without problems, but I've never done it over the top of any Tamiya acrylic product.