Model horses can get stained in a variety of ways: Most commonly, tack is left on long enough for the leather or thread dyes to leach out and stain the model. Blankets are a big culprit. Leaning them against colored curtains or fabric can do it, and wrapping models for storage in colored fabrics can cause stains as well. Other stains may be caused by mold when models are exposed to damp or humid conditions, particularly while in storage for long periods.
The best cure, of course, is prevention. If you love that beautiful new tack set, take photos of the model wearing it and post them near him on the shelf... then untack him. A little saddle rack can allow you to display the tack safely as well.
Some people like to keep blankets on their models to protect them from rubbing against other models... That's great, but use only white or undyed fabrics and stitching. All colors are susceptible to causing stains. Alternately, if protection is more important than shelf fashion, you could drape a bit of plastic wrap or even soft toilet paper over their hindquarters, as those are generally the widest part of the model and most likely to bump against its neighbor. Even safer is to use no blankets at all, instead using a bit of Museum Putty under their feet to keep them steady and upright.
When storing your models, which we hope you don't have to do for long periods - After all we love models because they're fun to look at! - We recommend wrapping them in soft white fabric like undyed t-shirts, soft sheets, white towels, etc. Preferably, air flow should be allowed to circulate around the models, as in airtight containers, certain models (specifically those made in the early 1990s) can see an increase in vinegar syndrome, becoming shrinkies. ALWAYS store them in dry places. If storing them in a basement, we strongly recommend putting pallets under the boxes or placing them on shelves well above the floor in case of unexpected flooding from rain or pipe damage. Models stored here are kept in cardboard boxes (better air flow than plastic totes) on shelving, in a climate-controlled area. If you do have to store them for several months or longer, I strongly recommend buying a bag of silica packets (here's a link to a 50-pack of 5gram packets on eBay) and throwing a couple packets into each storage box to help absorb any dampness they happen to get exposed to. They're cheap insurance against mold, which can ruin models permanently.
Too late! My model is stained. What can I do?
The technique we discuss below has worked well for us on both white and colored model horses. As always, we must add the disclaimer: Try this technique at your own risk. Every model is different. If you're uncertain, be sure to test the model first. We'll tell you how in a moment.
Here we have two models with stains. They have had some time in the sun to brighten up as much as they can on their own, as they were also very yellow when we got them. The sun corrected the yellowing, but didn't touch the stains, which were from blue blankets they wore for years. (These guys are still wearing their masking tape, which protected pink areas from the sun while they sunbathed. It doesn't need to be on for bleaching, but since we were going to put them outside for the process, I left it on for continued protection against fading.)
Safety first - Bleach can be dangerous! This should only be performed by an adult, with care and plenty of ventilation.
a bottle of plain bleach
a paper towel
an old (non-metallic) bowl, an old towel
and an easy way to transport your models outside if you're doing more than one.
We used a plastic tote lid as a carrying tray so we could take the models outdoors once the bleach is applied. Over that we placed an old towel for padding. Yes, it's colored, but they won't be lying against it for more than a couple of days, during which time the towel will remain dry and they'll have plenty of airflow around them.
Pour a small amount (a few tablespoons should do) of bleach into the bowl. If using on unpainted white areas of a model, you can use it full strength. If using on a colored model, I'd mix it half and half with water.
We have used this technique with factory painted, matte finish models as well, include a bay and a dapple grey. In our experience, the bleach did not harm either the paint or the finish over a short period, but did begin to fade the color after 24 hours. Even so, we'd strongly recommend using a tiny bit of bleached paper towel between the hind legs as a test, checking occasionally and leaving it on for at least 24 hours if no issues are seen.
We DO NOT recommend using bleach for Woodgrain models or those with metallic paint or glittery effects in their paint. We've used bleach on glossies twice - It worked beautifully on a Breyerfest Athos with blanket stains, but didn't have any effect on a vintage glossy leopard App Western Prancer. It didn't appear to harm the finish on either model, but again: Always test to be sure before using it on valuable models! Every model and situation is different, so it pays to be careful.
If all is good, you're ready to treat them: We tear a small section from the paper towel, just large enough to cover the stain. You don't have to be exact... We just tear off a bit around the right size. We dip this into the bleach, holding it by a corner that stays out of the bleach... the fluid will make its way up to that corner on its own. Then we gently apply the bit of soaked paper towel onto the stained area of the model, pressing it down gently so that it contacts the surface fully, but not so hard that we squeeze out the bleach. Repeat for each stain.
Mold spots may require larger areas to be covered, as on the mare's back in the photo above. The same principle applies, and we generally prefer to "papier mache" them with small sections of paper towel than try to handle larger ones, which can drip and splash.
Once the areas are covered, take the model(s) out of your living space, because bleach gives off awful fumes, and trust me, once it gets into your nose, you'll smell it for weeks! We let ours rest out on our covered porch, where there's plenty of air flow, no danger of bad weather harming them, etc. The towel will keep them safe from tumbling over and getting damaged.
I usually let them sit around 12 hours, and then visit them with a refresher of bleach, which will have evaporated by then. To re-apply the bleach, the best tool is an eyedropper. If none is available, a drinking straw will work nicely. Dip the straw into the bleach bottle and stopper the top end with your finger. Hold the bottom of the straw against the paper towel bit and gently drip bleach on until it's soaked again.
Let them sit another 12 hours or so, and then carefully remove the paper towel to check their progress. Often that's all the time it needs, but we've come across stubborn stains that have taken 2-3 days.
Here's our mare after 36 hours of bleach treatment. I haven't rinsed her yet, just wiped off the paper towel, which had pretty much disintegrated by then.
After removing the paper towel bits, give your horse a good rinse in room temp water and carefully pat dry with a soft towel. This mare came to us with mold spots over her entire back and one side of her neck, and they were completely removed by the bleach.
The stallion in our photo needed more time, but also showed very good results when finished.
I hope this helps bring new hope to stained models, and serves to warn those of you who like to keep blankets, tack, or rosette drapes on your models. The first model I accidentally stained was wearing a show harness, and it was the thread the harness was sewn with that left stains. Protect your ponies... Let them be naked!